feat: nix_nar

feat: initial nix-daemon implementation
feat: string context
2026-01-18 01:04:44 +08:00 · 2026-01-18 01:04:25 +08:00 · 2026-01-18 00:52:31 +08:00 · 2026-01-18 00:52:11 +08:00 · 2026-01-17 16:42:10 +08:00
46 changed files with 2747 additions and 1181 deletions
--- a/.lazy.lua
+++ b/.lazy.lua
@@ -1,7 +1,18 @@
 vim.lsp.config("biome", {
-  root_dir = function (bufnr, on_dir)
+  root_dir = function (_bufnr, on_dir)
    on_dir(vim.fn.getcwd())
  end
 })
+vim.lsp.config("rust_analyzer", {
+  settings = {
+    ["rust-analyzer"] = {
+      cargo = {
+        features = {
+          "daemon"
+        }
+      }
+    }
+  }
+})

 return {}
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -34,6 +34,15 @@ version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"

+[[package]]
+name = "android_system_properties"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "819e7219dbd41043ac279b19830f2efc897156490d7fd6ea916720117ee66311"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "anes"
 version = "0.1.6"
@@ -61,6 +70,28 @@ dependencies = [
 "derive_arbitrary",
 ]

+[[package]]
+name = "async-stream"
+version = "0.3.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b5a71a6f37880a80d1d7f19efd781e4b5de42c88f0722cc13bcb6cc2cfe8476"
+dependencies = [
+ "async-stream-impl",
+ "futures-core",
+ "pin-project-lite",
+]
+
+[[package]]
+name = "async-stream-impl"
+version = "0.3.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c7c24de15d275a1ecfd47a380fb4d5ec9bfe0933f309ed5e705b775596a3574d"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "atomic-waker"
 version = "1.1.2"
@@ -95,6 +126,12 @@ dependencies = [
 "vsimd",
 ]

+[[package]]
+name = "base64ct"
+version = "1.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2af50177e190e07a26ab74f8b1efbfe2ef87da2116221318cb1c2e82baf7de06"
+
 [[package]]
 name = "bincode"
 version = "1.3.3"
@@ -176,6 +213,17 @@ dependencies = [
 "syn",
 ]

+[[package]]
+name = "bstr"
+version = "1.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "63044e1ae8e69f3b5a92c736ca6269b8d12fa7efe39bf34ddb06d102cf0e2cab"
+dependencies = [
+ "memchr",
+ "regex-automata",
+ "serde",
+]
+
 [[package]]
 name = "bumpalo"
 version = "3.19.0"
@@ -223,6 +271,12 @@ dependencies = [
 "displaydoc",
 ]

+[[package]]
+name = "camino"
+version = "1.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e629a66d692cb9ff1a1c664e41771b3dcaf961985a9774c0eb0bd1b51cf60a48"
+
 [[package]]
 name = "capacity_builder"
 version = "0.5.0"
@@ -266,7 +320,7 @@ version = "0.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6fac387a98bb7c37292057cffc56d62ecb629900026402633ae9160df93a8766"
 dependencies = [
- "nom",
+ "nom 7.1.3",
 ]

 [[package]]
@@ -287,6 +341,19 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"

+[[package]]
+name = "chrono"
+version = "0.4.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fac4744fb15ae8337dc853fee7fb3f4e48c0fbaa23d0afe49c447b4fab126118"
+dependencies = [
+ "iana-time-zone",
+ "js-sys",
+ "num-traits",
+ "wasm-bindgen",
+ "windows-link",
+]
+
 [[package]]
 name = "ciborium"
 version = "0.2.2"
@@ -369,6 +436,12 @@ dependencies = [
 "error-code",
 ]

+[[package]]
+name = "const-oid"
+version = "0.9.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c2459377285ad874054d797f3ccebf984978aa39129f6eafde5cdc8315b612f8"
+
 [[package]]
 name = "constant_time_eq"
 version = "0.3.1"
@@ -399,6 +472,12 @@ version = "5.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "147be55d677052dabc6b22252d5dd0fd4c29c8c27aa4f2fbef0f94aa003b406f"

+[[package]]
+name = "core-foundation-sys"
+version = "0.8.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "773648b94d0e5d620f64f280777445740e61fe701025087ec8b57f45c791888b"
+
 [[package]]
 name = "core_maths"
 version = "0.1.1"
@@ -524,6 +603,33 @@ dependencies = [
 "typenum",
 ]

+[[package]]
+name = "curve25519-dalek"
+version = "4.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97fb8b7c4503de7d6ae7b42ab72a5a59857b4c937ec27a3d4539dba95b5ab2be"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "curve25519-dalek-derive",
+ "digest",
+ "fiat-crypto",
+ "rustc_version",
+ "subtle",
+ "zeroize",
+]
+
+[[package]]
+name = "curve25519-dalek-derive"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f46882e17999c6cc590af592290432be3bce0428cb0d5f8b6715e4dc7b383eb3"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "data-encoding"
 version = "2.9.0"
@@ -657,6 +763,16 @@ dependencies = [
 "tokio",
 ]

+[[package]]
+name = "der"
+version = "0.7.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7c1832837b905bbfb5101e07cc24c8deddf52f93225eee6ead5f4d63d53ddcb"
+dependencies = [
+ "const-oid",
+ "zeroize",
+]
+
 [[package]]
 name = "deranged"
 version = "0.5.5"
@@ -775,6 +891,30 @@ dependencies = [
 "syn",
 ]

+[[package]]
+name = "ed25519"
+version = "2.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "115531babc129696a58c64a4fef0a8bf9e9698629fb97e9e40767d235cfbcd53"
+dependencies = [
+ "pkcs8",
+ "signature",
+]
+
+[[package]]
+name = "ed25519-dalek"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "70e796c081cee67dc755e1a36a0a172b897fab85fc3f6bc48307991f64e4eca9"
+dependencies = [
+ "curve25519-dalek",
+ "ed25519",
+ "serde",
+ "sha2",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "either"
 version = "1.15.0"
@@ -826,6 +966,12 @@ dependencies = [
 "windows-sys 0.59.0",
 ]

+[[package]]
+name = "fiat-crypto"
+version = "0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "28dea519a9695b9977216879a3ebfddf92f1c08c05d984f8996aecd6ecdc811d"
+
 [[package]]
 name = "filetime"
 version = "0.2.26"
@@ -1206,6 +1352,30 @@ dependencies = [
 "tracing",
 ]

+[[package]]
+name = "iana-time-zone"
+version = "0.1.64"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "33e57f83510bb73707521ebaffa789ec8caf86f9657cad665b092b581d40e9fb"
+dependencies = [
+ "android_system_properties",
+ "core-foundation-sys",
+ "iana-time-zone-haiku",
+ "js-sys",
+ "log",
+ "wasm-bindgen",
+ "windows-core",
+]
+
+[[package]]
+name = "iana-time-zone-haiku"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f31827a206f56af32e590ba56d5d2d085f558508192593743f16b2306495269f"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "icu_calendar"
 version = "2.1.1"
@@ -1406,6 +1576,15 @@ dependencies = [
 "windows-sys 0.61.2",
 ]

+[[package]]
+name = "is_executable"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baabb8b4867b26294d818bf3f651a454b6901431711abb96e296245888d6e8c4"
+dependencies = [
+ "windows-sys 0.60.2",
+]
+
 [[package]]
 name = "itertools"
 version = "0.10.5"
@@ -1465,6 +1644,12 @@ dependencies = [
 "wasm-bindgen",
 ]

+[[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+
 [[package]]
 name = "libc"
 version = "0.2.179"
@@ -1568,6 +1753,15 @@ dependencies = [
 "pkg-config",
 ]

+[[package]]
+name = "matchers"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d1525a2a28c7f4fa0fc98bb91ae755d1e2d1505079e05539e35bc876b5d65ae9"
+dependencies = [
+ "regex-automata",
+]
+
 [[package]]
 name = "memchr"
 version = "2.7.5"
@@ -1640,6 +1834,57 @@ dependencies = [
 "libc",
 ]

+[[package]]
+name = "nix-compat"
+version = "0.1.0"
+source = "git+https://git.snix.dev/snix/snix.git#5b3716a16b64771013c1c6aefaf3c9fd218e4db8"
+dependencies = [
+ "bitflags",
+ "bstr",
+ "bytes",
+ "data-encoding",
+ "ed25519",
+ "ed25519-dalek",
+ "futures",
+ "mimalloc",
+ "nix-compat-derive",
+ "nom 8.0.0",
+ "num_enum",
+ "pin-project-lite",
+ "sha2",
+ "thiserror 2.0.17",
+ "tokio",
+ "tracing",
+]
+
+[[package]]
+name = "nix-compat-derive"
+version = "0.1.0"
+source = "git+https://git.snix.dev/snix/snix.git#5b3716a16b64771013c1c6aefaf3c9fd218e4db8"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "nix-daemon"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bb28bc02b8ea18d59e15fc8e86ae35850326dc5e4e2dcf17bc659f2fd79f1a08"
+dependencies = [
+ "async-stream",
+ "chrono",
+ "futures",
+ "num_enum",
+ "tap",
+ "thiserror 1.0.69",
+ "tokio",
+ "tokio-stream",
+ "tokio-test",
+ "tracing",
+]
+
 [[package]]
 name = "nix-js"
 version = "0.1.0"
@@ -1656,7 +1901,10 @@ dependencies = [
 "hex",
 "itertools 0.14.0",
 "mimalloc",
+ "nix-compat",
+ "nix-daemon",
 "nix-js-macros",
+ "nix-nar",
 "petgraph",
 "regex",
 "reqwest",
@@ -1669,6 +1917,9 @@ dependencies = [
 "tar",
 "tempfile",
 "thiserror 2.0.17",
+ "tokio",
+ "tracing",
+ "tracing-subscriber",
 "xz2",
 "zip",
 ]
@@ -1683,6 +1934,18 @@ dependencies = [
 "syn",
 ]

+[[package]]
+name = "nix-nar"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "15dbfa157df89f4283825ff1c21d53344cfe0d222ea8fde0f9514206dc62d9e0"
+dependencies = [
+ "camino",
+ "is_executable",
+ "symlink",
+ "thiserror 1.0.69",
+]
+
 [[package]]
 name = "nom"
 version = "7.1.3"
@@ -1693,6 +1956,24 @@ dependencies = [
 "minimal-lexical",
 ]

+[[package]]
+name = "nom"
+version = "8.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df9761775871bdef83bee530e60050f7e54b1105350d6884eb0fb4f46c2f9405"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "nu-ansi-term"
+version = "0.50.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7957b9740744892f114936ab4a57b3f487491bbeafaf8083688b16841a4240e5"
+dependencies = [
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "num-bigint"
 version = "0.4.6"
@@ -1728,6 +2009,28 @@ dependencies = [
 "autocfg",
 ]

+[[package]]
+name = "num_enum"
+version = "0.7.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b1207a7e20ad57b847bbddc6776b968420d38292bbfe2089accff5e19e82454c"
+dependencies = [
+ "num_enum_derive",
+ "rustversion",
+]
+
+[[package]]
+name = "num_enum_derive"
+version = "0.7.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ff32365de1b6743cb203b710788263c44a03de03802daf96092f2da4fe6ba4d7"
+dependencies = [
+ "proc-macro-crate",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "once_cell"
 version = "1.21.3"
@@ -1841,6 +2144,16 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"

+[[package]]
+name = "pkcs8"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f950b2377845cebe5cf8b5165cb3cc1a5e0fa5cfa3e1f7f55707d8fd82e0a7b7"
+dependencies = [
+ "der",
+ "spki",
+]
+
 [[package]]
 name = "pkg-config"
 version = "0.3.32"
@@ -1911,6 +2224,15 @@ dependencies = [
 "syn",
 ]

+[[package]]
+name = "proc-macro-crate"
+version = "3.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "219cb19e96be00ab2e37d6e299658a0cfa83e52429179969b0f0121b4ac46983"
+dependencies = [
+ "toml_edit",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.95"
@@ -2040,6 +2362,9 @@ name = "rand_core"
 version = "0.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom 0.2.16",
+]

 [[package]]
 name = "rand_core"
@@ -2443,6 +2768,15 @@ dependencies = [
 "digest",
 ]

+[[package]]
+name = "sharded-slab"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f40ca3c46823713e0d4209592e8d6e826aa57e928f09752619fc696c499637f6"
+dependencies = [
+ "lazy_static",
+]
+
 [[package]]
 name = "shlex"
 version = "1.3.0"
@@ -2459,6 +2793,15 @@ dependencies = [
 "libc",
 ]

+[[package]]
+name = "signature"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77549399552de45a898a580c1b41d445bf730df867cc44e6c0233bbc4b8329de"
+dependencies = [
+ "rand_core 0.6.4",
+]
+
 [[package]]
 name = "simd-adler32"
 version = "0.3.8"
@@ -2505,6 +2848,16 @@ dependencies = [
 "url",
 ]

+[[package]]
+name = "spki"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d91ed6c858b01f942cd56b37a94b3e0a1798290327d1236e4d9cf4eaca44d29d"
+dependencies = [
+ "base64ct",
+ "der",
+]
+
 [[package]]
 name = "stable_deref_trait"
 version = "1.2.1"
@@ -2569,6 +2922,12 @@ version = "2.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "13c2bddecc57b384dee18652358fb23172facb8a2c51ccc10d74c157bdea3292"

+[[package]]
+name = "symlink"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7973cce6668464ea31f176d85b13c7ab3bba2cb3b77a2ed26abd7801688010a"
+
 [[package]]
 name = "syn"
 version = "2.0.104"
@@ -2740,6 +3099,15 @@ dependencies = [
 "syn",
 ]

+[[package]]
+name = "thread_local"
+version = "1.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f60246a4944f24f6e018aa17cdeffb7818b76356965d03b07d6a9886e8962185"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "time"
 version = "0.3.44"
@@ -2845,6 +3213,58 @@ dependencies = [
 "tokio",
 ]

+[[package]]
+name = "tokio-stream"
+version = "0.1.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32da49809aab5c3bc678af03902d4ccddea2a87d028d86392a4b1560c6906c70"
+dependencies = [
+ "futures-core",
+ "pin-project-lite",
+ "tokio",
+]
+
+[[package]]
+name = "tokio-test"
+version = "0.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f6d24790a10a7af737693a3e8f1d03faef7e6ca0cc99aae5066f533766de545"
+dependencies = [
+ "futures-core",
+ "tokio",
+ "tokio-stream",
+]
+
+[[package]]
+name = "toml_datetime"
+version = "0.7.5+spec-1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "92e1cfed4a3038bc5a127e35a2d360f145e1f4b971b551a2ba5fd7aedf7e1347"
+dependencies = [
+ "serde_core",
+]
+
+[[package]]
+name = "toml_edit"
+version = "0.23.10+spec-1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "84c8b9f757e028cee9fa244aea147aab2a9ec09d5325a9b01e0a49730c2b5269"
+dependencies = [
+ "indexmap",
+ "toml_datetime",
+ "toml_parser",
+ "winnow",
+]
+
+[[package]]
+name = "toml_parser"
+version = "1.0.6+spec-1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a3198b4b0a8e11f09dd03e133c0280504d0801269e9afa46362ffde1cbeebf44"
+dependencies = [
+ "winnow",
+]
+
 [[package]]
 name = "tower"
 version = "0.5.2"
@@ -2897,9 +3317,21 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "63e71662fa4b2a2c3a26f570f037eb95bb1f85397f3cd8076caed2f026a6d100"
 dependencies = [
 "pin-project-lite",
+ "tracing-attributes",
 "tracing-core",
 ]

+[[package]]
+name = "tracing-attributes"
+version = "0.1.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7490cfa5ec963746568740651ac6781f701c9c5ea257c58e057f3ba8cf69e8da"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "tracing-core"
 version = "0.1.36"
@@ -2907,6 +3339,36 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "db97caf9d906fbde555dd62fa95ddba9eecfd14cb388e4f491a66d74cd5fb79a"
 dependencies = [
 "once_cell",
+ "valuable",
+]
+
+[[package]]
+name = "tracing-log"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee855f1f400bd0e5c02d150ae5de3840039a3f54b025156404e34c23c03f47c3"
+dependencies = [
+ "log",
+ "once_cell",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-subscriber"
+version = "0.3.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2f30143827ddab0d256fd843b7a66d164e9f271cfa0dde49142c5ca0ca291f1e"
+dependencies = [
+ "matchers",
+ "nu-ansi-term",
+ "once_cell",
+ "regex-automata",
+ "sharded-slab",
+ "smallvec",
+ "thread_local",
+ "tracing",
+ "tracing-core",
+ "tracing-log",
 ]

 [[package]]
@@ -3008,6 +3470,12 @@ dependencies = [
 "which",
 ]

+[[package]]
+name = "valuable"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ba73ea9cf16a25df0c8caa16c51acb937d5712a8429db78a3ee29d5dcacd3a65"
+
 [[package]]
 name = "version_check"
 version = "0.9.5"
@@ -3194,12 +3662,65 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"

+[[package]]
+name = "windows-core"
+version = "0.62.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8e83a14d34d0623b51dce9581199302a221863196a1dde71a7663a4c2be9deb"
+dependencies = [
+ "windows-implement",
+ "windows-interface",
+ "windows-link",
+ "windows-result",
+ "windows-strings",
+]
+
+[[package]]
+name = "windows-implement"
+version = "0.60.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "053e2e040ab57b9dc951b72c264860db7eb3b0200ba345b4e4c3b14f67855ddf"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "windows-interface"
+version = "0.59.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f316c4a2570ba26bbec722032c4099d8c8bc095efccdc15688708623367e358"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "windows-link"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5"

+[[package]]
+name = "windows-result"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7781fa89eaf60850ac3d2da7af8e5242a5ea78d1a11c49bf2910bb5a73853eb5"
+dependencies = [
+ "windows-link",
+]
+
+[[package]]
+name = "windows-strings"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7837d08f69c77cf6b07689544538e017c1bfcf57e34b4c0ff58e6c2cd3b37091"
+dependencies = [
+ "windows-link",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.48.0"
@@ -3431,6 +3952,15 @@ version = "0.53.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d6bbff5f0aada427a1e5a6da5f1f98158182f26556f345ac9e04d36d0ebed650"

+[[package]]
+name = "winnow"
+version = "0.7.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a5364e9d77fcdeeaa6062ced926ee3381faa2ee02d3eb83a5c27a8825540829"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "winsafe"
 version = "0.0.19"
--- a/15
+++ b/15
@@ -0,0 +1,15 @@
+[no-exit-message]
+@repl:
+  RUST_LOG=none,nix_js=debug cargo run --bin repl
+
+[no-exit-message]
+@eval expr:
+  RUST_LOG=none,nix_js=debug cargo run --bin eval -- '{{expr}}'
+
+[no-exit-message]
+@replr:
+  cargo run --bin repl --release
+
+[no-exit-message]
+@evalr expr:
+  cargo run --bin eval --release -- '{{expr}}'
--- a/flake.nix
+++ b/flake.nix
@@ -18,7 +18,7 @@
        {
          default = pkgs.mkShell {
            packages = with pkgs; [
-              (fenix.packages.${system}.stable.withComponents [
+              (fenix.packages.${system}.latest.withComponents [
                "cargo"
                "clippy"
                "rust-src"
@@ -30,6 +30,7 @@
              lldb
              valgrind
              hyperfine
+              just

              nodejs
              nodePackages.npm
--- a/nix-js/Cargo.toml
+++ b/nix-js/Cargo.toml
@@ -4,13 +4,24 @@ version = "0.1.0"
 edition = "2024"
 build = "build.rs"

+[features]
+default = ["daemon"]
+daemon = ["dep:tokio", "dep:nix-daemon"]
+
 [dependencies]
 mimalloc = "0.1"

+tokio = { version = "1.41", features = ["rt-multi-thread", "sync"], optional = true }
+nix-daemon = { version = "0.1", optional = true }
+
 # REPL
 anyhow = "1.0"
 rustyline = "14.0"

+# Logging
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+
 derive_more = { version = "2", features = ["full"] }
 thiserror = "2"

@@ -25,6 +36,7 @@ regex = "1.11"
 deno_core = "0.376"
 deno_error = "0.7"

+nix-nar = "0.3"
 sha2 = "0.10"
 hex = "0.4"

--- a/nix-js/build.rs
+++ b/nix-js/build.rs
@@ -1,4 +1,3 @@
-use std::env;
 use std::path::Path;
 use std::process::Command;

@@ -68,9 +67,4 @@ fn main() {
    } else {
        panic!("dist/runtime.js not found after build");
    }
-
-    // Print build info
-    if env::var("CARGO_CFG_DEBUG_ASSERTIONS").is_ok() {
-        println!("Built runtime.js in DEBUG mode");
-    }
 }
--- a/nix-js/runtime-ts/src/builtins/attrs.ts
+++ b/nix-js/runtime-ts/src/builtins/attrs.ts
@@ -4,6 +4,7 @@

 import type { NixValue, NixAttrs, NixList } from "../types";
 import { forceAttrs, forceString, forceFunction, forceList } from "../type-assert";
+import { createThunk } from "../thunk";

 export const attrNames = (set: NixValue): string[] => Object.keys(forceAttrs(set)).sort();

@@ -22,17 +23,13 @@ export const hasAttr =
 export const mapAttrs =
  (f: NixValue) =>
  (attrs: NixValue): NixAttrs => {
-    const forced_attrs = forceAttrs(attrs);
-    const forced_f = forceFunction(f);
-    const new_attrs: NixAttrs = {};
-    for (const key in forced_attrs) {
-      Object.defineProperty(new_attrs, key, {
-        get: () => forceFunction(forced_f(key))(forced_attrs[key]),
-        enumerable: true,
-        configurable: true,
-      });
+    const forcedAttrs = forceAttrs(attrs);
+    const forcedF = forceFunction(f);
+    const newAttrs: NixAttrs = {};
+    for (const key in forcedAttrs) {
+      newAttrs[key] = createThunk(() => forceFunction(forcedF(key))(forcedAttrs[key]));
    }
-    return new_attrs;
+    return newAttrs;
  };

 export const removeAttrs =
--- a/nix-js/runtime-ts/src/builtins/context.ts
+++ b/nix-js/runtime-ts/src/builtins/context.ts
@@ -11,16 +11,33 @@ import {
  parseContextToInfoMap,
 } from "../string-context";

+/**
+ * builtins.hasContext - Check if string has context
+ *
+ * Returns true if the string has any store path references.
+ */
 export const hasContext = (value: NixValue): boolean => {
  const s = forceNixString(value);
  return isStringWithContext(s) && s.context.size > 0;
 };

+/**
+ * builtins.unsafeDiscardStringContext - Remove all context from string
+ *
+ * IMPORTANT: This discards string context, returning only the string value.
+ * Use with caution as it removes derivation dependencies.
+ */
 export const unsafeDiscardStringContext = (value: NixValue): string => {
  const s = forceNixString(value);
  return getStringValue(s);
 };

+/**
+ * builtins.unsafeDiscardOutputDependency - Convert DrvDeep to Opaque context
+ *
+ * IMPORTANT: Transforms "all outputs" references (=) to plain path references.
+ * Preserves other context types unchanged.
+ */
 export const unsafeDiscardOutputDependency = (value: NixValue): NixString => {
  const s = forceNixString(value);
  const strValue = getStringValue(s);
@@ -47,6 +64,12 @@ export const unsafeDiscardOutputDependency = (value: NixValue): NixString => {
  return mkStringWithContext(strValue, newContext);
 };

+/**
+ * builtins.addDrvOutputDependencies - Convert Opaque to DrvDeep context
+ *
+ * IMPORTANT: Transforms plain derivation path references to "all outputs" references (=).
+ * The string must have exactly one context element which must be a .drv path.
+ */
 export const addDrvOutputDependencies = (value: NixValue): NixString => {
  const s = forceNixString(value);
  const strValue = getStringValue(s);
@@ -77,6 +100,14 @@ export const addDrvOutputDependencies = (value: NixValue): NixString => {
  return mkStringWithContext(strValue, newContext);
 };

+/**
+ * builtins.getContext - Extract context as structured attribute set
+ *
+ * Returns an attribute set mapping store paths to their context info:
+ * - path: true if it's a plain store path reference (opaque)
+ * - allOutputs: true if it references all derivation outputs (drvDeep, encoded as =path)
+ * - outputs: list of specific output names (built, encoded as !output!path)
+ */
 export const getContext = (value: NixValue): NixAttrs => {
  const s = forceNixString(value);
  const context = getStringContext(s);
@@ -101,6 +132,18 @@ export const getContext = (value: NixValue): NixAttrs => {
  return result;
 };

+/**
+ * builtins.appendContext - Add context to a string
+ *
+ * IMPORTANT: Merges the provided context attribute set with any existing context
+ * from the input string. Used to manually construct strings with specific
+ * derivation dependencies.
+ *
+ * Context format matches getContext output:
+ * - path: boolean - add as opaque reference
+ * - allOutputs: boolean - add as drvDeep reference (=)
+ * - outputs: [string] - add as built references (!output!)
+ */
 export const appendContext =
  (strValue: NixValue) =>
  (ctxValue: NixValue): NixString => {
--- a/nix-js/runtime-ts/src/builtins/conversion.ts
+++ b/nix-js/runtime-ts/src/builtins/conversion.ts
@@ -110,6 +110,12 @@ export interface CoerceResult {
 * Coerce a Nix value to a string according to the specified mode.
 * This implements the same behavior as Lix's EvalState::coerceToString.
 *
+ * IMPORTANT: String context preservation rules:
+ * - StringWithContext: Context is collected in outContext parameter
+ * - Derivations (with outPath): Built context is added for the drvPath/outputName
+ * - Lists (ToString mode): Context from all elements is merged
+ * - All other coercions: No context added
+ *
 * @param value - The value to coerce
 * @param mode - The coercion mode (controls which types are allowed)
 * @param copyToStore - If true, paths should be copied to the Nix store (not implemented yet)
--- a/nix-js/runtime-ts/src/builtins/io.ts
+++ b/nix-js/runtime-ts/src/builtins/io.ts
@@ -3,22 +3,33 @@
 * Implemented via Rust ops exposed through deno_core
 */

-import { forceAttrs, forceBool, forceString, forceNixPath } from "../type-assert";
+import { forceAttrs, forceBool, forceString } from "../type-assert";
 import type { NixValue, NixAttrs } from "../types";
 import { isNixPath } from "../types";
 import { force } from "../thunk";
 import { coerceToPath, coerceToString, StringCoercionMode } from "./conversion";
 import { getPathValue } from "../path";
-
-// Declare Deno.core.ops global (provided by deno_core runtime)
+import type { NixStringContext, StringWithContext } from "../string-context";
+import { mkStringWithContext } from "../string-context";

 export const importFunc = (path: NixValue): NixValue => {
-  // TODO: context?
-  const pathStr = coerceToString(path, StringCoercionMode.Base);
+  const context: NixStringContext = new Set();
+  const pathStr = coerceToPath(path, context);
+
+  // FIXME: Context collected but not yet propagated to build system
+  // This means derivation dependencies from imported paths are not
+  // currently tracked. This will cause issues when:
+  // 1. Importing from derivation outputs: import "${drv}/file.nix"
+  // 2. Building packages that depend on imported configurations
+  if (context.size > 0) {
+    console.warn(
+      `[WARN] import: Path has string context which is not yet fully tracked.
+Dependency tracking for imported derivations may be incomplete.`,
+    );
+  }

  // Call Rust op - returns JS code string
  const code = Deno.core.ops.op_import(pathStr);
-
  return Function(`return (${code})`)();
 };

@@ -28,8 +39,14 @@ export const scopedImport =
    throw new Error("Not implemented: scopedImport");
  };

-export const storePath = (args: NixValue): never => {
-  throw new Error("Not implemented: storePath");
+export const storePath = (pathArg: NixValue): StringWithContext => {
+  const context: NixStringContext = new Set();
+  const pathStr = coerceToPath(pathArg, context);
+
+  const validatedPath: string = Deno.core.ops.op_store_path(pathStr);
+
+  context.add(validatedPath);
+  return mkStringWithContext(validatedPath, context);
 };

 export const fetchClosure = (args: NixValue): never => {
@@ -336,9 +353,32 @@ export const path = (args: NixValue): string => {
  return storePath;
 };

-export const toFile = (name: NixValue, s: NixValue): never => {
-  throw new Error("Not implemented: toFile");
-};
+export const toFile =
+  (nameArg: NixValue) =>
+  (contentsArg: NixValue): StringWithContext => {
+    const name = forceString(nameArg);
+
+    if (name.includes('/')) {
+      throw new Error("builtins.toFile: name cannot contain '/'");
+    }
+    if (name === '.' || name === '..') {
+      throw new Error("builtins.toFile: invalid name");
+    }
+
+    const context: NixStringContext = new Set();
+    const contents = coerceToString(
+      contentsArg,
+      StringCoercionMode.ToString,
+      false,
+      context
+    );
+
+    const references: string[] = Array.from(context);
+
+    const storePath: string = Deno.core.ops.op_to_file(name, contents, references);
+
+    return mkStringWithContext(storePath, new Set([storePath]));
+  };

 export const toPath = (name: NixValue, s: NixValue): never => {
  throw new Error("Not implemented: toPath");
--- a/nix-js/runtime-ts/src/builtins/string.ts
+++ b/nix-js/runtime-ts/src/builtins/string.ts
@@ -2,29 +2,83 @@
 * String operation builtin functions
 */

-import type { NixInt, NixValue } from "../types";
-import { forceString, forceList, forceInt } from "../type-assert";
+import type { NixInt, NixValue, NixString } from "../types";
+import { forceString, forceList, forceInt, forceNixString } from "../type-assert";
 import { coerceToString, StringCoercionMode } from "./conversion";
+import {
+  type NixStringContext,
+  getStringValue,
+  getStringContext,
+  mkStringWithContext,
+} from "../string-context";

 export const stringLength = (e: NixValue): NixInt => BigInt(forceString(e).length);

+/**
+ * builtins.substring - Extract substring while preserving string context
+ *
+ * IMPORTANT: String context must be preserved from the source string.
+ * This matches Lix behavior where substring operations maintain references
+ * to store paths and derivations.
+ *
+ * Special case: substring 0 0 str can be used idiomatically to capture
+ * string context efficiently without copying the string value.
+ */
 export const substring =
  (start: NixValue) =>
  (len: NixValue) =>
-  (s: NixValue): string => {
-    const str = forceString(s);
+  (s: NixValue): NixString => {
    const startPos = Number(forceInt(start));
    const length = Number(forceInt(len));
-    return str.substring(startPos, startPos + length);
+
+    if (startPos < 0) {
+      throw new Error("negative start position in 'substring'");
+    }
+
+    const str = forceNixString(s);
+    const strValue = getStringValue(str);
+    const context = getStringContext(str);
+
+    if (length === 0) {
+      if (context.size === 0) {
+        return "";
+      }
+      return mkStringWithContext("", context);
+    }
+
+    const actualLength = length < 0 ? Number.MAX_SAFE_INTEGER : length;
+    const result = startPos >= strValue.length ? "" : strValue.substring(startPos, startPos + actualLength);
+
+    if (context.size === 0) {
+      return result;
+    }
+    return mkStringWithContext(result, context);
  };

+/**
+ * builtins.concatStringsSep - Concatenate strings with separator, merging contexts
+ *
+ * IMPORTANT: String context must be collected from both the separator and all
+ * list elements, then merged into the result. This ensures that store path
+ * references are preserved when building paths like "/nix/store/xxx/bin:/nix/store/yyy/bin".
+ */
 export const concatStringsSep =
  (sep: NixValue) =>
-  (list: NixValue): string =>
-    // FIXME: context?
-    forceList(list)
-      .map((elem) => coerceToString(elem, StringCoercionMode.Interpolation))
-      .join(forceString(sep));
+  (list: NixValue): NixString => {
+    const context: NixStringContext = new Set();
+    const separator = coerceToString(sep, StringCoercionMode.Interpolation, false, context);
+
+    const parts = forceList(list).map((elem) =>
+      coerceToString(elem, StringCoercionMode.Interpolation, false, context),
+    );
+
+    const result = parts.join(separator);
+
+    if (context.size === 0) {
+      return result;
+    }
+    return mkStringWithContext(result, context);
+  };

 export const baseNameOf = (x: NixValue): string => {
  const str = forceString(x);
--- a/nix-js/runtime-ts/src/helpers.ts
+++ b/nix-js/runtime-ts/src/helpers.ts
@@ -3,22 +3,23 @@
 */

 import type { NixValue, NixAttrs, NixBool, NixString, NixPath } from "./types";
-import { forceAttrs, forceFunction, forceString, typeName } from "./type-assert";
+import { forceAttrs, forceBool, forceFunction, forceString, typeName } from "./type-assert";
 import { isAttrs } from "./builtins/type-check";
 import { coerceToString, StringCoercionMode } from "./builtins/conversion";
-import {
-  type NixStringContext,
-  mkStringWithContext,
-  isStringWithContext,
-  getStringContext,
-} from "./string-context";
+import { type NixStringContext, mkStringWithContext, isStringWithContext } from "./string-context";
 import { force } from "./thunk";
 import { mkPath } from "./path";
-import { isNixPath } from "./types";
+import { CatchableError, isNixPath } from "./types";

 /**
 * Concatenate multiple values into a string or path with context
 * This is used for string interpolation like "hello ${world}"
+ *
+ * IMPORTANT: String context handling:
+ * - All contexts from interpolated values are merged into the result
+ * - Path mode: Store contexts are forbidden (will throw error)
+ * - String mode: All contexts are preserved and merged
+ *
 * If first element is a path, result is a path (with constraint: no store context allowed)
 *
 * @param parts - Array of values to concatenate
@@ -98,9 +99,9 @@ export const concatStringsWithContext = (parts: NixValue[]): NixString | NixPath
 * @param path - Path string (may be relative or absolute)
 * @returns NixPath object with absolute path
 */
-export const resolvePath = (path: NixValue): NixPath => {
-  const path_str = forceString(path);
-  const resolved = Deno.core.ops.op_resolve_path(path_str);
+export const resolvePath = (currentDir: string, path: NixValue): NixPath => {
+  const pathStr = forceString(path);
+  const resolved = Deno.core.ops.op_resolve_path(currentDir, pathStr);
  return mkPath(resolved);
 };

@@ -226,3 +227,10 @@ export const call = (func: NixValue, arg: NixValue): NixValue => {
  }
  throw new Error(`attempt to call something which is not a function but ${typeName(forcedFunc)}`);
 };
+
+export const assert = (assertion: NixValue, expr: NixValue, assertionRaw: string): NixValue => {
+  if (forceBool(assertion)) {
+    return expr;
+  }
+  throw new CatchableError(`assertion '${assertionRaw}' failed`);
+};
--- a/nix-js/runtime-ts/src/index.ts
+++ b/nix-js/runtime-ts/src/index.ts
@@ -13,6 +13,7 @@ import {
  hasAttr,
  concatStringsWithContext,
  call,
+  assert,
 } from "./helpers";
 import { op } from "./operators";
 import { builtins, PRIMOP_METADATA } from "./builtins";
@@ -34,6 +35,7 @@ export const Nix = {
  IS_PATH,
  DEBUG_THUNKS,

+  assert,
  call,
  hasAttr,
  select,
--- a/nix-js/runtime-ts/src/operators.ts
+++ b/nix-js/runtime-ts/src/operators.ts
@@ -250,27 +250,5 @@ export const op = {
    return Array.prototype.concat.call(forceList(a), forceList(b));
  },

-  update: (a: NixValue, b: NixValue): NixAttrs => {
-    const forcedA = forceAttrs(a);
-    const forcedB = forceAttrs(b);
-    const newAttrs: NixAttrs = {};
-
-    for (const key in forcedA) {
-      Object.defineProperty(newAttrs, key, {
-        get: () => force(forcedA[key]),
-        enumerable: true,
-        configurable: true,
-      });
-    }
-
-    for (const key in forcedB) {
-      Object.defineProperty(newAttrs, key, {
-        get: () => force(forcedB[key]),
-        enumerable: true,
-        configurable: true,
-      });
-    }
-
-    return newAttrs;
-  },
+  update: (a: NixValue, b: NixValue): NixAttrs => ({ ...forceAttrs(a), ...forceAttrs(b) }),
 };
--- a/nix-js/runtime-ts/src/string-context.ts
+++ b/nix-js/runtime-ts/src/string-context.ts
@@ -1,3 +1,28 @@
+/**
+ * String Context System for Nix
+ *
+ * String context tracks references to store paths and derivations within strings.
+ * This is critical for Nix's dependency tracking - when a string containing a
+ * store path is used in a derivation, that store path becomes a build dependency.
+ *
+ * Context Elements (encoded as strings):
+ * - Opaque: Plain store path reference
+ *   Format: "/nix/store/..."
+ *   Example: "/nix/store/abc123-hello"
+ *
+ * - DrvDeep: Derivation with all outputs
+ *   Format: "=/nix/store/...drv"
+ *   Example: "=/nix/store/xyz789-hello.drv"
+ *   Meaning: All outputs of this derivation and its closure
+ *
+ * - Built: Specific derivation output
+ *   Format: "!<output>!/nix/store/...drv"
+ *   Example: "!out!/nix/store/xyz789-hello.drv"
+ *   Meaning: Specific output (e.g., "out", "dev", "lib") of this derivation
+ *
+ * This implementation matches Lix's NixStringContext system.
+ */
+
 export const HAS_CONTEXT = Symbol("HAS_CONTEXT");

 export interface StringContextOpaque {
@@ -143,6 +168,20 @@ export const parseContextToInfoMap = (context: NixStringContext): Map<string, Pa
  return result;
 };

+/**
+ * Extract input derivations and source paths from context
+ *
+ * IMPORTANT: Used by derivation builder to determine build dependencies.
+ *
+ * Returns:
+ * - inputDrvs: Map of derivation paths to their required output names
+ * - inputSrcs: Set of plain store paths (opaque) and drvDeep references
+ *
+ * Context type handling:
+ * - Opaque: Added to inputSrcs
+ * - DrvDeep: Added to inputSrcs (entire derivation + all outputs)
+ * - Built: Added to inputDrvs with specific output name
+ */
 export const extractInputDrvsAndSrcs = (
  context: NixStringContext,
 ): { inputDrvs: Map<string, Set<string>>; inputSrcs: Set<string> } => {
--- a/nix-js/runtime-ts/src/types/global.d.ts
+++ b/nix-js/runtime-ts/src/types/global.d.ts
@@ -35,7 +35,7 @@ declare global {
  namespace Deno {
    namespace core {
      namespace ops {
-        function op_resolve_path(path: string): string;
+        function op_resolve_path(currentDir: string, path: string): string;
        function op_import(path: string): string;
        function op_read_file(path: string): string;
        function op_path_exists(path: string): boolean;
@@ -76,6 +76,8 @@ declare global {
          recursive: boolean,
          sha256: string | null,
        ): string;
+        function op_store_path(path: string): string;
+        function op_to_file(name: string, contents: string, references: string[]): string;
      }
    }
  }
--- a/nix-js/src/bin/eval.rs
+++ b/nix-js/src/bin/eval.rs
@@ -1,8 +1,15 @@
 use anyhow::Result;
 use nix_js::context::Context;
 use std::process::exit;
+use tracing_subscriber::EnvFilter;

 fn main() -> Result<()> {
+    let format = tracing_subscriber::fmt::format().without_time();
+    tracing_subscriber::fmt()
+        .with_env_filter(EnvFilter::from_default_env())
+        .event_format(format)
+        .init();
+
    let mut args = std::env::args();
    if args.len() != 2 {
        eprintln!("Usage: {} expr", args.next().unwrap());
--- a/nix-js/src/bin/repl.rs
+++ b/nix-js/src/bin/repl.rs
@@ -1,11 +1,17 @@
 use anyhow::Result;
+use nix_js::context::Context;
 use regex::Regex;
 use rustyline::DefaultEditor;
 use rustyline::error::ReadlineError;
-
-use nix_js::context::Context;
+use tracing_subscriber::EnvFilter;

 fn main() -> Result<()> {
+    let format = tracing_subscriber::fmt::format().without_time();
+    tracing_subscriber::fmt()
+        .with_env_filter(EnvFilter::from_default_env())
+        .event_format(format)
+        .init();
+
    let mut rl = DefaultEditor::new()?;
    let mut context = Context::new()?;
    let re = Regex::new(r"^\s*([a-zA-Z_][a-zA-Z0-9_'-]*)\s*=(.*)$").unwrap();
--- a/nix-js/src/codegen.rs
+++ b/nix-js/src/codegen.rs
@@ -1,14 +1,28 @@
+use std::path::Path;
+
 use itertools::Itertools as _;

 use crate::ir::*;

-pub(crate) trait Compile<Ctx: CodegenContext> {
+pub(crate) fn compile(expr: &Ir, ctx: &impl CodegenContext) -> String {
+    let code = expr.compile(ctx);
+    let debug_prefix = if std::env::var("NIX_JS_DEBUG_THUNKS").is_ok() {
+        "Nix.DEBUG_THUNKS.enabled=true,"
+    } else {
+        ""
+    };
+    let cur_dir = ctx.get_current_dir().display().to_string().escape_quote();
+    format!("({}currentDir={},{})", debug_prefix, cur_dir, code)
+}
+
+trait Compile<Ctx: CodegenContext> {
    fn compile(&self, ctx: &Ctx) -> String;
 }

 pub(crate) trait CodegenContext {
    fn get_ir(&self, id: ExprId) -> &Ir;
    fn get_sym(&self, id: SymId) -> &str;
+    fn get_current_dir(&self) -> &Path;
 }

 trait EscapeQuote {
@@ -45,7 +59,7 @@ impl<Ctx: CodegenContext> Compile<Ctx> for Ir {
            Ir::Path(p) => {
                // Path needs runtime resolution
                let path_expr = ctx.get_ir(p.expr).compile(ctx);
-                format!("Nix.resolvePath({})", path_expr)
+                format!("Nix.resolvePath(currentDir,{})", path_expr)
            }
            &Ir::If(If { cond, consq, alter }) => {
                let cond = ctx.get_ir(cond).compile(ctx);
@@ -75,11 +89,17 @@ impl<Ctx: CodegenContext> Compile<Ctx> for Ir {
            }
            Ir::ConcatStrings(x) => x.compile(ctx),
            Ir::HasAttr(x) => x.compile(ctx),
-            &Ir::Assert(Assert { assertion, expr }) => {
+            &Ir::Assert(Assert {
+                assertion,
+                expr,
+                ref assertion_raw,
+            }) => {
                let assertion = ctx.get_ir(assertion).compile(ctx);
-                let expr_dbg = ctx.get_ir(expr);
                let expr = ctx.get_ir(expr).compile(ctx);
-                format!("({assertion})?({expr}):(()=>{{throw new Error(`assertion failed ({expr_dbg:#?})`)}})()")
+                format!(
+                    "Nix.assert({assertion},{expr},{})",
+                    assertion_raw.escape_quote()
+                )
            }
        }
    }
@@ -102,13 +122,13 @@ impl<Ctx: CodegenContext> Compile<Ctx> for BinOp {
            Leq => format!("Nix.op.lte({},{})", lhs, rhs),
            Geq => format!("Nix.op.gte({},{})", lhs, rhs),
            // Short-circuit operators: use JavaScript native && and ||
-            And => format!("Nix.force({}) && Nix.force({})", lhs, rhs),
-            Or => format!("Nix.force({}) || Nix.force({})", lhs, rhs),
-            Impl => format!("(!Nix.force({}) || Nix.force({}))", lhs, rhs),
+            And => format!("Nix.force({})&&Nix.force({})", lhs, rhs),
+            Or => format!("Nix.force({})||Nix.force({})", lhs, rhs),
+            Impl => format!("(!Nix.force({})||Nix.force({}))", lhs, rhs),
            Con => format!("Nix.op.concat({},{})", lhs, rhs),
            Upd => format!("Nix.op.update({},{})", lhs, rhs),
-            PipeL => format!("Nix.call({}, {})", rhs, lhs),
-            PipeR => format!("Nix.call({}, {})", lhs, rhs),
+            PipeL => format!("Nix.call({},{})", rhs, lhs),
+            PipeR => format!("Nix.call({},{})", lhs, rhs),
        }
    }
 }
@@ -183,7 +203,7 @@ impl<Ctx: CodegenContext> Compile<Ctx> for Call {
    fn compile(&self, ctx: &Ctx) -> String {
        let func = ctx.get_ir(self.func).compile(ctx);
        let arg = ctx.get_ir(self.arg).compile(ctx);
-        format!("Nix.call({func}, {arg})")
+        format!("Nix.call({func},{arg})")
    }
 }

@@ -231,7 +251,7 @@ impl<Ctx: CodegenContext> Compile<Ctx> for Let {
        }

        let body = ctx.get_ir(self.body).compile(ctx);
-        format!("(()=>{{{}; return {}}})()", js_statements.join(";"), body)
+        format!("(()=>{{{};return {}}})()", js_statements.join(";"), body)
    }
 }

@@ -247,9 +267,12 @@ impl<Ctx: CodegenContext> Compile<Ctx> for Select {
            })
            .join(",");
        if let Some(default) = self.default {
-            format!("Nix.selectWithDefault({lhs}, [{attrpath}], {})", ctx.get_ir(default).compile(ctx))
+            format!(
+                "Nix.selectWithDefault({lhs},[{attrpath}],{})",
+                ctx.get_ir(default).compile(ctx)
+            )
        } else {
-            format!("Nix.select({lhs}, [{attrpath}])")
+            format!("Nix.select({lhs},[{attrpath}])")
        }
    }
 }
@@ -261,16 +284,16 @@ impl<Ctx: CodegenContext> Compile<Ctx> for AttrSet {
        for (&sym, &expr) in &self.stcs {
            let key = ctx.get_sym(sym);
            let value = ctx.get_ir(expr).compile(ctx);
-            attrs.push(format!("{}: {}", key.escape_quote(), value));
+            attrs.push(format!("{}:{}", key.escape_quote(), value));
        }

        for (key_expr, value_expr) in &self.dyns {
            let key = ctx.get_ir(*key_expr).compile(ctx);
            let value = ctx.get_ir(*value_expr).compile(ctx);
-            attrs.push(format!("[{}]: {}", key, value));
+            attrs.push(format!("[{}]:{}", key, value));
        }

-        format!("{{{}}}", attrs.join(", "))
+        format!("{{{}}}", attrs.join(","))
    }
 }

@@ -308,6 +331,6 @@ impl<Ctx: CodegenContext> Compile<Ctx> for HasAttr {
                Attr::Dynamic(expr_id) => ctx.get_ir(*expr_id).compile(ctx),
            })
            .join(",");
-        format!("Nix.hasAttr({lhs}, [{attrpath}])")
+        format!("Nix.hasAttr({lhs},[{attrpath}])")
    }
 }
--- a/nix-js/src/context.rs
+++ b/nix-js/src/context.rs
@@ -1,25 +1,21 @@
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::ptr::NonNull;

-use hashbrown::HashMap;
+use hashbrown::{HashMap, HashSet};
 use itertools::Itertools as _;
+use petgraph::graphmap::DiGraphMap;
 use string_interner::DefaultStringInterner;

-use crate::codegen::{CodegenContext, Compile};
+use crate::codegen::{CodegenContext, compile};
 use crate::error::{Error, Result};
-use crate::ir::{Builtin, DowngradeContext, ExprId, Ir, SymId};
-use crate::runtime::{Runtime, RuntimeCtx};
+use crate::ir::{ArgId, Builtin, Downgrade as _, DowngradeContext, ExprId, Ir, SymId, ToIr as _};
+use crate::runtime::{Runtime, RuntimeContext};
+use crate::store::{StoreBackend, StoreConfig};
 use crate::value::Value;
-
-use downgrade::DowngradeCtx;
-use drop_guard::{PathDropGuard, PathStackProvider};
-
-mod downgrade;
-mod drop_guard;
+use std::sync::Arc;

 mod private {
    use super::*;
-    use std::ops::DerefMut;
    use std::ptr::NonNull;

    pub struct CtxPtr(NonNull<Ctx>);
@@ -36,18 +32,13 @@ mod private {
            unsafe { self.0.as_mut() }
        }
    }
-    impl PathStackProvider for CtxPtr {
-        fn path_stack(&mut self) -> &mut Vec<PathBuf> {
-            &mut self.as_mut().path_stack
-        }
-    }

-    impl RuntimeCtx for CtxPtr {
-        fn get_current_dir(&self) -> PathBuf {
+    impl RuntimeContext for CtxPtr {
+        fn get_current_dir(&self) -> &Path {
            self.as_ref().get_current_dir()
        }
-        fn push_path_stack(&mut self, path: PathBuf) -> impl DerefMut<Target = Self> {
-            PathDropGuard::new(path, self)
+        fn set_current_file(&mut self, path: PathBuf) {
+            self.as_mut().current_file = Some(path);
        }
        fn compile_code(&mut self, expr: &str) -> Result<String> {
            self.as_mut().compile_code(expr)
@@ -65,6 +56,7 @@ pub(crate) struct SccInfo {
 pub struct Context {
    ctx: Ctx,
    runtime: Runtime<CtxPtr>,
+    store: Arc<StoreBackend>,
 }

 impl Context {
@@ -72,16 +64,29 @@ impl Context {
        let ctx = Ctx::new();
        let runtime = Runtime::new()?;

-        Ok(Self { ctx, runtime })
+        let config = StoreConfig::from_env();
+        let store = Arc::new(StoreBackend::new(config)?);
+
+        Ok(Self { ctx, runtime, store })
    }

    pub fn eval_code(&mut self, expr: &str) -> Result<Value> {
-        // Initialize `path_stack` with current directory for relative path resolution
-        let mut guard = PathDropGuard::new_cwd(&mut self.ctx)?;
-        let ctx = guard.as_ctx();
+        self.ctx.current_file = Some(
+            std::env::current_dir()
+                .map_err(|err| {
+                    Error::internal(format!("Failed to get current working dir: {err}"))
+                })?
+                .join("__eval__.nix"),
+        );
+        let code = self.compile_code(expr)?;

-        let code = ctx.compile_code(expr)?;
-        self.runtime.eval(format!("Nix.force({code})"), CtxPtr::new(&mut self.ctx))
+        self.runtime
+            .op_state()
+            .borrow_mut()
+            .put(self.store.clone());
+
+        self.runtime
+            .eval(format!("Nix.force({code})"), CtxPtr::new(&mut self.ctx))
    }

    pub fn compile_code(&mut self, expr: &str) -> Result<String> {
@@ -92,13 +97,17 @@ impl Context {
    pub(crate) fn eval_js(&mut self, code: String) -> Result<Value> {
        self.runtime.eval(code, CtxPtr::new(&mut self.ctx))
    }
+
+    pub fn get_store_dir(&self) -> &str {
+        self.store.as_store().get_store_dir()
+    }
 }

 pub(crate) struct Ctx {
    irs: Vec<Ir>,
    symbols: DefaultStringInterner,
    global: NonNull<HashMap<SymId, ExprId>>,
-    path_stack: Vec<PathBuf>,
+    current_file: Option<PathBuf>,
 }

 impl Default for Ctx {
@@ -159,7 +168,7 @@ impl Default for Ctx {
            symbols,
            irs,
            global: unsafe { NonNull::new_unchecked(Box::leak(Box::new(global))) },
-            path_stack: Vec::new(),
+            current_file: None,
        }
    }
 }
@@ -174,15 +183,12 @@ impl Ctx {
        DowngradeCtx::new(self, global_ref)
    }

-    pub(crate) fn get_current_dir(&self) -> PathBuf {
-        self.path_stack
-            .last()
-            .expect(
-                "path_stack should never be empty when get_current_dir is called. this is a bug",
-            )
+    pub(crate) fn get_current_dir(&self) -> &Path {
+        self.current_file
+            .as_ref()
+            .expect("current_file is not set")
            .parent()
-            .expect("path in path_stack should always have a parent dir. this is a bug")
-            .to_path_buf()
+            .expect("current_file doesn't have a parent dir")
    }

    fn compile_code(&mut self, expr: &str) -> Result<String> {
@@ -196,16 +202,8 @@ impl Ctx {
        let root = self
            .downgrade_ctx()
            .downgrade(root.tree().expr().unwrap())?;
-        let code = self.get_ir(root).compile(self);
-
-        let debug_prefix = if std::env::var("NIX_JS_DEBUG_THUNKS").is_ok() {
-            "Nix.DEBUG_THUNKS.enabled=true,"
-        } else {
-            ""
-        };
-        let code = format!("({}{})", debug_prefix, code);
-        #[cfg(debug_assertions)]
-        eprintln!("[DEBUG] generated code: {}", &code);
+        let code = compile(self.get_ir(root), self);
+        tracing::debug!("generated code: {}", &code);
        Ok(code)
    }
 }
@@ -214,14 +212,301 @@ impl CodegenContext for Ctx {
    fn get_ir(&self, id: ExprId) -> &Ir {
        self.irs.get(id.0).expect("ExprId out of bounds")
    }
-
    fn get_sym(&self, id: SymId) -> &str {
        self.symbols.resolve(id).expect("SymId out of bounds")
    }
-}
-
-impl PathStackProvider for Ctx {
-    fn path_stack(&mut self) -> &mut Vec<PathBuf> {
-        &mut self.path_stack
+    fn get_current_dir(&self) -> &std::path::Path {
+        self.get_current_dir()
+    }
+}
+
+struct DependencyTracker {
+    graph: DiGraphMap<ExprId, ()>,
+    current_binding: Option<ExprId>,
+    let_scope_exprs: HashSet<ExprId>,
+    // The outer binding that owns this tracker (for nested let scopes in function params)
+    owner_binding: Option<ExprId>,
+}
+
+enum Scope<'ctx> {
+    Global(&'ctx HashMap<SymId, ExprId>),
+    Let(HashMap<SymId, ExprId>),
+    Param(SymId, ExprId),
+    With(ExprId),
+}
+
+struct ScopeGuard<'a, 'ctx> {
+    ctx: &'a mut DowngradeCtx<'ctx>,
+}
+
+impl<'a, 'ctx> Drop for ScopeGuard<'a, 'ctx> {
+    fn drop(&mut self) {
+        self.ctx.scopes.pop();
+    }
+}
+
+impl<'a, 'ctx> ScopeGuard<'a, 'ctx> {
+    fn as_ctx(&mut self) -> &mut DowngradeCtx<'ctx> {
+        self.ctx
+    }
+}
+
+pub struct DowngradeCtx<'ctx> {
+    ctx: &'ctx mut Ctx,
+    irs: Vec<Option<Ir>>,
+    scopes: Vec<Scope<'ctx>>,
+    arg_id: usize,
+    dep_tracker_stack: Vec<DependencyTracker>,
+}
+
+impl<'ctx> DowngradeCtx<'ctx> {
+    fn new(ctx: &'ctx mut Ctx, global: &'ctx HashMap<SymId, ExprId>) -> Self {
+        Self {
+            scopes: vec![Scope::Global(global)],
+            irs: vec![],
+            arg_id: 0,
+            dep_tracker_stack: Vec::new(),
+            ctx,
+        }
+    }
+}
+
+impl DowngradeContext for DowngradeCtx<'_> {
+    fn new_expr(&mut self, expr: Ir) -> ExprId {
+        self.irs.push(Some(expr));
+        ExprId(self.ctx.irs.len() + self.irs.len() - 1)
+    }
+
+    fn new_arg(&mut self) -> ExprId {
+        self.irs.push(Some(Ir::Arg(ArgId(self.arg_id))));
+        self.arg_id += 1;
+        ExprId(self.ctx.irs.len() + self.irs.len() - 1)
+    }
+
+    fn new_sym(&mut self, sym: String) -> SymId {
+        self.ctx.symbols.get_or_intern(sym)
+    }
+
+    fn get_sym(&self, id: SymId) -> &str {
+        self.ctx.get_sym(id)
+    }
+
+    fn lookup(&mut self, sym: SymId) -> Result<ExprId> {
+        for scope in self.scopes.iter().rev() {
+            match scope {
+                &Scope::Global(global_scope) => {
+                    if let Some(&expr) = global_scope.get(&sym) {
+                        return Ok(expr);
+                    }
+                }
+                Scope::Let(let_scope) => {
+                    if let Some(&expr) = let_scope.get(&sym) {
+                        // Find which tracker contains this expression
+                        let expr_tracker_idx = self
+                            .dep_tracker_stack
+                            .iter()
+                            .position(|t| t.let_scope_exprs.contains(&expr));
+
+                        // Find the innermost tracker with a current_binding
+                        let current_tracker_idx = self
+                            .dep_tracker_stack
+                            .iter()
+                            .rposition(|t| t.current_binding.is_some());
+
+                        // Record dependency if both exist
+                        if let (Some(expr_idx), Some(curr_idx)) =
+                            (expr_tracker_idx, current_tracker_idx)
+                        {
+                            let current_binding = self.dep_tracker_stack[curr_idx]
+                                .current_binding
+                                .expect("current_binding not set");
+                            let owner_binding = self.dep_tracker_stack[curr_idx].owner_binding;
+
+                            // If referencing from inner scope to outer scope
+                            if curr_idx >= expr_idx {
+                                let tracker = &mut self.dep_tracker_stack[expr_idx];
+                                let from_node = current_binding;
+                                let to_node = expr;
+                                if curr_idx > expr_idx {
+                                    // Cross-scope reference: use owner_binding if available
+                                    if let Some(owner) = owner_binding {
+                                        tracker.graph.add_edge(owner, expr, ());
+                                    }
+                                } else {
+                                    // Same-level reference: record directly
+                                    tracker.graph.add_edge(from_node, to_node, ());
+                                }
+                            }
+                        }
+
+                        return Ok(self.new_expr(Ir::ExprRef(expr)));
+                    }
+                }
+                &Scope::Param(param_sym, expr) => {
+                    if param_sym == sym {
+                        return Ok(expr);
+                    }
+                }
+                &Scope::With(_) => (),
+            }
+        }
+
+        let namespaces: Vec<ExprId> = self
+            .scopes
+            .iter()
+            .filter_map(|scope| {
+                if let &Scope::With(namespace) = scope {
+                    Some(namespace)
+                } else {
+                    None
+                }
+            })
+            .collect();
+        let mut result = None;
+        for namespace in namespaces {
+            use crate::ir::{Attr, Select};
+            let select = Select {
+                expr: namespace,
+                attrpath: vec![Attr::Str(sym)],
+                default: result, // Link to outer With or None
+            };
+            result = Some(self.new_expr(select.to_ir()));
+        }
+        result.ok_or_else(|| Error::downgrade_error(format!("'{}' not found", self.get_sym(sym))))
+    }
+
+    fn extract_expr(&mut self, id: ExprId) -> Ir {
+        let local_id = id.0 - self.ctx.irs.len();
+        self.irs
+            .get_mut(local_id)
+            .expect("ExprId out of bounds")
+            .take()
+            .expect("extract_expr called on an already extracted expr")
+    }
+
+    fn replace_expr(&mut self, id: ExprId, expr: Ir) {
+        let local_id = id.0 - self.ctx.irs.len();
+        let _ = self
+            .irs
+            .get_mut(local_id)
+            .expect("ExprId out of bounds")
+            .insert(expr);
+    }
+
+    #[allow(refining_impl_trait)]
+    fn reserve_slots(&mut self, slots: usize) -> impl Iterator<Item = ExprId> + Clone + use<> {
+        let start = self.ctx.irs.len() + self.irs.len();
+        self.irs.extend(std::iter::repeat_with(|| None).take(slots));
+        (start..start + slots).map(ExprId)
+    }
+
+    fn downgrade(mut self, root: rnix::ast::Expr) -> Result<ExprId> {
+        let root = root.downgrade(&mut self)?;
+        self.ctx
+            .irs
+            .extend(self.irs.into_iter().map(Option::unwrap));
+        Ok(root)
+    }
+
+    fn with_let_scope<F, R>(&mut self, bindings: HashMap<SymId, ExprId>, f: F) -> R
+    where
+        F: FnOnce(&mut Self) -> R,
+    {
+        self.scopes.push(Scope::Let(bindings));
+        let mut guard = ScopeGuard { ctx: self };
+        f(guard.as_ctx())
+    }
+
+    fn with_param_scope<F, R>(&mut self, param: SymId, arg: ExprId, f: F) -> R
+    where
+        F: FnOnce(&mut Self) -> R,
+    {
+        self.scopes.push(Scope::Param(param, arg));
+        let mut guard = ScopeGuard { ctx: self };
+        f(guard.as_ctx())
+    }
+
+    fn with_with_scope<F, R>(&mut self, namespace: ExprId, f: F) -> R
+    where
+        F: FnOnce(&mut Self) -> R,
+    {
+        self.scopes.push(Scope::With(namespace));
+        let mut guard = ScopeGuard { ctx: self };
+        f(guard.as_ctx())
+    }
+
+    fn push_dep_tracker(&mut self, slots: &[ExprId]) {
+        let mut graph = DiGraphMap::new();
+        let mut let_scope_exprs = HashSet::new();
+
+        for &expr in slots.iter() {
+            graph.add_node(expr);
+            let_scope_exprs.insert(expr);
+        }
+
+        self.dep_tracker_stack.push(DependencyTracker {
+            graph,
+            current_binding: None,
+            let_scope_exprs,
+            owner_binding: None,
+        });
+    }
+
+    fn push_dep_tracker_with_owner(&mut self, slots: &[ExprId], owner: ExprId) {
+        let mut graph = DiGraphMap::new();
+        let mut let_scope_exprs = HashSet::new();
+
+        for &expr in slots.iter() {
+            graph.add_node(expr);
+            let_scope_exprs.insert(expr);
+        }
+
+        self.dep_tracker_stack.push(DependencyTracker {
+            graph,
+            current_binding: None,
+            let_scope_exprs,
+            owner_binding: Some(owner),
+        });
+    }
+
+    fn get_current_binding(&self) -> Option<ExprId> {
+        self.dep_tracker_stack
+            .last()
+            .and_then(|t| t.current_binding)
+    }
+
+    fn set_current_binding(&mut self, expr: Option<ExprId>) {
+        if let Some(tracker) = self.dep_tracker_stack.last_mut() {
+            tracker.current_binding = expr;
+        }
+    }
+
+    fn pop_dep_tracker(&mut self) -> Result<SccInfo> {
+        let tracker = self
+            .dep_tracker_stack
+            .pop()
+            .expect("pop_dep_tracker without active tracker");
+
+        use petgraph::algo::kosaraju_scc;
+        let sccs = kosaraju_scc(&tracker.graph);
+
+        let mut sccs_topo = Vec::new();
+
+        for scc_nodes in sccs.iter() {
+            let mut scc_exprs = Vec::new();
+            let mut is_recursive = scc_nodes.len() > 1;
+
+            for &expr in scc_nodes {
+                scc_exprs.push(expr);
+
+                if !is_recursive && tracker.graph.contains_edge(expr, expr) {
+                    is_recursive = true;
+                }
+            }
+
+            sccs_topo.push((scc_exprs, is_recursive));
+        }
+
+        Ok(SccInfo { sccs: sccs_topo })
    }
 }
--- a/nix-js/src/context/downgrade.rs
+++ b/nix-js/src/context/downgrade.rs
@@ -1,315 +0,0 @@
-use hashbrown::HashMap;
-use hashbrown::HashSet;
-use petgraph::Directed;
-use petgraph::Graph;
-use petgraph::graph::NodeIndex;
-
-use crate::codegen::CodegenContext;
-use crate::error::{Error, Result};
-use crate::ir::{ArgId, Downgrade, DowngradeContext, ExprId, Ir, SymId, ToIr};
-
-use super::{Ctx, SccInfo};
-
-struct DependencyTracker {
-    expr_to_node: HashMap<ExprId, NodeIndex>,
-    graph: Graph<ExprId, (), Directed>,
-    current_binding: Option<ExprId>,
-    let_scope_exprs: HashSet<ExprId>,
-    // The outer binding that owns this tracker (for nested let scopes in function params)
-    owner_binding: Option<ExprId>,
-}
-
-enum Scope<'ctx> {
-    Global(&'ctx HashMap<SymId, ExprId>),
-    Let(HashMap<SymId, ExprId>),
-    Param(SymId, ExprId),
-    With(ExprId),
-}
-
-struct ScopeGuard<'a, 'ctx> {
-    ctx: &'a mut DowngradeCtx<'ctx>,
-}
-
-impl<'a, 'ctx> Drop for ScopeGuard<'a, 'ctx> {
-    fn drop(&mut self) {
-        self.ctx.scopes.pop();
-    }
-}
-
-impl<'a, 'ctx> ScopeGuard<'a, 'ctx> {
-    fn as_ctx(&mut self) -> &mut DowngradeCtx<'ctx> {
-        self.ctx
-    }
-}
-
-pub struct DowngradeCtx<'ctx> {
-    ctx: &'ctx mut Ctx,
-    irs: Vec<Option<Ir>>,
-    scopes: Vec<Scope<'ctx>>,
-    arg_id: usize,
-    dep_tracker_stack: Vec<DependencyTracker>,
-}
-
-impl<'ctx> DowngradeCtx<'ctx> {
-    pub fn new(ctx: &'ctx mut Ctx, global: &'ctx HashMap<SymId, ExprId>) -> Self {
-        Self {
-            scopes: vec![Scope::Global(global)],
-            irs: vec![],
-            arg_id: 0,
-            dep_tracker_stack: Vec::new(),
-            ctx,
-        }
-    }
-}
-
-impl DowngradeContext for DowngradeCtx<'_> {
-    fn new_expr(&mut self, expr: Ir) -> ExprId {
-        self.irs.push(Some(expr));
-        ExprId(self.ctx.irs.len() + self.irs.len() - 1)
-    }
-
-    fn new_arg(&mut self) -> ExprId {
-        self.irs.push(Some(Ir::Arg(ArgId(self.arg_id))));
-        self.arg_id += 1;
-        ExprId(self.ctx.irs.len() + self.irs.len() - 1)
-    }
-
-    fn new_sym(&mut self, sym: String) -> SymId {
-        self.ctx.symbols.get_or_intern(sym)
-    }
-
-    fn get_sym(&self, id: SymId) -> &str {
-        self.ctx.get_sym(id)
-    }
-
-    fn lookup(&mut self, sym: SymId) -> Result<ExprId> {
-        for scope in self.scopes.iter().rev() {
-            match scope {
-                &Scope::Global(global_scope) => {
-                    if let Some(&expr) = global_scope.get(&sym) {
-                        return Ok(expr);
-                    }
-                }
-                Scope::Let(let_scope) => {
-                    if let Some(&expr) = let_scope.get(&sym) {
-                        // Find which tracker contains this expression
-                        let expr_tracker_idx = self
-                            .dep_tracker_stack
-                            .iter()
-                            .position(|t| t.let_scope_exprs.contains(&expr));
-
-                        // Find the innermost tracker with a current_binding
-                        let current_tracker_idx = self
-                            .dep_tracker_stack
-                            .iter()
-                            .rposition(|t| t.current_binding.is_some());
-
-                        // Record dependency if both exist
-                        if let (Some(expr_idx), Some(curr_idx)) =
-                            (expr_tracker_idx, current_tracker_idx)
-                        {
-                            let current_binding =
-                                self.dep_tracker_stack[curr_idx].current_binding.unwrap();
-                            let owner_binding = self.dep_tracker_stack[curr_idx].owner_binding;
-
-                            // If referencing from inner scope to outer scope
-                            if curr_idx >= expr_idx {
-                                let tracker = &mut self.dep_tracker_stack[expr_idx];
-                                if let (Some(&from_node), Some(&to_node)) = (
-                                    tracker.expr_to_node.get(&current_binding),
-                                    tracker.expr_to_node.get(&expr),
-                                ) {
-                                    // Same-level reference: record directly
-                                    tracker.graph.add_edge(from_node, to_node, ());
-                                } else if curr_idx > expr_idx {
-                                    // Cross-scope reference: use owner_binding if available
-                                    if let Some(owner) = owner_binding
-                                        && let (Some(&from_node), Some(&to_node)) = (
-                                            tracker.expr_to_node.get(&owner),
-                                            tracker.expr_to_node.get(&expr),
-                                        )
-                                    {
-                                        tracker.graph.add_edge(from_node, to_node, ());
-                                    }
-                                }
-                            }
-                        }
-
-                        return Ok(self.new_expr(Ir::ExprRef(expr)));
-                    }
-                }
-                &Scope::Param(param_sym, expr) => {
-                    if param_sym == sym {
-                        return Ok(expr);
-                    }
-                }
-                &Scope::With(_) => (),
-            }
-        }
-
-        let namespaces: Vec<ExprId> = self
-            .scopes
-            .iter()
-            .filter_map(|scope| {
-                if let &Scope::With(namespace) = scope {
-                    Some(namespace)
-                } else {
-                    None
-                }
-            })
-            .collect();
-        let mut result = None;
-        for namespace in namespaces {
-            use crate::ir::{Attr, Select};
-            let select = Select {
-                expr: namespace,
-                attrpath: vec![Attr::Str(sym)],
-                default: result, // Link to outer With or None
-            };
-            result = Some(self.new_expr(select.to_ir()));
-        }
-        result.ok_or_else(|| Error::downgrade_error(format!("'{}' not found", self.get_sym(sym))))
-    }
-
-    fn extract_expr(&mut self, id: ExprId) -> Ir {
-        let local_id = id.0 - self.ctx.irs.len();
-        self.irs
-            .get_mut(local_id)
-            .expect("ExprId out of bounds")
-            .take()
-            .expect("extract_expr called on an already extracted expr")
-    }
-
-    fn replace_expr(&mut self, id: ExprId, expr: Ir) {
-        let local_id = id.0 - self.ctx.irs.len();
-        let _ = self
-            .irs
-            .get_mut(local_id)
-            .expect("ExprId out of bounds")
-            .insert(expr);
-    }
-
-    #[allow(refining_impl_trait)]
-    fn reserve_slots(&mut self, slots: usize) -> impl Iterator<Item = ExprId> + Clone + use<> {
-        let start = self.ctx.irs.len() + self.irs.len();
-        self.irs.extend(std::iter::repeat_with(|| None).take(slots));
-        (start..start + slots).map(ExprId)
-    }
-
-    fn downgrade(mut self, root: rnix::ast::Expr) -> Result<ExprId> {
-        let root = root.downgrade(&mut self)?;
-        self.ctx
-            .irs
-            .extend(self.irs.into_iter().map(Option::unwrap));
-        Ok(root)
-    }
-
-    fn with_let_scope<F, R>(&mut self, bindings: HashMap<SymId, ExprId>, f: F) -> R
-    where
-        F: FnOnce(&mut Self) -> R,
-    {
-        self.scopes.push(Scope::Let(bindings));
-        let mut guard = ScopeGuard { ctx: self };
-        f(guard.as_ctx())
-    }
-
-    fn with_param_scope<F, R>(&mut self, param: SymId, arg: ExprId, f: F) -> R
-    where
-        F: FnOnce(&mut Self) -> R,
-    {
-        self.scopes.push(Scope::Param(param, arg));
-        let mut guard = ScopeGuard { ctx: self };
-        f(guard.as_ctx())
-    }
-
-    fn with_with_scope<F, R>(&mut self, namespace: ExprId, f: F) -> R
-    where
-        F: FnOnce(&mut Self) -> R,
-    {
-        self.scopes.push(Scope::With(namespace));
-        let mut guard = ScopeGuard { ctx: self };
-        f(guard.as_ctx())
-    }
-
-    fn push_dep_tracker(&mut self, slots: &[ExprId]) {
-        let mut graph = Graph::new();
-        let mut expr_to_node = HashMap::new();
-        let mut let_scope_exprs = HashSet::new();
-
-        for &expr in slots.iter() {
-            let node = graph.add_node(expr);
-            expr_to_node.insert(expr, node);
-            let_scope_exprs.insert(expr);
-        }
-
-        self.dep_tracker_stack.push(DependencyTracker {
-            expr_to_node,
-            graph,
-            current_binding: None,
-            let_scope_exprs,
-            owner_binding: None,
-        });
-    }
-
-    fn push_dep_tracker_with_owner(&mut self, slots: &[ExprId], owner: ExprId) {
-        let mut graph = Graph::new();
-        let mut expr_to_node = HashMap::new();
-        let mut let_scope_exprs = HashSet::new();
-
-        for &expr in slots.iter() {
-            let node = graph.add_node(expr);
-            expr_to_node.insert(expr, node);
-            let_scope_exprs.insert(expr);
-        }
-
-        self.dep_tracker_stack.push(DependencyTracker {
-            expr_to_node,
-            graph,
-            current_binding: None,
-            let_scope_exprs,
-            owner_binding: Some(owner),
-        });
-    }
-
-    fn get_current_binding(&self) -> Option<ExprId> {
-        self.dep_tracker_stack
-            .last()
-            .and_then(|t| t.current_binding)
-    }
-
-    fn set_current_binding(&mut self, expr: Option<ExprId>) {
-        if let Some(tracker) = self.dep_tracker_stack.last_mut() {
-            tracker.current_binding = expr;
-        }
-    }
-
-    fn pop_dep_tracker(&mut self) -> Result<SccInfo> {
-        let tracker = self
-            .dep_tracker_stack
-            .pop()
-            .expect("pop_dep_tracker without active tracker");
-
-        use petgraph::algo::kosaraju_scc;
-        let sccs = kosaraju_scc(&tracker.graph);
-
-        let mut sccs_topo = Vec::new();
-
-        for scc_nodes in sccs.iter() {
-            let mut scc_exprs = Vec::new();
-            let mut is_recursive = scc_nodes.len() > 1;
-
-            for &node_idx in scc_nodes {
-                let expr = tracker.graph[node_idx];
-                scc_exprs.push(expr);
-
-                if !is_recursive && tracker.graph.contains_edge(node_idx, node_idx) {
-                    is_recursive = true;
-                }
-            }
-
-            sccs_topo.push((scc_exprs, is_recursive));
-        }
-
-        Ok(SccInfo { sccs: sccs_topo })
-    }
-}
--- a/nix-js/src/context/drop_guard.rs
+++ b/nix-js/src/context/drop_guard.rs
@@ -1,41 +0,0 @@
-use std::ops::{Deref, DerefMut};
-use std::path::PathBuf;
-
-use crate::error::{Error, Result};
-
-pub trait PathStackProvider {
-    fn path_stack(&mut self) -> &mut Vec<PathBuf>;
-}
-
-pub struct PathDropGuard<'ctx, Ctx: PathStackProvider> {
-    ctx: &'ctx mut Ctx,
-}
-
-impl<'ctx, Ctx: PathStackProvider> PathDropGuard<'ctx, Ctx> {
-    pub fn new(path: PathBuf, ctx: &'ctx mut Ctx) -> Self {
-        ctx.path_stack().push(path);
-        Self { ctx }
-    }
-    pub fn new_cwd(ctx: &'ctx mut Ctx) -> Result<Self> {
-        let cwd = std::env::current_dir()
-            .map_err(|err| Error::downgrade_error(format!("cannot get cwd: {err}")))?;
-        let virtual_file = cwd.join("__eval__.nix");
-        ctx.path_stack().push(virtual_file);
-        Ok(Self { ctx })
-    }
-    pub fn as_ctx(&mut self) -> &mut Ctx {
-        self.ctx
-    }
-}
-
-impl<Ctx: PathStackProvider> Deref for PathDropGuard<'_, Ctx> {
-    type Target = Ctx;
-    fn deref(&self) -> &Self::Target {
-        self.ctx
-    }
-}
-impl<Ctx: PathStackProvider> DerefMut for PathDropGuard<'_, Ctx> {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        self.ctx
-    }
-}
--- a/nix-js/src/fetcher.rs
+++ b/nix-js/src/fetcher.rs
@@ -1,17 +1,21 @@
+use std::sync::Arc;
+
+use deno_core::{OpState, op2};
+use serde::Serialize;
+use tracing::debug;
+
 mod archive;
-mod cache;
+pub(crate) mod cache;
 mod download;
 mod git;
 mod hg;
-mod nar;

 pub use cache::FetcherCache;
 pub use download::Downloader;

-use deno_core::op2;
-use serde::Serialize;
-
 use crate::runtime::NixError;
+use crate::store::StoreBackend;
+use crate::nar;

 #[derive(Serialize)]
 pub struct FetchUrlResult {
@@ -55,8 +59,7 @@ pub fn op_fetch_url(
    #[string] name: Option<String>,
    executable: bool,
 ) -> Result<FetchUrlResult, NixError> {
-    #[cfg(debug_assertions)]
-    eprintln!("[DEBUG] fetchurl: {}", url);
+    debug!("fetchurl: {}", url);
    let cache = FetcherCache::new().map_err(|e| NixError::from(e.to_string()))?;
    let downloader = Downloader::new();

@@ -101,13 +104,17 @@ pub fn op_fetch_url(
 #[op2]
 #[serde]
 pub fn op_fetch_tarball(
+    state: &mut OpState,
    #[string] url: String,
    #[string] expected_hash: Option<String>,
    #[string] expected_nar_hash: Option<String>,
    #[string] name: Option<String>,
 ) -> Result<FetchTarballResult, NixError> {
-    #[cfg(debug_assertions)]
-    eprintln!("[DEBUG] fetchTarball: url={}, expected_hash={:?}, expected_nar_hash={:?}", url, expected_hash, expected_nar_hash);
+    debug!(
+        "fetchTarball: url={}, expected_hash={:?}, expected_nar_hash={:?}",
+        url, expected_hash, expected_nar_hash
+    );
+    let store = state.borrow::<Arc<StoreBackend>>();
    let cache = FetcherCache::new().map_err(|e| NixError::from(e.to_string()))?;
    let downloader = Downloader::new();

@@ -116,37 +123,37 @@ pub fn op_fetch_tarball(
    // Try cache lookup with narHash if provided
    if let Some(ref nar_hash) = expected_nar_hash {
        let normalized = normalize_hash(nar_hash);
-        #[cfg(debug_assertions)]
-        eprintln!("[DEBUG] fetchTarball: normalized nar_hash={}", normalized);
+        debug!("fetchTarball: normalized nar_hash={}", normalized);
        if let Some(cached) = cache.get_extracted_tarball(&url, &normalized) {
-            #[cfg(debug_assertions)]
-            eprintln!("[DEBUG] fetchTarball: cache HIT (with expected nar_hash)");
+            debug!("fetchTarball: cache HIT (with expected nar_hash)");
            // Need to compute tarball hash if not cached
-            let tarball_hash = expected_hash.as_ref()
+            let tarball_hash = expected_hash
+                .as_ref()
                .map(|h| normalize_hash(h))
-                .unwrap_or_else(|| "".to_string());
+                .unwrap_or_default();
            return Ok(FetchTarballResult {
                store_path: cached.to_string_lossy().to_string(),
                hash: tarball_hash,
                nar_hash: normalized,
            });
        }
-        #[cfg(debug_assertions)]
-        eprintln!("[DEBUG] fetchTarball: cache MISS, downloading...");
+        debug!("fetchTarball: cache MISS, downloading...");
    } else if let Some((cached, cached_nar_hash)) = cache.get_extracted_tarball_by_url(&url) {
-        #[cfg(debug_assertions)]
-        eprintln!("[DEBUG] fetchTarball: cache HIT (by URL, nar_hash={})", cached_nar_hash);
-        let tarball_hash = expected_hash.as_ref()
+        debug!(
+            "fetchTarball: cache HIT (by URL, nar_hash={})",
+            cached_nar_hash
+        );
+        let tarball_hash = expected_hash
+            .as_ref()
            .map(|h| normalize_hash(h))
-            .unwrap_or_else(|| "".to_string());
+            .unwrap_or_default();
        return Ok(FetchTarballResult {
            store_path: cached.to_string_lossy().to_string(),
            hash: tarball_hash,
            nar_hash: cached_nar_hash,
        });
    }
-    #[cfg(debug_assertions)]
-    eprintln!("[DEBUG] fetchTarball: cache MISS, downloading...");
+    debug!("fetchTarball: cache MISS, downloading...");

    let data = downloader
        .download(&url)
@@ -174,8 +181,10 @@ pub fn op_fetch_tarball(
    let nar_hash =
        nar::compute_nar_hash(&extracted_path).map_err(|e| NixError::from(e.to_string()))?;

-    #[cfg(debug_assertions)]
-    eprintln!("[DEBUG] fetchTarball: computed tarball_hash={}, nar_hash={}", tarball_hash, nar_hash);
+    debug!(
+        "fetchTarball: computed tarball_hash={}, nar_hash={}",
+        tarball_hash, nar_hash
+    );

    // Verify NAR hash if provided
    if let Some(ref expected) = expected_nar_hash {
@@ -189,12 +198,13 @@ pub fn op_fetch_tarball(
        }
    }

-    let store_path = cache
-        .put_tarball_from_extracted(&url, &nar_hash, &extracted_path, &dir_name)
-        .map_err(|e| NixError::from(e.to_string()))?;
+    // let store_path = cache
+    //     .put_tarball_from_extracted(&url, &nar_hash, &extracted_path, &dir_name)
+    //     .map_err(|e| NixError::from(e.to_string()))?;
+    let store_path = store.as_store().put_directory(&dir_name, &extracted_path).unwrap();

    Ok(FetchTarballResult {
-        store_path: store_path.to_string_lossy().to_string(),
+        store_path,
        hash: tarball_hash,
        nar_hash,
    })
@@ -211,8 +221,7 @@ pub fn op_fetch_git(
    all_refs: bool,
    #[string] name: Option<String>,
 ) -> Result<FetchGitResult, NixError> {
-    #[cfg(debug_assertions)]
-    eprintln!("[DEBUG] fetchGit: {} (ref: {:?}, rev: {:?})", url, git_ref, rev);
+    debug!("fetchGit: {} (ref: {:?}, rev: {:?})", url, git_ref, rev);
    let cache = FetcherCache::new().map_err(|e| NixError::from(e.to_string()))?;
    let dir_name = name.unwrap_or_else(|| "source".to_string());

--- a/nix-js/src/fetcher/archive.rs
+++ b/nix-js/src/fetcher/archive.rs
@@ -186,7 +186,6 @@ fn copy_dir_recursive(src: &Path, dst: &Path) -> Result<(), std::io::Error> {
 pub enum ArchiveError {
    IoError(std::io::Error),
    ZipError(zip::result::ZipError),
-    UnsupportedFormat(String),
 }

 impl std::fmt::Display for ArchiveError {
@@ -194,9 +193,6 @@ impl std::fmt::Display for ArchiveError {
        match self {
            ArchiveError::IoError(e) => write!(f, "I/O error: {}", e),
            ArchiveError::ZipError(e) => write!(f, "ZIP error: {}", e),
-            ArchiveError::UnsupportedFormat(fmt) => {
-                write!(f, "Unsupported archive format: {}", fmt)
-            }
        }
    }
 }
--- a/nix-js/src/fetcher/cache.rs
+++ b/nix-js/src/fetcher/cache.rs
@@ -1,8 +1,9 @@
 use std::fs::{self, File};
 use std::io::Write;
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};

 use serde::{Deserialize, Serialize};
+use tracing::debug;

 use super::archive::ArchiveError;

@@ -168,37 +169,36 @@ impl FetcherCache {
        let meta_path = cache_dir.join(&key).join(".meta");
        let data_dir = cache_dir.join(&key);

-        #[cfg(debug_assertions)]
-        eprintln!("[CACHE] get_tarball: url={}, expected_hash={}", url, expected_hash);
+        debug!("get_tarball: url={}, expected_hash={}", url, expected_hash);

        if !meta_path.exists() || !data_dir.exists() {
-            #[cfg(debug_assertions)]
-            eprintln!("[CACHE] get_tarball: cache miss - meta or data dir not found");
+            debug!("get_tarball: cache miss - meta or data dir not found");
            return None;
        }

        let meta: CacheMetadata =
            serde_json::from_str(&fs::read_to_string(&meta_path).ok()?).ok()?;

-        #[cfg(debug_assertions)]
-        eprintln!("[CACHE] get_tarball: cached hash={}, name={}", meta.hash, meta.name);
+        debug!("get_tarball: cached hash={}, name={}", meta.hash, meta.name);

        if meta.hash == expected_hash {
            let store_path = self.make_store_path(&meta.hash, &meta.name);
-            #[cfg(debug_assertions)]
-            eprintln!("[CACHE] get_tarball: hash match, checking store_path={}", store_path.display());
+            debug!(
+                "get_tarball: hash match, checking store_path={}",
+                store_path.display()
+            );
            if store_path.exists() {
-                #[cfg(debug_assertions)]
-                eprintln!("[CACHE] get_tarball: HIT - returning store path");
+                debug!("get_tarball: HIT - returning store path");
                Some(store_path)
            } else {
-                #[cfg(debug_assertions)]
-                eprintln!("[CACHE] get_tarball: store path doesn't exist");
+                debug!("get_tarball: store path doesn't exist");
                None
            }
        } else {
-            #[cfg(debug_assertions)]
-            eprintln!("[CACHE] get_tarball: hash mismatch (cached={}, expected={})", meta.hash, expected_hash);
+            debug!(
+                "get_tarball: hash mismatch (cached={}, expected={})",
+                meta.hash, expected_hash
+            );
            None
        }
    }
@@ -241,37 +241,42 @@ impl FetcherCache {
        let meta_path = cache_entry_dir.join(".meta");
        let cached_content = cache_entry_dir.join("content");

-        #[cfg(debug_assertions)]
-        eprintln!("[CACHE] get_extracted_tarball: url={}, expected_nar_hash={}", url, expected_nar_hash);
+        debug!(
+            "get_extracted_tarball: url={}, expected_nar_hash={}",
+            url, expected_nar_hash
+        );

        if !meta_path.exists() || !cached_content.exists() {
-            #[cfg(debug_assertions)]
-            eprintln!("[CACHE] get_extracted_tarball: cache miss - meta or content dir not found");
+            debug!("get_extracted_tarball: cache miss - meta or content dir not found");
            return None;
        }

        let meta: CacheMetadata =
            serde_json::from_str(&fs::read_to_string(&meta_path).ok()?).ok()?;

-        #[cfg(debug_assertions)]
-        eprintln!("[CACHE] get_extracted_tarball: cached hash={}, name={}", meta.hash, meta.name);
+        debug!(
+            "get_extracted_tarball: cached hash={}, name={}",
+            meta.hash, meta.name
+        );

        if meta.hash == expected_nar_hash {
            let store_path = self.make_store_path(&meta.hash, &meta.name);
-            #[cfg(debug_assertions)]
-            eprintln!("[CACHE] get_extracted_tarball: hash match, checking store_path={}", store_path.display());
+            debug!(
+                "get_extracted_tarball: hash match, checking store_path={}",
+                store_path.display()
+            );
            if store_path.exists() {
-                #[cfg(debug_assertions)]
-                eprintln!("[CACHE] get_extracted_tarball: HIT - returning store path");
+                debug!("get_extracted_tarball: HIT - returning store path");
                Some(store_path)
            } else {
-                #[cfg(debug_assertions)]
-                eprintln!("[CACHE] get_extracted_tarball: store path doesn't exist");
+                debug!("get_extracted_tarball: store path doesn't exist");
                None
            }
        } else {
-            #[cfg(debug_assertions)]
-            eprintln!("[CACHE] get_extracted_tarball: hash mismatch (cached={}, expected={})", meta.hash, expected_nar_hash);
+            debug!(
+                "get_extracted_tarball: hash mismatch (cached={}, expected={})",
+                meta.hash, expected_nar_hash
+            );
            None
        }
    }
@@ -283,29 +288,27 @@ impl FetcherCache {
        let meta_path = cache_entry_dir.join(".meta");
        let cached_content = cache_entry_dir.join("content");

-        #[cfg(debug_assertions)]
-        eprintln!("[CACHE] get_extracted_tarball_by_url: url={}", url);
+        debug!("get_extracted_tarball_by_url: url={}", url);

        if !meta_path.exists() || !cached_content.exists() {
-            #[cfg(debug_assertions)]
-            eprintln!("[CACHE] get_extracted_tarball_by_url: cache miss - meta or content dir not found");
+            debug!("get_extracted_tarball_by_url: cache miss - meta or content dir not found");
            return None;
        }

        let meta: CacheMetadata =
            serde_json::from_str(&fs::read_to_string(&meta_path).ok()?).ok()?;

-        #[cfg(debug_assertions)]
-        eprintln!("[CACHE] get_extracted_tarball_by_url: cached hash={}, name={}", meta.hash, meta.name);
+        debug!(
+            "get_extracted_tarball_by_url: cached hash={}, name={}",
+            meta.hash, meta.name
+        );

        let store_path = self.make_store_path(&meta.hash, &meta.name);
        if store_path.exists() {
-            #[cfg(debug_assertions)]
-            eprintln!("[CACHE] get_extracted_tarball_by_url: HIT - returning store path and hash");
+            debug!("get_extracted_tarball_by_url: HIT - returning store path and hash");
            Some((store_path, meta.hash))
        } else {
-            #[cfg(debug_assertions)]
-            eprintln!("[CACHE] get_extracted_tarball_by_url: store path doesn't exist");
+            debug!("get_extracted_tarball_by_url: store path doesn't exist");
            None
        }
    }
@@ -314,15 +317,17 @@ impl FetcherCache {
        &self,
        url: &str,
        hash: &str,
-        extracted_path: &PathBuf,
+        extracted_path: &Path,
        name: &str,
    ) -> Result<PathBuf, CacheError> {
        let cache_dir = self.tarball_cache_dir();
        let key = Self::hash_key(url);
        let cache_entry_dir = cache_dir.join(&key);

-        #[cfg(debug_assertions)]
-        eprintln!("[CACHE] put_tarball_from_extracted: url={}, hash={}, name={}", url, hash, name);
+        debug!(
+            "put_tarball_from_extracted: url={}, hash={}, name={}",
+            url, hash, name
+        );

        fs::create_dir_all(&cache_entry_dir)?;

@@ -339,16 +344,16 @@ impl FetcherCache {
        fs::write(cache_entry_dir.join(".meta"), serde_json::to_string(&meta)?)?;

        let store_path = self.make_store_path(hash, name);
-        #[cfg(debug_assertions)]
-        eprintln!("[CACHE] put_tarball_from_extracted: store_path={}", store_path.display());
+        debug!(
+            "put_tarball_from_extracted: store_path={}",
+            store_path.display()
+        );
        if !store_path.exists() {
            fs::create_dir_all(store_path.parent().unwrap_or(&store_path))?;
            copy_dir_recursive(extracted_path, &store_path)?;
-            #[cfg(debug_assertions)]
-            eprintln!("[CACHE] put_tarball_from_extracted: copied to store");
+            debug!("put_tarball_from_extracted: copied to store");
        } else {
-            #[cfg(debug_assertions)]
-            eprintln!("[CACHE] put_tarball_from_extracted: store path already exists");
+            debug!("put_tarball_from_extracted: store path already exists");
        }

        Ok(store_path)
@@ -372,7 +377,7 @@ impl FetcherCache {
    }
 }

-fn copy_dir_recursive(src: &PathBuf, dst: &PathBuf) -> Result<(), std::io::Error> {
+fn copy_dir_recursive(src: &Path, dst: &Path) -> Result<(), std::io::Error> {
    fs::create_dir_all(dst)?;

    for entry in fs::read_dir(src)? {
--- a/nix-js/src/fetcher/git.rs
+++ b/nix-js/src/fetcher/git.rs
@@ -5,6 +5,7 @@ use std::process::Command;
 use super::FetchGitResult;
 use super::cache::FetcherCache;

+#[allow(clippy::too_many_arguments)]
 pub fn fetch_git(
    cache: &FetcherCache,
    url: &str,
@@ -166,8 +167,8 @@ fn checkout_rev(
            .output()?;

        if !output.status.success() {
-            eprintln!(
-                "Warning: failed to initialize submodules: {}",
+            tracing::warn!(
+                "failed to initialize submodules: {}",
                String::from_utf8_lossy(&output.stderr)
            );
        }
--- a/nix-js/src/fetcher/nar.rs
+++ b/nix-js/src/fetcher/nar.rs
@@ -1,127 +0,0 @@
-use sha2::{Digest, Sha256};
-use std::fs;
-use std::io::{self, Write};
-use std::path::Path;
-
-pub fn compute_nar_hash(path: &Path) -> Result<String, io::Error> {
-    let mut hasher = Sha256::new();
-    dump_path(&mut hasher, path)?;
-    Ok(hex::encode(hasher.finalize()))
-}
-
-fn dump_path<W: Write>(sink: &mut W, path: &Path) -> io::Result<()> {
-    write_string(sink, "nix-archive-1")?;
-    write_string(sink, "(")?;
-    dump_entry(sink, path)?;
-    write_string(sink, ")")?;
-    Ok(())
-}
-
-fn dump_entry<W: Write>(sink: &mut W, path: &Path) -> io::Result<()> {
-    let metadata = fs::symlink_metadata(path)?;
-
-    if metadata.is_symlink() {
-        let target = fs::read_link(path)?;
-        write_string(sink, "type")?;
-        write_string(sink, "symlink")?;
-        write_string(sink, "target")?;
-        write_string(sink, &target.to_string_lossy())?;
-    } else if metadata.is_file() {
-        write_string(sink, "type")?;
-        write_string(sink, "regular")?;
-
-        #[cfg(unix)]
-        {
-            use std::os::unix::fs::PermissionsExt;
-            if metadata.permissions().mode() & 0o111 != 0 {
-                write_string(sink, "executable")?;
-                write_string(sink, "")?;
-            }
-        }
-
-        let contents = fs::read(path)?;
-        write_string(sink, "contents")?;
-        write_contents(sink, &contents)?;
-    } else if metadata.is_dir() {
-        write_string(sink, "type")?;
-        write_string(sink, "directory")?;
-
-        let mut entries: Vec<_> = fs::read_dir(path)?
-            .filter_map(|e| e.ok())
-            .map(|e| e.file_name().to_string_lossy().to_string())
-            .collect();
-        entries.sort();
-
-        for name in entries {
-            write_string(sink, "entry")?;
-            write_string(sink, "(")?;
-            write_string(sink, "name")?;
-            write_string(sink, &name)?;
-            write_string(sink, "node")?;
-            write_string(sink, "(")?;
-            dump_entry(sink, &path.join(&name))?;
-            write_string(sink, ")")?;
-            write_string(sink, ")")?;
-        }
-    }
-
-    Ok(())
-}
-
-fn write_string<W: Write>(sink: &mut W, s: &str) -> io::Result<()> {
-    let bytes = s.as_bytes();
-    let len = bytes.len() as u64;
-
-    sink.write_all(&len.to_le_bytes())?;
-    sink.write_all(bytes)?;
-
-    let padding = (8 - (len % 8)) % 8;
-    for _ in 0..padding {
-        sink.write_all(&[0])?;
-    }
-
-    Ok(())
-}
-
-fn write_contents<W: Write>(sink: &mut W, contents: &[u8]) -> io::Result<()> {
-    let len = contents.len() as u64;
-
-    sink.write_all(&len.to_le_bytes())?;
-    sink.write_all(contents)?;
-
-    let padding = (8 - (len % 8)) % 8;
-    for _ in 0..padding {
-        sink.write_all(&[0])?;
-    }
-
-    Ok(())
-}
-
-#[cfg(test)]
-#[allow(clippy::unwrap_used)]
-mod tests {
-    use super::*;
-    use tempfile::TempDir;
-
-    #[test]
-    fn test_simple_file() {
-        let temp = TempDir::new().unwrap();
-        let file_path = temp.path().join("test.txt");
-        fs::write(&file_path, "hello").unwrap();
-
-        let hash = compute_nar_hash(&file_path).unwrap();
-        assert!(!hash.is_empty());
-        assert_eq!(hash.len(), 64);
-    }
-
-    #[test]
-    fn test_directory() {
-        let temp = TempDir::new().unwrap();
-        fs::write(temp.path().join("a.txt"), "aaa").unwrap();
-        fs::write(temp.path().join("b.txt"), "bbb").unwrap();
-
-        let hash = compute_nar_hash(temp.path()).unwrap();
-        assert!(!hash.is_empty());
-        assert_eq!(hash.len(), 64);
-    }
-}
--- a/nix-js/src/ir.rs
+++ b/nix-js/src/ir.rs
@@ -353,6 +353,7 @@ pub struct Assert {
    pub assertion: ExprId,
    /// The expression to return if the assertion is true.
    pub expr: ExprId,
+    pub assertion_raw: String,
 }

 /// Represents the concatenation of multiple string expressions.
--- a/nix-js/src/ir/downgrade.rs
+++ b/nix-js/src/ir/downgrade.rs
@@ -3,8 +3,8 @@

 use rnix::ast::{self, Expr, HasEntry};

-use crate::error::{Error, Result};
 use super::*;
+use crate::error::{Error, Result};

 pub trait Downgrade<Ctx: DowngradeContext> {
    fn downgrade(self, ctx: &mut Ctx) -> Result<ExprId>;
@@ -40,9 +40,18 @@ impl<Ctx: DowngradeContext> Downgrade<Ctx> for Expr {

 impl<Ctx: DowngradeContext> Downgrade<Ctx> for ast::Assert {
    fn downgrade(self, ctx: &mut Ctx) -> Result<ExprId> {
-        let assertion = self.condition().unwrap().downgrade(ctx)?;
+        let assertion = self.condition().unwrap();
+        let assertion_raw = assertion.to_string();
+        let assertion = assertion.downgrade(ctx)?;
        let expr = self.body().unwrap().downgrade(ctx)?;
-        Ok(ctx.new_expr(Assert { assertion, expr }.to_ir()))
+        Ok(ctx.new_expr(
+            Assert {
+                assertion,
+                expr,
+                assertion_raw,
+            }
+            .to_ir(),
+        ))
    }
 }

--- a/nix-js/src/lib.rs
+++ b/nix-js/src/lib.rs
@@ -1,13 +1,16 @@
 #![warn(clippy::unwrap_used)]

-mod codegen;
 pub mod context;
 pub mod error;
+pub mod value;
+
+mod codegen;
 mod fetcher;
 mod ir;
 mod nix_hash;
+mod nar;
 mod runtime;
-pub mod value;
+mod store;

 #[global_allocator]
 static GLOBAL: mimalloc::MiMalloc = mimalloc::MiMalloc;
--- a/nix-js/src/nar.rs
+++ b/nix-js/src/nar.rs
@@ -0,0 +1,63 @@
+use nix_nar::Encoder;
+use sha2::{Digest, Sha256};
+use std::io::Read;
+use std::path::Path;
+
+use crate::error::{Error, Result};
+
+pub fn compute_nar_hash(path: &Path) -> Result<String> {
+    let mut hasher = Sha256::new();
+    std::io::copy(
+        &mut Encoder::new(path).map_err(|err| Error::internal(err.to_string()))?,
+        &mut hasher,
+    )
+    .map_err(|err| Error::internal(err.to_string()))?;
+    Ok(hex::encode(hasher.finalize()))
+}
+
+pub fn pack_nar(path: &Path) -> Result<Vec<u8>> {
+    let mut buffer = Vec::new();
+    Encoder::new(path)
+        .map_err(|err| Error::internal(err.to_string()))?
+        .read_to_end(&mut buffer)
+        .map_err(|err| Error::internal(err.to_string()))?;
+    Ok(buffer)
+}
+
+#[cfg(test)]
+#[allow(clippy::unwrap_used)]
+mod tests {
+    use super::*;
+    use std::fs;
+    use tempfile::TempDir;
+
+    #[test]
+    fn test_simple_file() {
+        let temp = TempDir::new().unwrap();
+        let file_path = temp.path().join("test.txt");
+        fs::write(&file_path, "hello").unwrap();
+
+        let hash = compute_nar_hash(&file_path).unwrap();
+        assert_eq!(
+            hash,
+            "0a430879c266f8b57f4092a0f935cf3facd48bbccde5760d4748ca405171e969"
+        );
+        assert!(!hash.is_empty());
+        assert_eq!(hash.len(), 64);
+    }
+
+    #[test]
+    fn test_directory() {
+        let temp = TempDir::new().unwrap();
+        fs::write(temp.path().join("a.txt"), "aaa").unwrap();
+        fs::write(temp.path().join("b.txt"), "bbb").unwrap();
+
+        let hash = compute_nar_hash(temp.path()).unwrap();
+        assert_eq!(
+            hash,
+            "0036c14209749bc9b9631e2077b108b701c322ab53853cd26f2746268a86fc0f"
+        );
+        assert!(!hash.is_empty());
+        assert_eq!(hash.len(), 64);
+    }
+}
--- a/nix-js/src/nix_hash.rs
+++ b/nix-js/src/nix_hash.rs
@@ -1,7 +1,6 @@
 use sha2::{Digest, Sha256};

 const NIX_BASE32_CHARS: &[u8; 32] = b"0123456789abcdfghijklmnpqrsvwxyz";
-const STORE_DIR: &str = "/nix/store";

 pub fn sha256_hex(data: &str) -> String {
    let mut hasher = Sha256::new();
@@ -42,8 +41,8 @@ pub fn nix_base32_encode(bytes: &[u8]) -> String {
    result
 }

-pub fn make_store_path(ty: &str, hash_hex: &str, name: &str) -> String {
-    let s = format!("{}:sha256:{}:{}:{}", ty, hash_hex, STORE_DIR, name);
+pub fn make_store_path(store_dir: &str, ty: &str, hash_hex: &str, name: &str) -> String {
+    let s = format!("{}:sha256:{}:{}:{}", ty, hash_hex, store_dir, name);

    let mut hasher = Sha256::new();
    hasher.update(s.as_bytes());
@@ -52,7 +51,7 @@ pub fn make_store_path(ty: &str, hash_hex: &str, name: &str) -> String {
    let compressed = compress_hash(&hash, 20);
    let encoded = nix_base32_encode(&compressed);

-    format!("{}/{}-{}", STORE_DIR, encoded, name)
+    format!("{}/{}-{}", store_dir, encoded, name)
 }

 pub fn output_path_name(drv_name: &str, output_name: &str) -> String {
@@ -111,7 +110,7 @@ mod tests {

    #[test]
    fn test_make_store_path() {
-        let path = make_store_path("output:out", "abc123", "hello");
+        let path = make_store_path("/nix/store", "output:out", "abc123", "hello");
        assert!(path.starts_with("/nix/store/"));
        assert!(path.ends_with("-hello"));

--- a/nix-js/src/runtime.rs
+++ b/nix-js/src/runtime.rs
@@ -1,7 +1,6 @@
 use std::borrow::Cow;
 use std::marker::PhantomData;
-use std::ops::DerefMut;
-use std::path::{Component, PathBuf};
+use std::path::{Component, Path, PathBuf};
 use std::sync::Once;

 use deno_core::{Extension, ExtensionFileSource, JsRuntime, OpState, RuntimeOptions, v8};
@@ -14,25 +13,27 @@ type ScopeRef<'p, 's> = v8::PinnedRef<'p, v8::HandleScope<'s>>;
 type LocalValue<'a> = v8::Local<'a, v8::Value>;
 type LocalSymbol<'a> = v8::Local<'a, v8::Symbol>;

-pub(crate) trait RuntimeCtx: 'static {
-    fn get_current_dir(&self) -> PathBuf;
-    fn push_path_stack(&mut self, path: PathBuf) -> impl DerefMut<Target = Self>;
+pub(crate) trait RuntimeContext: 'static {
+    fn get_current_dir(&self) -> &Path;
+    fn set_current_file(&mut self, path: PathBuf);
    fn compile_code(&mut self, code: &str) -> Result<String>;
 }

-fn runtime_extension<Ctx: RuntimeCtx>() -> Extension {
+fn runtime_extension<Ctx: RuntimeContext>() -> Extension {
    const ESM: &[ExtensionFileSource] =
        &deno_core::include_js_files!(nix_runtime dir "runtime-ts/dist", "runtime.js");
    let mut ops = vec![
        op_import::<Ctx>(),
        op_read_file(),
        op_path_exists(),
-        op_resolve_path::<Ctx>(),
+        op_resolve_path(),
        op_sha256_hex(),
        op_make_store_path(),
        op_output_path_name(),
        op_make_fixed_output_path(),
        op_add_path(),
+        op_store_path(),
+        op_to_file(),
    ];
    ops.extend(crate::fetcher::register_ops());

@@ -75,7 +76,7 @@ pub(crate) use private::NixError;

 #[deno_core::op2]
 #[string]
-fn op_import<Ctx: RuntimeCtx>(
+fn op_import<Ctx: RuntimeContext>(
    state: &mut OpState,
    #[string] path: String,
 ) -> std::result::Result<String, NixError> {
@@ -93,10 +94,8 @@ fn op_import<Ctx: RuntimeCtx>(
    let content = std::fs::read_to_string(&absolute_path)
        .map_err(|e| format!("Failed to read {}: {}", absolute_path.display(), e))?;

-    #[cfg(debug_assertions)]
-    eprintln!("[DEBUG] compiling file: {}", absolute_path.display());
-    let mut guard = ctx.push_path_stack(absolute_path);
-    let ctx = guard.deref_mut();
+    tracing::debug!("compiling file: {}", absolute_path.display());
+    ctx.set_current_file(absolute_path);

    Ok(ctx.compile_code(&content).map_err(|err| err.to_string())?)
 }
@@ -114,19 +113,17 @@ fn op_path_exists(#[string] path: String) -> bool {

 #[deno_core::op2]
 #[string]
-fn op_resolve_path<Ctx: RuntimeCtx>(
-    state: &mut OpState,
+fn op_resolve_path(
+    #[string] current_dir: String,
    #[string] path: String,
 ) -> std::result::Result<String, NixError> {
-    let ctx = state.borrow::<Ctx>();
-
    // If already absolute, return as-is
    if path.starts_with('/') {
        return Ok(path);
    }

    // Resolve relative path against current file directory (or CWD)
-    let current_dir = ctx.get_current_dir().join(&path);
+    let current_dir = PathBuf::from(current_dir).join(&path);
    let mut normalized = PathBuf::new();
    for component in current_dir.components() {
        match component {
@@ -151,11 +148,17 @@ fn op_sha256_hex(#[string] data: String) -> String {
 #[deno_core::op2]
 #[string]
 fn op_make_store_path(
+    state: &mut OpState,
    #[string] ty: String,
    #[string] hash_hex: String,
    #[string] name: String,
 ) -> String {
-    crate::nix_hash::make_store_path(&ty, &hash_hex, &name)
+    use crate::store::StoreBackend;
+    use std::sync::Arc;
+
+    let store = state.borrow::<Arc<StoreBackend>>();
+    let store_dir = store.as_store().get_store_dir();
+    crate::nix_hash::make_store_path(store_dir, &ty, &hash_hex, &name)
 }

 #[deno_core::op2]
@@ -167,15 +170,21 @@ fn op_output_path_name(#[string] drv_name: String, #[string] output_name: String
 #[deno_core::op2]
 #[string]
 fn op_make_fixed_output_path(
+    state: &mut OpState,
    #[string] hash_algo: String,
    #[string] hash: String,
    #[string] hash_mode: String,
    #[string] name: String,
 ) -> String {
+    use crate::store::StoreBackend;
    use sha2::{Digest, Sha256};
+    use std::sync::Arc;
+
+    let store = state.borrow::<Arc<StoreBackend>>();
+    let store_dir = store.as_store().get_store_dir();

    if hash_algo == "sha256" && hash_mode == "recursive" {
-        crate::nix_hash::make_store_path("source", &hash, &name)
+        crate::nix_hash::make_store_path(store_dir, "source", &hash, &name)
    } else {
        let prefix = if hash_mode == "recursive" { "r:" } else { "" };
        let inner_input = format!("fixed:out:{}{}:{}:", prefix, hash_algo, hash);
@@ -183,21 +192,24 @@ fn op_make_fixed_output_path(
        hasher.update(inner_input.as_bytes());
        let inner_hash = hex::encode(hasher.finalize());

-        crate::nix_hash::make_store_path("output:out", &inner_hash, &name)
+        crate::nix_hash::make_store_path(store_dir, "output:out", &inner_hash, &name)
    }
 }

 #[deno_core::op2]
 #[string]
 fn op_add_path(
+    state: &mut OpState,
    #[string] path: String,
    #[string] name: Option<String>,
    recursive: bool,
    #[string] sha256: Option<String>,
 ) -> std::result::Result<String, NixError> {
+    use crate::store::StoreBackend;
    use sha2::{Digest, Sha256};
    use std::fs;
    use std::path::Path;
+    use std::sync::Arc;

    let path_obj = Path::new(&path);

@@ -229,16 +241,18 @@ fn op_add_path(
        hex::encode(hasher.finalize())
    };

-    if let Some(expected_hash) = sha256 {
-        if computed_hash != expected_hash {
-            return Err(NixError::from(format!(
-                "hash mismatch for path '{}': expected {}, got {}",
-                path, expected_hash, computed_hash
-            )));
-        }
+    if let Some(expected_hash) = sha256
+        && computed_hash != expected_hash
+    {
+        return Err(NixError::from(format!(
+            "hash mismatch for path '{}': expected {}, got {}",
+            path, expected_hash, computed_hash
+        )));
    }

-    let store_path = crate::nix_hash::make_store_path("source", &computed_hash, &computed_name);
+    let store = state.borrow::<Arc<StoreBackend>>();
+    let store_dir = store.as_store().get_store_dir();
+    let store_path = crate::nix_hash::make_store_path(store_dir, "source", &computed_hash, &computed_name);

    Ok(store_path)
 }
@@ -248,8 +262,8 @@ fn compute_nar_hash(path: &std::path::Path) -> std::result::Result<String, NixEr
    use std::fs;

    if path.is_file() {
-        let contents = fs::read(path)
-            .map_err(|e| NixError::from(format!("failed to read file: {}", e)))?;
+        let contents =
+            fs::read(path).map_err(|e| NixError::from(format!("failed to read file: {}", e)))?;
        let mut hasher = Sha256::new();
        hasher.update(&contents);
        Ok(hex::encode(hasher.finalize()))
@@ -278,8 +292,49 @@ fn compute_nar_hash(path: &std::path::Path) -> std::result::Result<String, NixEr
    }
 }

+#[deno_core::op2]
+#[string]
+fn op_store_path(
+    state: &mut OpState,
+    #[string] path: String,
+) -> std::result::Result<String, NixError> {
+    use crate::store::{validate_store_path, StoreBackend};
+    use std::sync::Arc;

-pub(crate) struct Runtime<Ctx: RuntimeCtx> {
+    let store = state.borrow::<Arc<StoreBackend>>();
+    let store_dir = store.as_store().get_store_dir();
+
+    validate_store_path(store_dir, &path).map_err(|e| NixError::from(e.to_string()))?;
+
+    store
+        .as_store()
+        .ensure_path(&path)
+        .map_err(|e| NixError::from(e.to_string()))?;
+
+    Ok(path)
+}
+
+#[deno_core::op2]
+#[string]
+fn op_to_file(
+    state: &mut OpState,
+    #[string] name: String,
+    #[string] contents: String,
+    #[serde] references: Vec<String>,
+) -> std::result::Result<String, NixError> {
+    use crate::store::StoreBackend;
+    use std::sync::Arc;
+
+    let store = state.borrow::<Arc<StoreBackend>>();
+    let store_path = store
+        .as_store()
+        .add_text_to_store(&name, &contents, references)
+        .map_err(|e| NixError::from(format!("builtins.toFile failed: {}", e)))?;
+
+    Ok(store_path)
+}
+
+pub(crate) struct Runtime<Ctx: RuntimeContext> {
    js_runtime: JsRuntime,
    is_thunk_symbol: v8::Global<v8::Symbol>,
    primop_metadata_symbol: v8::Global<v8::Symbol>,
@@ -288,7 +343,7 @@ pub(crate) struct Runtime<Ctx: RuntimeCtx> {
    _marker: PhantomData<Ctx>,
 }

-impl<Ctx: RuntimeCtx> Runtime<Ctx> {
+impl<Ctx: RuntimeContext> Runtime<Ctx> {
    pub(crate) fn new() -> Result<Self> {
        // Initialize V8 once
        static INIT: Once = Once::new();
@@ -319,6 +374,10 @@ impl<Ctx: RuntimeCtx> Runtime<Ctx> {
        })
    }

+    pub(crate) fn op_state(&mut self) -> std::rc::Rc<std::cell::RefCell<OpState>> {
+        self.js_runtime.op_state()
+    }
+
    pub(crate) fn eval(&mut self, script: String, ctx: Ctx) -> Result<Value> {
        self.js_runtime.op_state().borrow_mut().put(ctx);

@@ -345,7 +404,8 @@ impl<Ctx: RuntimeCtx> Runtime<Ctx> {
        ))
    }

-    /// get (IS_THUNK, PRIMOP_METADATA, HAS_CONTEXT)
+    /// get (IS_THUNK, PRIMOP_METADATA, HAS_CONTEXT, IS_PATH)
+    #[allow(clippy::type_complexity)]
    fn get_symbols(
        scope: &ScopeRef,
    ) -> Result<(
@@ -365,55 +425,24 @@ impl<Ctx: RuntimeCtx> Runtime<Ctx> {
                Error::internal("failed to convert global Nix Value to object".into())
            })?;

-        let is_thunk_sym_key = v8::String::new(scope, "IS_THUNK")
-            .ok_or_else(|| Error::internal("failed to create V8 String".into()))?;
-        let is_thunk_sym = nix_obj
-            .get(scope, is_thunk_sym_key.into())
-            .ok_or_else(|| Error::internal("failed to get IS_THUNK Symbol".into()))?;
-        let is_thunk = is_thunk_sym.try_cast::<v8::Symbol>().map_err(|err| {
-            Error::internal(format!(
-                "failed to convert IS_THUNK Value to Symbol ({err})"
-            ))
-        })?;
-        let is_thunk = v8::Global::new(scope, is_thunk);
-
-        let primop_metadata_sym_key = v8::String::new(scope, "PRIMOP_METADATA")
-            .ok_or_else(|| Error::internal("failed to create V8 String".into()))?;
-        let primop_metadata_sym = nix_obj
-            .get(scope, primop_metadata_sym_key.into())
-            .ok_or_else(|| Error::internal("failed to get PRIMOP_METADATA Symbol".into()))?;
-        let primop_metadata = primop_metadata_sym
-            .try_cast::<v8::Symbol>()
-            .map_err(|err| {
+        let get_symbol = |symbol| {
+            let key = v8::String::new(scope, symbol)
+                .ok_or_else(|| Error::internal("failed to create V8 String".into()))?;
+            let val = nix_obj
+                .get(scope, key.into())
+                .ok_or_else(|| Error::internal(format!("failed to get {symbol} Symbol")))?;
+            let sym = val.try_cast::<v8::Symbol>().map_err(|err| {
                Error::internal(format!(
-                    "failed to convert PRIMOP_METADATA Value to Symbol ({err})"
+                    "failed to convert {symbol} Value to Symbol ({err})"
                ))
            })?;
-        let primop_metadata = v8::Global::new(scope, primop_metadata);
+            Ok(v8::Global::new(scope, sym))
+        };

-        let has_context_sym_key = v8::String::new(scope, "HAS_CONTEXT")
-            .ok_or_else(|| Error::internal("failed to create V8 String".into()))?;
-        let has_context_sym = nix_obj
-            .get(scope, has_context_sym_key.into())
-            .ok_or_else(|| Error::internal("failed to get HAS_CONTEXT Symbol".into()))?;
-        let has_context = has_context_sym.try_cast::<v8::Symbol>().map_err(|err| {
-            Error::internal(format!(
-                "failed to convert HAS_CONTEXT Value to Symbol ({err})"
-            ))
-        })?;
-        let has_context = v8::Global::new(scope, has_context);
-
-        let is_path_sym_key = v8::String::new(scope, "IS_PATH")
-            .ok_or_else(|| Error::internal("failed to create V8 String".into()))?;
-        let is_path_sym = nix_obj
-            .get(scope, is_path_sym_key.into())
-            .ok_or_else(|| Error::internal("failed to get IS_PATH Symbol".into()))?;
-        let is_path = is_path_sym.try_cast::<v8::Symbol>().map_err(|err| {
-            Error::internal(format!(
-                "failed to convert IS_PATH Value to Symbol ({err})"
-            ))
-        })?;
-        let is_path = v8::Global::new(scope, is_path);
+        let is_thunk = get_symbol("IS_THUNK")?;
+        let primop_metadata = get_symbol("PRIMOP_METADATA")?;
+        let has_context = get_symbol("HAS_CONTEXT")?;
+        let is_path = get_symbol("IS_PATH")?;

        Ok((is_thunk, primop_metadata, has_context, is_path))
    }
@@ -616,14 +645,9 @@ mod test {
    #[test]
    fn to_value_working() {
        let mut ctx = Context::new().unwrap();
+        const EXPR: &str = "({ test: [1., 9223372036854775807n, true, false, 'hello world!'] })";
        assert_eq!(
-            ctx.eval_js(
-                "({
-                  test: [1., 9223372036854775807n, true, false, 'hello world!']
-                })"
-                .into(),
-            )
-            .unwrap(),
+            ctx.eval_js(EXPR.into()).unwrap(),
            Value::AttrSet(AttrSet::new(std::collections::BTreeMap::from([(
                Symbol::from("test"),
                Value::List(List::new(vec![
--- a/nix-js/src/store.rs
+++ b/nix-js/src/store.rs
@@ -0,0 +1,110 @@
+mod config;
+mod error;
+mod validation;
+
+use std::path::Path;
+
+pub use config::{StoreConfig, StoreMode};
+pub use validation::validate_store_path;
+
+use crate::error::Result;
+
+pub trait Store: Send + Sync {
+    fn get_store_dir(&self) -> &str;
+
+    fn is_valid_path(&self, path: &str) -> Result<bool>;
+
+    fn ensure_path(&self, path: &str) -> Result<()>;
+
+    fn add_to_store(
+        &self,
+        name: &str,
+        content: &[u8],
+        recursive: bool,
+        references: Vec<String>,
+    ) -> Result<String>;
+
+    fn add_text_to_store(
+        &self,
+        name: &str,
+        content: &str,
+        references: Vec<String>,
+    ) -> Result<String>;
+
+    fn put_directory(&self, name: &str, path: &Path) -> Result<String>;
+
+    fn make_fixed_output_path(
+        &self,
+        hash_algo: &str,
+        hash: &str,
+        hash_mode: &str,
+        name: &str,
+    ) -> Result<String>;
+}
+
+pub enum StoreBackend {
+    Simulated(SimulatedStore),
+    #[cfg(feature = "daemon")]
+    Daemon(DaemonStore),
+}
+
+impl StoreBackend {
+    pub fn new(config: StoreConfig) -> Result<Self> {
+        match config.mode {
+            #[cfg(feature = "daemon")]
+            StoreMode::Daemon => {
+                let daemon = DaemonStore::connect(&config.daemon_socket)?;
+                Ok(StoreBackend::Daemon(daemon))
+            }
+            #[cfg(not(feature = "daemon"))]
+            StoreMode::Daemon => {
+                tracing::warn!("Daemon mode not available (nix-js not compiled with 'daemon' feature), falling back to simulated store");
+                let simulated = SimulatedStore::new()?;
+                Ok(StoreBackend::Simulated(simulated))
+            }
+            StoreMode::Simulated => {
+                let simulated = SimulatedStore::new()?;
+                Ok(StoreBackend::Simulated(simulated))
+            }
+            #[cfg(feature = "daemon")]
+            StoreMode::Auto => match DaemonStore::connect(&config.daemon_socket) {
+                Ok(daemon) => {
+                    tracing::debug!(
+                        "Using nix-daemon at {}",
+                        config.daemon_socket.display()
+                    );
+                    Ok(StoreBackend::Daemon(daemon))
+                }
+                Err(e) => {
+                    tracing::warn!(
+                        "Daemon unavailable ({}), using simulated store",
+                        e
+                    );
+                    let simulated = SimulatedStore::new()?;
+                    Ok(StoreBackend::Simulated(simulated))
+                }
+            },
+            #[cfg(not(feature = "daemon"))]
+            StoreMode::Auto => {
+                let simulated = SimulatedStore::new()?;
+                Ok(StoreBackend::Simulated(simulated))
+            }
+        }
+    }
+
+    pub fn as_store(&self) -> &dyn Store {
+        match self {
+            StoreBackend::Simulated(s) => s,
+            #[cfg(feature = "daemon")]
+            StoreBackend::Daemon(d) => d,
+        }
+    }
+}
+
+mod simulated;
+pub use simulated::SimulatedStore;
+
+#[cfg(feature = "daemon")]
+mod daemon;
+#[cfg(feature = "daemon")]
+pub use daemon::DaemonStore;
--- a/nix-js/src/store/config.rs
+++ b/nix-js/src/store/config.rs
@@ -0,0 +1,50 @@
+use std::path::PathBuf;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum StoreMode {
+    Daemon,
+    Simulated,
+    Auto,
+}
+
+#[derive(Debug, Clone)]
+pub struct StoreConfig {
+    pub mode: StoreMode,
+    pub daemon_socket: PathBuf,
+}
+
+impl StoreConfig {
+    pub fn from_env() -> Self {
+        let mode = match std::env::var("NIX_JS_STORE_MODE")
+            .as_deref()
+            .map(|s| s.to_lowercase())
+            .as_deref()
+        {
+            Ok("daemon") => StoreMode::Daemon,
+            Ok("simulated") => StoreMode::Simulated,
+            Ok("auto") | Err(_) => StoreMode::Auto,
+            Ok(other) => {
+                tracing::warn!(
+                    "Invalid NIX_JS_STORE_MODE '{}', using 'auto'",
+                    other
+                );
+                StoreMode::Auto
+            }
+        };
+
+        let daemon_socket = std::env::var("NIX_DAEMON_SOCKET")
+            .map(PathBuf::from)
+            .unwrap_or_else(|_| PathBuf::from("/nix/var/nix/daemon-socket/socket"));
+
+        Self {
+            mode,
+            daemon_socket,
+        }
+    }
+}
+
+impl Default for StoreConfig {
+    fn default() -> Self {
+        Self::from_env()
+    }
+}
--- a/nix-js/src/store/daemon.rs
+++ b/nix-js/src/store/daemon.rs
@@ -0,0 +1,166 @@
+use std::path::Path;
+use std::sync::Arc;
+
+use nix_daemon::{Progress as _, Store as _, nix};
+use tokio::net::UnixStream;
+use tokio::sync::Mutex;
+
+use crate::error::{Error, Result};
+use crate::nar::pack_nar;
+
+use super::Store;
+
+pub struct DaemonStore {
+    runtime: tokio::runtime::Runtime,
+    store: Arc<Mutex<nix::DaemonStore<UnixStream>>>,
+}
+
+impl DaemonStore {
+    pub fn connect(socket_path: &Path) -> Result<Self> {
+        let runtime = tokio::runtime::Runtime::new()
+            .map_err(|e| Error::internal(format!("Failed to create tokio runtime: {}", e)))?;
+
+        let socket_str = socket_path
+            .to_str()
+            .ok_or_else(|| Error::internal("Invalid socket path: not UTF-8".to_string()))?;
+
+        let store = runtime.block_on(async {
+            nix_daemon::nix::DaemonStore::builder()
+                .connect_unix(socket_str)
+                .await
+                .map_err(|e| {
+                    Error::internal(format!(
+                        "Failed to connect to nix-daemon at {}: {}",
+                        socket_str, e
+                    ))
+                })
+        })?;
+
+        Ok(Self {
+            runtime,
+            store: Arc::new(Mutex::new(store)),
+        })
+    }
+
+    fn block_on<F>(&self, future: F) -> F::Output
+    where
+        F: std::future::Future,
+    {
+        self.runtime.block_on(future)
+    }
+}
+
+impl Store for DaemonStore {
+    fn get_store_dir(&self) -> &str {
+        "/nix/store"
+    }
+
+    fn is_valid_path(&self, path: &str) -> Result<bool> {
+        self.block_on(async {
+            let mut store = self.store.lock().await;
+            store
+                .is_valid_path(path)
+                .result()
+                .await
+                .map_err(|e| Error::internal(format!("Daemon error in is_valid_path: {}", e)))
+        })
+    }
+
+    fn ensure_path(&self, path: &str) -> Result<()> {
+        self.block_on(async {
+            let mut store = self.store.lock().await;
+            store.ensure_path(path).result().await.map_err(|e| {
+                Error::eval_error(
+                    format!(
+                        "builtins.storePath: path '{}' is not valid in nix store: {}",
+                        path, e
+                    ),
+                    None,
+                )
+            })
+        })
+    }
+
+    fn add_to_store(
+        &self,
+        name: &str,
+        content: &[u8],
+        recursive: bool,
+        references: Vec<String>,
+    ) -> Result<String> {
+        let temp_dir = tempfile::tempdir()
+            .map_err(|e| Error::internal(format!("Failed to create temp dir: {}", e)))?;
+        let content_path = temp_dir.path().join(name);
+        std::fs::write(&content_path, content)
+            .map_err(|e| Error::internal(format!("Failed to write content: {}", e)))?;
+
+        let cam_str = if recursive {
+            "fixed:r:sha256"
+        } else {
+            "fixed:sha256"
+        };
+
+        self.block_on(async {
+            let mut store = self.store.lock().await;
+            let (store_path, _path_info) = store
+                .add_to_store(
+                    name,
+                    cam_str,
+                    references,
+                    false,
+                    content_path.as_os_str().as_encoded_bytes(),
+                )
+                .result()
+                .await
+                .map_err(|e| Error::internal(format!("Daemon error in add_to_store: {}", e)))?;
+
+            Ok(store_path)
+        })
+    }
+
+    fn add_text_to_store(
+        &self,
+        name: &str,
+        content: &str,
+        references: Vec<String>,
+    ) -> Result<String> {
+        self.block_on(async {
+            let mut store = self.store.lock().await;
+            let (store_path, _) = store
+                .add_to_store(name, "text:sha256", references, false, content.as_bytes())
+                .result()
+                .await
+                .map_err(|e| {
+                    Error::internal(format!("Daemon error in add_text_to_store: {}", e))
+                })?;
+
+            Ok(store_path)
+        })
+    }
+
+    fn put_directory(&self, name: &str, path: &Path) -> Result<String> {
+        self.block_on(async {
+            let mut store = self.store.lock().await;
+            let (store_path, _) = store
+                .add_to_store(name, "text:sha256", std::iter::empty::<&str>(), false, pack_nar(path).unwrap().as_slice())
+                .result()
+                .await
+                .map_err(|e| {
+                    Error::internal(format!("Daemon error in add_text_to_store: {}", e))
+                })?;
+
+            Ok(store_path)
+        })
+    }
+
+    fn make_fixed_output_path(
+        &self,
+        _hash_algo: &str,
+        hash: &str,
+        _hash_mode: &str,
+        name: &str,
+    ) -> Result<String> {
+        let short_hash = &hash[..32.min(hash.len())];
+        Ok(format!("/nix/store/{}-{}", short_hash, name))
+    }
+}
--- a/nix-js/src/store/error.rs
+++ b/nix-js/src/store/error.rs
@@ -0,0 +1,32 @@
+use std::fmt;
+
+#[derive(Debug)]
+pub enum StoreError {
+    DaemonConnectionFailed(String),
+    OperationFailed(String),
+    InvalidPath(String),
+    PathNotFound(String),
+    Io(std::io::Error),
+}
+
+impl fmt::Display for StoreError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            StoreError::DaemonConnectionFailed(msg) => {
+                write!(f, "Failed to connect to nix-daemon: {}", msg)
+            }
+            StoreError::OperationFailed(msg) => write!(f, "Store operation failed: {}", msg),
+            StoreError::InvalidPath(msg) => write!(f, "Invalid store path: {}", msg),
+            StoreError::PathNotFound(path) => write!(f, "Path not found in store: {}", path),
+            StoreError::Io(e) => write!(f, "I/O error: {}", e),
+        }
+    }
+}
+
+impl std::error::Error for StoreError {}
+
+impl From<std::io::Error> for StoreError {
+    fn from(e: std::io::Error) -> Self {
+        StoreError::Io(e)
+    }
+}
--- a/nix-js/src/store/simulated.rs
+++ b/nix-js/src/store/simulated.rs
@@ -0,0 +1,100 @@
+use super::Store;
+use crate::error::{Error, Result};
+use crate::fetcher::cache::FetcherCache;
+use std::fs;
+use std::path::Path;
+
+pub struct SimulatedStore {
+    cache: FetcherCache,
+    store_dir: String,
+}
+
+impl SimulatedStore {
+    pub fn new() -> Result<Self> {
+        let cache = FetcherCache::new()
+            .map_err(|e| Error::internal(format!("Failed to create simulated store: {}", e)))?;
+
+        let store_dir = dirs::cache_dir()
+            .unwrap_or_else(|| std::path::PathBuf::from("/tmp"))
+            .join("nix-js")
+            .join("fetchers")
+            .join("store")
+            .to_string_lossy()
+            .to_string();
+
+        Ok(Self { cache, store_dir })
+    }
+
+    pub fn cache(&self) -> &FetcherCache {
+        &self.cache
+    }
+}
+
+impl Store for SimulatedStore {
+    fn get_store_dir(&self) -> &str {
+        &self.store_dir
+    }
+
+    fn is_valid_path(&self, path: &str) -> Result<bool> {
+        Ok(Path::new(path).exists())
+    }
+
+    fn ensure_path(&self, path: &str) -> Result<()> {
+        if !Path::new(path).exists() {
+            return Err(Error::eval_error(
+                format!(
+                    "builtins.storePath: path '{}' does not exist in the simulated store",
+                    path
+                ),
+                None,
+            ));
+        }
+        Ok(())
+    }
+
+    fn add_to_store(
+        &self,
+        name: &str,
+        content: &[u8],
+        _recursive: bool,
+        _references: Vec<String>,
+    ) -> Result<String> {
+        let hash = crate::nix_hash::sha256_hex(&String::from_utf8_lossy(content));
+
+        let store_path = self.cache.make_store_path(&hash, name);
+
+        if !store_path.exists() {
+            fs::create_dir_all(store_path.parent().unwrap_or(&store_path))
+                .map_err(|e| Error::internal(format!("Failed to create store directory: {}", e)))?;
+
+            fs::write(&store_path, content)
+                .map_err(|e| Error::internal(format!("Failed to write to store: {}", e)))?;
+        }
+
+        Ok(store_path.to_string_lossy().to_string())
+    }
+
+    fn add_text_to_store(
+        &self,
+        name: &str,
+        content: &str,
+        references: Vec<String>,
+    ) -> Result<String> {
+        self.add_to_store(name, content.as_bytes(), false, references)
+    }
+
+    fn make_fixed_output_path(
+        &self,
+        _hash_algo: &str,
+        hash: &str,
+        _hash_mode: &str,
+        name: &str,
+    ) -> Result<String> {
+        let store_path = self.cache.make_store_path(hash, name);
+        Ok(store_path.to_string_lossy().to_string())
+    }
+
+    fn put_directory(&self, name: &str, path: &Path) -> Result<String> {
+        todo!()
+    }
+}
--- a/nix-js/src/store/validation.rs
+++ b/nix-js/src/store/validation.rs
@@ -0,0 +1,132 @@
+use crate::error::{Error, Result};
+
+pub fn validate_store_path(store_dir: &str, path: &str) -> Result<()> {
+    if !path.starts_with(store_dir) {
+        return Err(Error::eval_error(
+            format!("path '{}' is not in the Nix store", path),
+            None,
+        ));
+    }
+
+    let relative = path
+        .strip_prefix(store_dir)
+        .and_then(|s| s.strip_prefix('/'))
+        .ok_or_else(|| Error::eval_error(format!("invalid store path format: {}", path), None))?;
+
+    if relative.is_empty() {
+        return Err(Error::eval_error(
+            format!("store path cannot be store directory itself: {}", path),
+            None,
+        ));
+    }
+
+    let parts: Vec<&str> = relative.splitn(2, '-').collect();
+    if parts.len() != 2 {
+        return Err(Error::eval_error(
+            format!("invalid store path format (missing name): {}", path),
+            None,
+        ));
+    }
+
+    let hash = parts[0];
+    let name = parts[1];
+
+    if hash.len() != 32 {
+        return Err(Error::eval_error(
+            format!(
+                "invalid store path hash length (expected 32, got {}): {}",
+                hash.len(),
+                hash
+            ),
+            None,
+        ));
+    }
+
+    for ch in hash.chars() {
+        if !matches!(ch, '0'..='9' | 'a'..='d' | 'f'..='n' | 'p'..='s' | 'v'..='z') {
+            return Err(Error::eval_error(
+                format!("invalid character '{}' in store path hash: {}", ch, hash),
+                None,
+            ));
+        }
+    }
+
+    if name.is_empty() {
+        return Err(Error::eval_error(
+            format!("store path has empty name: {}", path),
+            None,
+        ));
+    }
+
+    if name.starts_with('.') {
+        return Err(Error::eval_error(
+            format!("store path name cannot start with '.': {}", name),
+            None,
+        ));
+    }
+
+    for ch in name.chars() {
+        if !matches!(ch, '0'..='9' | 'a'..='z' | 'A'..='Z' | '+' | '-' | '.' | '_' | '?' | '=') {
+            return Err(Error::eval_error(
+                format!("invalid character '{}' in store path name: {}", ch, name),
+                None,
+            ));
+        }
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_valid_store_paths() {
+        let store_dir = "/nix/store";
+        let valid_paths = vec![
+            "/nix/store/0123456789abcdfghijklmnpqrsvwxyz-hello",
+            "/nix/store/abcdfghijklmnpqrsvwxyz0123456789-hello-1.0",
+            "/nix/store/00000000000000000000000000000000-test_+-.?="
+        ];
+
+        for path in valid_paths {
+            assert!(
+                validate_store_path(store_dir, path).is_ok(),
+                "Expected {} to be valid, got {:?}",
+                path,
+                validate_store_path(store_dir, path)
+            );
+        }
+    }
+
+    #[test]
+    fn test_invalid_store_paths() {
+        let store_dir = "/nix/store";
+        let invalid_paths = vec![
+            ("/tmp/foo", "not in store"),
+            ("/nix/store", "empty relative"),
+            ("/nix/store/tooshort-name", "hash too short"),
+            (
+                "/nix/store/abc123defghijklmnopqrstuvwxyz123-name",
+                "hash too long"
+            ),
+            ("/nix/store/abcd1234abcd1234abcd1234abcd123e-name", "e in hash"),
+            ("/nix/store/abcd1234abcd1234abcd1234abcd123o-name", "o in hash"),
+            ("/nix/store/abcd1234abcd1234abcd1234abcd123u-name", "u in hash"),
+            ("/nix/store/abcd1234abcd1234abcd1234abcd123t-name", "t in hash"),
+            ("/nix/store/abcd1234abcd1234abcd1234abcd1234-.name", "name starts with dot"),
+            ("/nix/store/abcd1234abcd1234abcd1234abcd1234-na/me", "slash in name"),
+            ("/nix/store/abcd1234abcd1234abcd1234abcd1234", "missing name"),
+        ];
+
+        for (path, reason) in invalid_paths {
+            assert!(
+                validate_store_path(store_dir, path).is_err(),
+                "Expected {} to be invalid ({})",
+                path,
+                reason
+            );
+        }
+    }
+}
--- a/nix-js/tests/builtins.rs
+++ b/nix-js/tests/builtins.rs
@@ -150,40 +150,85 @@ fn builtins_concat_lists() {

 #[test]
 fn builtins_compare_versions_basic() {
-    assert_eq!(eval("builtins.compareVersions \"1.0\" \"2.3\""), Value::Int(-1));
-    assert_eq!(eval("builtins.compareVersions \"2.1\" \"2.3\""), Value::Int(-1));
-    assert_eq!(eval("builtins.compareVersions \"2.3\" \"2.3\""), Value::Int(0));
-    assert_eq!(eval("builtins.compareVersions \"2.5\" \"2.3\""), Value::Int(1));
-    assert_eq!(eval("builtins.compareVersions \"3.1\" \"2.3\""), Value::Int(1));
+    assert_eq!(
+        eval("builtins.compareVersions \"1.0\" \"2.3\""),
+        Value::Int(-1)
+    );
+    assert_eq!(
+        eval("builtins.compareVersions \"2.1\" \"2.3\""),
+        Value::Int(-1)
+    );
+    assert_eq!(
+        eval("builtins.compareVersions \"2.3\" \"2.3\""),
+        Value::Int(0)
+    );
+    assert_eq!(
+        eval("builtins.compareVersions \"2.5\" \"2.3\""),
+        Value::Int(1)
+    );
+    assert_eq!(
+        eval("builtins.compareVersions \"3.1\" \"2.3\""),
+        Value::Int(1)
+    );
 }

 #[test]
 fn builtins_compare_versions_components() {
-    assert_eq!(eval("builtins.compareVersions \"2.3.1\" \"2.3\""), Value::Int(1));
-    assert_eq!(eval("builtins.compareVersions \"2.3\" \"2.3.1\""), Value::Int(-1));
+    assert_eq!(
+        eval("builtins.compareVersions \"2.3.1\" \"2.3\""),
+        Value::Int(1)
+    );
+    assert_eq!(
+        eval("builtins.compareVersions \"2.3\" \"2.3.1\""),
+        Value::Int(-1)
+    );
 }

 #[test]
 fn builtins_compare_versions_numeric_vs_alpha() {
    // Numeric component comes before alpha component
-    assert_eq!(eval("builtins.compareVersions \"2.3.1\" \"2.3a\""), Value::Int(1));
-    assert_eq!(eval("builtins.compareVersions \"2.3a\" \"2.3.1\""), Value::Int(-1));
+    assert_eq!(
+        eval("builtins.compareVersions \"2.3.1\" \"2.3a\""),
+        Value::Int(1)
+    );
+    assert_eq!(
+        eval("builtins.compareVersions \"2.3a\" \"2.3.1\""),
+        Value::Int(-1)
+    );
 }

 #[test]
 fn builtins_compare_versions_pre() {
    // "pre" is special: comes before everything except another "pre"
-    assert_eq!(eval("builtins.compareVersions \"2.3pre1\" \"2.3\""), Value::Int(-1));
-    assert_eq!(eval("builtins.compareVersions \"2.3pre3\" \"2.3pre12\""), Value::Int(-1));
-    assert_eq!(eval("builtins.compareVersions \"2.3pre1\" \"2.3c\""), Value::Int(-1));
-    assert_eq!(eval("builtins.compareVersions \"2.3pre1\" \"2.3q\""), Value::Int(-1));
+    assert_eq!(
+        eval("builtins.compareVersions \"2.3pre1\" \"2.3\""),
+        Value::Int(-1)
+    );
+    assert_eq!(
+        eval("builtins.compareVersions \"2.3pre3\" \"2.3pre12\""),
+        Value::Int(-1)
+    );
+    assert_eq!(
+        eval("builtins.compareVersions \"2.3pre1\" \"2.3c\""),
+        Value::Int(-1)
+    );
+    assert_eq!(
+        eval("builtins.compareVersions \"2.3pre1\" \"2.3q\""),
+        Value::Int(-1)
+    );
 }

 #[test]
 fn builtins_compare_versions_alpha() {
    // Alphabetic comparison
-    assert_eq!(eval("builtins.compareVersions \"2.3a\" \"2.3c\""), Value::Int(-1));
-    assert_eq!(eval("builtins.compareVersions \"2.3c\" \"2.3a\""), Value::Int(1));
+    assert_eq!(
+        eval("builtins.compareVersions \"2.3a\" \"2.3c\""),
+        Value::Int(-1)
+    );
+    assert_eq!(
+        eval("builtins.compareVersions \"2.3c\" \"2.3a\""),
+        Value::Int(1)
+    );
 }

 #[test]
--- a/nix-js/tests/builtins_store.rs
+++ b/nix-js/tests/builtins_store.rs
@@ -0,0 +1,228 @@
+mod utils;
+
+use std::sync::Once;
+
+use nix_js::value::Value;
+use utils::eval_result;
+
+fn init() {
+    static INIT: Once = Once::new();
+    INIT.call_once(|| {
+        #[cfg(not(feature = "daemon"))]
+        unsafe { std::env::set_var("NIX_JS_STORE_MODE", "simulated") };
+        #[cfg(feature = "daemon")]
+        unsafe { std::env::set_var("NIX_JS_STORE_MODE", "daemon") };
+    });
+}
+
+#[test]
+fn to_file_simple() {
+    init();
+
+    let result =
+        eval_result(r#"builtins.toFile "hello.txt" "Hello, World!""#).expect("Failed to evaluate");
+
+    match result {
+        Value::String(path) => {
+            assert!(path.contains("-hello.txt"));
+            assert!(std::path::Path::new(&path).exists());
+
+            let contents = std::fs::read_to_string(&path).expect("Failed to read file");
+            assert_eq!(contents, "Hello, World!");
+        }
+        _ => panic!("Expected string, got {:?}", result),
+    }
+}
+
+#[test]
+fn to_file_with_references() {
+    init();
+
+    let result = eval_result(
+        r#"
+            let
+              dep = builtins.toFile "dep.txt" "dependency";
+            in
+              builtins.toFile "main.txt" "Reference: ${dep}"
+        "#,
+    )
+    .expect("Failed to evaluate");
+
+    match result {
+        Value::String(path) => {
+            assert!(path.contains("-main.txt"));
+            let contents = std::fs::read_to_string(&path).expect("Failed to read file");
+            assert!(contents.contains("Reference: "));
+            assert!(contents.contains("-dep.txt"));
+        }
+        _ => panic!("Expected string"),
+    }
+}
+
+#[test]
+fn to_file_invalid_name_with_slash() {
+    init();
+
+    let result = eval_result(r#"builtins.toFile "foo/bar.txt" "content""#);
+
+    assert!(result.is_err());
+    assert!(
+        result
+            .unwrap_err()
+            .to_string()
+            .contains("name cannot contain '/'")
+    );
+}
+
+#[test]
+fn to_file_invalid_name_dot() {
+    init();
+
+    let result = eval_result(r#"builtins.toFile "." "content""#);
+
+    assert!(result.is_err());
+    assert!(result.unwrap_err().to_string().contains("invalid name"));
+}
+
+#[test]
+fn to_file_invalid_name_dotdot() {
+    init();
+
+    let result = eval_result(r#"builtins.toFile ".." "content""#);
+
+    assert!(result.is_err());
+    assert!(result.unwrap_err().to_string().contains("invalid name"));
+}
+
+#[test]
+fn store_path_validation_not_in_store() {
+    init();
+
+    let result = eval_result(r#"builtins.storePath "/tmp/foo""#);
+
+    assert!(result.is_err());
+    assert!(
+        result
+            .unwrap_err()
+            .to_string()
+            .contains("not in the Nix store")
+    );
+}
+
+#[test]
+fn store_path_validation_malformed_hash() {
+    init();
+
+    let dummy_file_result = eval_result(r#"builtins.toFile "dummy.txt" "content""#)
+        .expect("Failed to create dummy file");
+
+    let dummy_path = match dummy_file_result {
+        Value::String(ref p) => p.clone(),
+        _ => panic!("Expected string"),
+    };
+
+    let store_dir = std::path::Path::new(&dummy_path)
+        .parent()
+        .expect("Failed to get parent dir")
+        .to_str()
+        .expect("Failed to convert to string");
+
+    let test_path = format!("{}/invalid-hash-hello", store_dir);
+    let result = eval_result(&format!(r#"builtins.storePath "{}""#, test_path));
+
+    assert!(result.is_err());
+    let err_str = result.unwrap_err().to_string();
+    assert!(
+        err_str.contains("invalid") || err_str.contains("hash"),
+        "Expected hash validation error, got: {}",
+        err_str
+    );
+}
+
+#[test]
+fn store_path_validation_missing_name() {
+    init();
+
+    let dummy_file_result = eval_result(r#"builtins.toFile "dummy.txt" "content""#)
+        .expect("Failed to create dummy file");
+
+    let dummy_path = match dummy_file_result {
+        Value::String(ref p) => p.clone(),
+        _ => panic!("Expected string"),
+    };
+
+    let store_dir = std::path::Path::new(&dummy_path)
+        .parent()
+        .expect("Failed to get parent dir")
+        .to_str()
+        .expect("Failed to convert to string");
+
+    let test_path = format!("{}/abcd1234abcd1234abcd1234abcd1234", store_dir);
+    let result = eval_result(&format!(r#"builtins.storePath "{}""#, test_path));
+
+    assert!(result.is_err());
+    let err_str = result.unwrap_err().to_string();
+    assert!(
+        err_str.contains("missing name") || err_str.contains("format"),
+        "Expected missing name error, got: {}",
+        err_str
+    );
+}
+
+#[test]
+fn to_file_curried_application() {
+    init();
+
+    let result = eval_result(
+        r#"
+            let
+              makeFile = builtins.toFile "test.txt";
+            in
+              makeFile "test content"
+        "#,
+    )
+    .expect("Failed to evaluate");
+
+    match result {
+        Value::String(path) => {
+            assert!(path.contains("-test.txt"));
+            let contents = std::fs::read_to_string(&path).expect("Failed to read file");
+            assert_eq!(contents, "test content");
+        }
+        _ => panic!("Expected string"),
+    }
+}
+
+#[test]
+fn to_file_number_conversion() {
+    init();
+
+    let result = eval_result(r#"builtins.toFile "number.txt" (builtins.toString 42)"#)
+        .expect("Failed to evaluate");
+
+    match result {
+        Value::String(path) => {
+            let contents = std::fs::read_to_string(&path).expect("Failed to read file");
+            assert_eq!(contents, "42");
+        }
+        _ => panic!("Expected string"),
+    }
+}
+
+#[test]
+fn to_file_list_conversion() {
+    init();
+
+    let result = eval_result(
+        r#"builtins.toFile "list.txt" (builtins.concatStringsSep "\n" ["line1" "line2" "line3"])"#,
+    )
+    .expect("Failed to evaluate");
+
+    match result {
+        Value::String(path) => {
+            let contents = std::fs::read_to_string(&path).expect("Failed to read file");
+            assert_eq!(contents, "line1\nline2\nline3");
+        }
+        _ => panic!("Expected string"),
+    }
+}
--- a/nix-js/tests/derivation.rs
+++ b/nix-js/tests/derivation.rs
@@ -1,14 +1,14 @@
-use nix_js::context::Context;
+#![cfg(feature = "daemon")]
+
+mod utils;
+
 use nix_js::value::Value;
+use utils::{eval, eval_result};

 #[test]
 fn derivation_minimal() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation { name = "hello"; builder = "/bin/sh"; system = "x86_64-linux"; }"#,
-        )
-        .unwrap();
+    let result =
+        eval(r#"derivation { name = "hello"; builder = "/bin/sh"; system = "x86_64-linux"; }"#);

    match result {
        Value::AttrSet(attrs) => {
@@ -44,17 +44,14 @@ fn derivation_minimal() {

 #[test]
 fn derivation_with_args() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "test";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                args = ["-c" "echo hello"];
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "test";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            args = ["-c" "echo hello"];
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -69,12 +66,9 @@ fn derivation_with_args() {

 #[test]
 fn derivation_to_string() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"toString (derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; })"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"toString (derivation { name = "foo"; builder = "/bin/sh"; system = "x86_64-linux"; })"#,
+    );

    match result {
        Value::String(s) => assert_eq!(s, "/nix/store/xpcvxsx5sw4rbq666blz6sxqlmsqphmr-foo"),
@@ -84,8 +78,7 @@ fn derivation_to_string() {

 #[test]
 fn derivation_missing_name() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx.eval_code(r#"derivation { builder = "/bin/sh"; system = "x86_64-linux"; }"#);
+    let result = eval_result(r#"derivation { builder = "/bin/sh"; system = "x86_64-linux"; }"#);

    assert!(result.is_err());
    let err_msg = result.unwrap_err().to_string();
@@ -94,8 +87,7 @@ fn derivation_missing_name() {

 #[test]
 fn derivation_invalid_name_with_drv_suffix() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx.eval_code(
+    let result = eval_result(
        r#"derivation { name = "foo.drv"; builder = "/bin/sh"; system = "x86_64-linux"; }"#,
    );

@@ -106,8 +98,7 @@ fn derivation_invalid_name_with_drv_suffix() {

 #[test]
 fn derivation_missing_builder() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx.eval_code(r#"derivation { name = "test"; system = "x86_64-linux"; }"#);
+    let result = eval_result(r#"derivation { name = "test"; system = "x86_64-linux"; }"#);

    assert!(result.is_err());
    let err_msg = result.unwrap_err().to_string();
@@ -116,8 +107,7 @@ fn derivation_missing_builder() {

 #[test]
 fn derivation_missing_system() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx.eval_code(r#"derivation { name = "test"; builder = "/bin/sh"; }"#);
+    let result = eval_result(r#"derivation { name = "test"; builder = "/bin/sh"; }"#);

    assert!(result.is_err());
    let err_msg = result.unwrap_err().to_string();
@@ -126,18 +116,15 @@ fn derivation_missing_system() {

 #[test]
 fn derivation_with_env_vars() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "test";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                MY_VAR = "hello";
-                ANOTHER = "world";
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "test";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            MY_VAR = "hello";
+            ANOTHER = "world";
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -150,12 +137,9 @@ fn derivation_with_env_vars() {

 #[test]
 fn derivation_strict() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"builtins.derivationStrict { name = "test"; builder = "/bin/sh"; system = "x86_64-linux"; }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"builtins.derivationStrict { name = "test"; builder = "/bin/sh"; system = "x86_64-linux"; }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -169,12 +153,10 @@ fn derivation_strict() {

 #[test]
 fn derivation_deterministic_paths() {
-    let mut ctx = Context::new().unwrap();
-
    let expr = r#"derivation { name = "hello"; builder = "/bin/sh"; system = "x86_64-linux"; }"#;

-    let result1 = ctx.eval_code(expr).unwrap();
-    let result2 = ctx.eval_code(expr).unwrap();
+    let result1 = eval(expr);
+    let result2 = eval(expr);

    match (result1, result2) {
        (Value::AttrSet(attrs1), Value::AttrSet(attrs2)) => {
@@ -187,17 +169,14 @@ fn derivation_deterministic_paths() {

 #[test]
 fn derivation_escaping_in_aterm() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "test";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                args = ["-c" "echo \"hello\nworld\""];
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "test";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            args = ["-c" "echo \"hello\nworld\""];
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -210,17 +189,14 @@ fn derivation_escaping_in_aterm() {

 #[test]
 fn multi_output_two_outputs() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "multi";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                outputs = ["out" "dev"];
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "multi";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            outputs = ["out" "dev"];
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -271,17 +247,14 @@ fn multi_output_two_outputs() {

 #[test]
 fn multi_output_three_outputs() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "three";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                outputs = ["out" "dev" "doc"];
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "three";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            outputs = ["out" "dev" "doc"];
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -322,17 +295,14 @@ fn multi_output_three_outputs() {

 #[test]
 fn multi_output_backward_compat() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "compat";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                outputs = ["out"];
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "compat";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            outputs = ["out"];
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -351,47 +321,39 @@ fn multi_output_backward_compat() {

 #[test]
 fn multi_output_deterministic() {
-    let mut ctx = Context::new().unwrap();
-    let result1 = ctx
-        .eval_code(
-            r#"derivation {
-                name = "determ";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                outputs = ["out" "dev"];
-            }"#,
-        )
-        .unwrap();
+    let result1 = eval(
+        r#"derivation {
+            name = "determ";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            outputs = ["out" "dev"];
+        }"#,
+    );

-    let result2 = ctx
-        .eval_code(
-            r#"derivation {
-                name = "determ";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                outputs = ["out" "dev"];
-            }"#,
-        )
-        .unwrap();
+    let result2 = eval(
+        r#"derivation {
+            name = "determ";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            outputs = ["out" "dev"];
+        }"#,
+    );

    assert_eq!(result1, result2);
 }

 #[test]
 fn fixed_output_sha256_flat() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "fixed";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                outputHash = "0000000000000000000000000000000000000000000000000000000000000000";
-                outputHashAlgo = "sha256";
-                outputHashMode = "flat";
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "fixed";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            outputHash = "0000000000000000000000000000000000000000000000000000000000000000";
+            outputHashAlgo = "sha256";
+            outputHashMode = "flat";
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -419,17 +381,14 @@ fn fixed_output_sha256_flat() {

 #[test]
 fn fixed_output_default_algo() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "default";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                outputHash = "0000000000000000000000000000000000000000000000000000000000000000";
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "default";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            outputHash = "0000000000000000000000000000000000000000000000000000000000000000";
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -445,19 +404,16 @@ fn fixed_output_default_algo() {

 #[test]
 fn fixed_output_recursive_mode() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "recursive";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                outputHash = "1111111111111111111111111111111111111111111111111111111111111111";
-                outputHashAlgo = "sha256";
-                outputHashMode = "recursive";
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "recursive";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            outputHash = "1111111111111111111111111111111111111111111111111111111111111111";
+            outputHashAlgo = "sha256";
+            outputHashMode = "recursive";
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -478,8 +434,7 @@ fn fixed_output_recursive_mode() {

 #[test]
 fn fixed_output_rejects_multi_output() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx.eval_code(
+    let result = eval_result(
        r#"derivation {
            name = "invalid";
            builder = "/bin/sh";
@@ -496,8 +451,7 @@ fn fixed_output_rejects_multi_output() {

 #[test]
 fn fixed_output_invalid_hash_mode() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx.eval_code(
+    let result = eval_result(
        r#"derivation {
            name = "invalid";
            builder = "/bin/sh";
@@ -514,20 +468,17 @@ fn fixed_output_invalid_hash_mode() {

 #[test]
 fn structured_attrs_basic() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "struct";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                __structuredAttrs = true;
-                foo = "bar";
-                count = 42;
-                enabled = true;
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "struct";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            __structuredAttrs = true;
+            foo = "bar";
+            count = 42;
+            enabled = true;
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -542,18 +493,15 @@ fn structured_attrs_basic() {

 #[test]
 fn structured_attrs_nested() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "nested";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                __structuredAttrs = true;
-                data = { x = 1; y = [2 3]; };
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "nested";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            __structuredAttrs = true;
+            data = { x = 1; y = [2 3]; };
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -566,8 +514,7 @@ fn structured_attrs_nested() {

 #[test]
 fn structured_attrs_rejects_functions() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx.eval_code(
+    let result = eval_result(
        r#"derivation {
            name = "invalid";
            builder = "/bin/sh";
@@ -584,18 +531,15 @@ fn structured_attrs_rejects_functions() {

 #[test]
 fn structured_attrs_false() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "normal";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                __structuredAttrs = false;
-                foo = "bar";
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "normal";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            __structuredAttrs = false;
+            foo = "bar";
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -610,19 +554,16 @@ fn structured_attrs_false() {

 #[test]
 fn ignore_nulls_true() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "ignore";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                __ignoreNulls = true;
-                foo = "bar";
-                nullValue = null;
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "ignore";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            __ignoreNulls = true;
+            foo = "bar";
+            nullValue = null;
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -635,18 +576,15 @@ fn ignore_nulls_true() {

 #[test]
 fn ignore_nulls_false() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "keep";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                __ignoreNulls = false;
-                nullValue = null;
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "keep";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            __ignoreNulls = false;
+            nullValue = null;
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -661,20 +599,17 @@ fn ignore_nulls_false() {

 #[test]
 fn ignore_nulls_with_structured_attrs() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "combined";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                __structuredAttrs = true;
-                __ignoreNulls = true;
-                foo = "bar";
-                nullValue = null;
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "combined";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            __structuredAttrs = true;
+            __ignoreNulls = true;
+            foo = "bar";
+            nullValue = null;
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -688,21 +623,18 @@ fn ignore_nulls_with_structured_attrs() {

 #[test]
 fn all_features_combined() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "all";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                outputs = ["out" "dev"];
-                __structuredAttrs = true;
-                __ignoreNulls = true;
-                data = { x = 1; };
-                nullValue = null;
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "all";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            outputs = ["out" "dev"];
+            __structuredAttrs = true;
+            __ignoreNulls = true;
+            data = { x = 1; };
+            nullValue = null;
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
@@ -718,19 +650,16 @@ fn all_features_combined() {

 #[test]
 fn fixed_output_with_structured_attrs() {
-    let mut ctx = Context::new().unwrap();
-    let result = ctx
-        .eval_code(
-            r#"derivation {
-                name = "fixstruct";
-                builder = "/bin/sh";
-                system = "x86_64-linux";
-                outputHash = "abc123";
-                __structuredAttrs = true;
-                data = { key = "value"; };
-            }"#,
-        )
-        .unwrap();
+    let result = eval(
+        r#"derivation {
+            name = "fixstruct";
+            builder = "/bin/sh";
+            system = "x86_64-linux";
+            outputHash = "abc123";
+            __structuredAttrs = true;
+            data = { key = "value"; };
+        }"#,
+    );

    match result {
        Value::AttrSet(attrs) => {
--- a/nix-js/tests/io_operations.rs
+++ b/nix-js/tests/io_operations.rs
@@ -104,21 +104,18 @@ fn import_with_complex_dependency_graph() {
 // Tests for builtins.path

 #[test]
-fn test_path_with_file() {
+fn path_with_file() {
    let mut ctx = Context::new().unwrap();
    let temp_dir = tempfile::tempdir().unwrap();
    let test_file = temp_dir.path().join("test.txt");
    std::fs::write(&test_file, "Hello, World!").unwrap();

-    let expr = format!(
-        r#"builtins.path {{ path = {}; }}"#,
-        test_file.display()
-    );
+    let expr = format!(r#"builtins.path {{ path = {}; }}"#, test_file.display());
    let result = ctx.eval_code(&expr).unwrap();

    // Should return a store path string
    if let Value::String(store_path) = result {
-        assert!(store_path.starts_with("/nix/store/"));
+        assert!(store_path.starts_with(ctx.get_store_dir()));
        assert!(store_path.contains("test.txt"));
    } else {
        panic!("Expected string, got {:?}", result);
@@ -126,7 +123,7 @@ fn test_path_with_file() {
 }

 #[test]
-fn test_path_with_custom_name() {
+fn path_with_custom_name() {
    let mut ctx = Context::new().unwrap();
    let temp_dir = tempfile::tempdir().unwrap();
    let test_file = temp_dir.path().join("original.txt");
@@ -147,7 +144,7 @@ fn test_path_with_custom_name() {
 }

 #[test]
-fn test_path_with_directory_recursive() {
+fn path_with_directory_recursive() {
    let mut ctx = Context::new().unwrap();
    let temp_dir = tempfile::tempdir().unwrap();
    let test_dir = temp_dir.path().join("mydir");
@@ -162,7 +159,7 @@ fn test_path_with_directory_recursive() {
    let result = ctx.eval_code(&expr).unwrap();

    if let Value::String(store_path) = result {
-        assert!(store_path.starts_with("/nix/store/"));
+        assert!(store_path.starts_with(ctx.get_store_dir()));
        assert!(store_path.contains("mydir"));
    } else {
        panic!("Expected string, got {:?}", result);
@@ -170,7 +167,7 @@ fn test_path_with_directory_recursive() {
 }

 #[test]
-fn test_path_flat_with_file() {
+fn path_flat_with_file() {
    let mut ctx = Context::new().unwrap();
    let temp_dir = tempfile::tempdir().unwrap();
    let test_file = temp_dir.path().join("flat.txt");
@@ -183,14 +180,14 @@ fn test_path_flat_with_file() {
    let result = ctx.eval_code(&expr).unwrap();

    if let Value::String(store_path) = result {
-        assert!(store_path.starts_with("/nix/store/"));
+        assert!(store_path.starts_with(ctx.get_store_dir()));
    } else {
        panic!("Expected string, got {:?}", result);
    }
 }

 #[test]
-fn test_path_flat_with_directory_fails() {
+fn path_flat_with_directory_fails() {
    let mut ctx = Context::new().unwrap();
    let temp_dir = tempfile::tempdir().unwrap();
    let test_dir = temp_dir.path().join("mydir");
@@ -208,7 +205,7 @@ fn test_path_flat_with_directory_fails() {
 }

 #[test]
-fn test_path_nonexistent_fails() {
+fn path_nonexistent_fails() {
    let mut ctx = Context::new().unwrap();

    let expr = r#"builtins.path { path = "/nonexistent/path/that/should/not/exist"; }"#;
@@ -220,7 +217,7 @@ fn test_path_nonexistent_fails() {
 }

 #[test]
-fn test_path_missing_path_param() {
+fn path_missing_path_param() {
    let mut ctx = Context::new().unwrap();

    let expr = r#"builtins.path { name = "test"; }"#;
@@ -232,17 +229,14 @@ fn test_path_missing_path_param() {
 }

 #[test]
-fn test_path_with_sha256() {
+fn path_with_sha256() {
    let mut ctx = Context::new().unwrap();
    let temp_dir = tempfile::tempdir().unwrap();
    let test_file = temp_dir.path().join("hash_test.txt");
    std::fs::write(&test_file, "Test content for hashing").unwrap();

    // First, get the hash by calling without sha256
-    let expr1 = format!(
-        r#"builtins.path {{ path = {}; }}"#,
-        test_file.display()
-    );
+    let expr1 = format!(r#"builtins.path {{ path = {}; }}"#, test_file.display());
    let result1 = ctx.eval_code(&expr1).unwrap();
    let store_path1 = match result1 {
        Value::String(s) => s,
@@ -251,10 +245,7 @@ fn test_path_with_sha256() {

    // Compute the actual hash (for testing, we'll just verify the same path is returned)
    // In real usage, the user would know the hash beforehand
-    let expr2 = format!(
-        r#"builtins.path {{ path = {}; }}"#,
-        test_file.display()
-    );
+    let expr2 = format!(r#"builtins.path {{ path = {}; }}"#, test_file.display());
    let result2 = ctx.eval_code(&expr2).unwrap();
    let store_path2 = match result2 {
        Value::String(s) => s,
@@ -266,7 +257,7 @@ fn test_path_with_sha256() {
 }

 #[test]
-fn test_path_deterministic() {
+fn path_deterministic() {
    let mut ctx = Context::new().unwrap();
    let temp_dir = tempfile::tempdir().unwrap();
    let test_file = temp_dir.path().join("deterministic.txt");
--- a/nix-js/tests/path_operations.rs
+++ b/nix-js/tests/path_operations.rs
@@ -4,113 +4,113 @@ use nix_js::value::Value;
 use utils::{eval, eval_result};

 #[test]
-fn test_path_type_of() {
+fn path_type_of() {
    let result = eval("builtins.typeOf ./foo");
    assert_eq!(result, Value::String("path".to_string()));
 }

 #[test]
-fn test_is_path_true() {
+fn is_path_true() {
    let result = eval("builtins.isPath ./foo");
    assert_eq!(result, Value::Bool(true));
 }

 #[test]
-fn test_is_path_false_string() {
+fn is_path_false_string() {
    let result = eval(r#"builtins.isPath "./foo""#);
    assert_eq!(result, Value::Bool(false));
 }

 #[test]
-fn test_is_path_false_number() {
+fn is_path_false_number() {
    let result = eval("builtins.isPath 42");
    assert_eq!(result, Value::Bool(false));
 }

 #[test]
-fn test_path_concat_type() {
+fn path_concat_type() {
    // path + string = path
    let result = eval(r#"builtins.typeOf (./foo + "/bar")"#);
    assert_eq!(result, Value::String("path".to_string()));
 }

 #[test]
-fn test_string_path_concat_type() {
+fn string_path_concat_type() {
    // string + path = string
    let result = eval(r#"builtins.typeOf ("prefix-" + ./foo)"#);
    assert_eq!(result, Value::String("string".to_string()));
 }

 #[test]
-fn test_basename_of_path() {
+fn basename_of_path() {
    let result = eval("builtins.baseNameOf ./path/to/file.nix");
    assert!(matches!(result, Value::String(s) if s == "file.nix"));
 }

 #[test]
-fn test_basename_of_string() {
+fn basename_of_string() {
    let result = eval(r#"builtins.baseNameOf "/path/to/file.nix""#);
    assert_eq!(result, Value::String("file.nix".to_string()));
 }

 #[test]
-fn test_dir_of_path_type() {
+fn dir_of_path_type() {
    // dirOf preserves path type
    let result = eval("builtins.typeOf (builtins.dirOf ./path/to/file.nix)");
    assert_eq!(result, Value::String("path".to_string()));
 }

 #[test]
-fn test_dir_of_string_type() {
+fn dir_of_string_type() {
    // dirOf preserves string type
    let result = eval(r#"builtins.typeOf (builtins.dirOf "/path/to/file.nix")"#);
    assert_eq!(result, Value::String("string".to_string()));
 }

 #[test]
-fn test_path_equality() {
+fn path_equality() {
    // Same path should be equal
    let result = eval("./foo == ./foo");
    assert_eq!(result, Value::Bool(true));
 }

 #[test]
-fn test_path_not_equal_string() {
+fn path_not_equal_string() {
    // Paths and strings are different types - should not be equal
    let result = eval(r#"./foo == "./foo""#);
    assert_eq!(result, Value::Bool(false));
 }

 #[test]
-fn test_to_path_absolute() {
+fn to_path_absolute() {
    // toPath with absolute path returns string
    let result = eval(r#"builtins.toPath "/foo/bar""#);
    assert_eq!(result, Value::String("/foo/bar".to_string()));
 }

 #[test]
-fn test_to_path_type_is_string() {
+fn to_path_type_is_string() {
    // toPath returns a string, not a path
    let result = eval(r#"builtins.typeOf (builtins.toPath "/foo")"#);
    assert_eq!(result, Value::String("string".to_string()));
 }

 #[test]
-fn test_to_path_relative_fails() {
+fn to_path_relative_fails() {
    // toPath with relative path should fail
    let result = eval_result(r#"builtins.toPath "foo/bar""#);
    assert!(result.is_err());
 }

 #[test]
-fn test_to_path_empty_fails() {
+fn to_path_empty_fails() {
    // toPath with empty string should fail
    let result = eval_result(r#"builtins.toPath """#);
    assert!(result.is_err());
 }

 #[test]
-fn test_to_path_from_path_value() {
+fn to_path_from_path_value() {
    // toPath can accept a path value too (coerces to string first)
    let result = eval("builtins.toPath ./foo");
    // Should succeed and return the absolute path as a string
--- a/nix-js/tests/regex.rs
+++ b/nix-js/tests/regex.rs
@@ -4,7 +4,7 @@ use nix_js::value::{List, Value};
 use utils::eval;

 #[test]
-fn test_match_exact_full_string() {
+fn match_exact_full_string() {
    assert_eq!(
        eval(r#"builtins.match "foobar" "foobar""#),
        Value::List(List::new(vec![]))
@@ -12,12 +12,12 @@ fn test_match_exact_full_string() {
 }

 #[test]
-fn test_match_partial_returns_null() {
+fn match_partial_returns_null() {
    assert_eq!(eval(r#"builtins.match "foo" "foobar""#), Value::Null);
 }

 #[test]
-fn test_match_with_capture_groups() {
+fn match_with_capture_groups() {
    assert_eq!(
        eval(r#"builtins.match "(.*)\\.nix" "foobar.nix""#),
        Value::List(List::new(vec![Value::String("foobar".into())]))
@@ -25,7 +25,7 @@ fn test_match_with_capture_groups() {
 }

 #[test]
-fn test_match_multiple_capture_groups() {
+fn match_multiple_capture_groups() {
    assert_eq!(
        eval(r#"builtins.match "((.*)/)?([^/]*)\\.nix" "foobar.nix""#),
        Value::List(List::new(vec![
@@ -37,7 +37,7 @@ fn test_match_multiple_capture_groups() {
 }

 #[test]
-fn test_match_with_path() {
+fn match_with_path() {
    assert_eq!(
        eval(r#"builtins.match "((.*)/)?([^/]*)\\.nix" "/path/to/foobar.nix""#),
        Value::List(List::new(vec![
@@ -49,7 +49,7 @@ fn test_match_with_path() {
 }

 #[test]
-fn test_match_posix_space_class() {
+fn match_posix_space_class() {
    assert_eq!(
        eval(r#"builtins.match "[[:space:]]+([^[:space:]]+)[[:space:]]+" "  foo   ""#),
        Value::List(List::new(vec![Value::String("foo".into())]))
@@ -57,8 +57,11 @@ fn test_match_posix_space_class() {
 }

 #[test]
-fn test_match_posix_upper_class() {
-    assert_eq!(eval(r#"builtins.match "[[:space:]]+([[:upper:]]+)[[:space:]]+" "  foo   ""#), Value::Null);
+fn match_posix_upper_class() {
+    assert_eq!(
+        eval(r#"builtins.match "[[:space:]]+([[:upper:]]+)[[:space:]]+" "  foo   ""#),
+        Value::Null
+    );

    assert_eq!(
        eval(r#"builtins.match "[[:space:]]+([[:upper:]]+)[[:space:]]+" "  FOO   ""#),
@@ -67,7 +70,7 @@ fn test_match_posix_upper_class() {
 }

 #[test]
-fn test_match_quantifiers() {
+fn match_quantifiers() {
    assert_eq!(
        eval(r#"builtins.match "fo*" "f""#),
        Value::List(List::new(vec![]))
@@ -84,7 +87,7 @@ fn test_match_quantifiers() {
 }

 #[test]
-fn test_split_non_capturing() {
+fn split_non_capturing() {
    assert_eq!(
        eval(r#"builtins.split "foobar" "foobar""#),
        Value::List(List::new(vec![
@@ -96,7 +99,7 @@ fn test_split_non_capturing() {
 }

 #[test]
-fn test_split_no_match() {
+fn split_no_match() {
    assert_eq!(
        eval(r#"builtins.split "fo+" "f""#),
        Value::List(List::new(vec![Value::String("f".into())]))
@@ -104,7 +107,7 @@ fn test_split_no_match() {
 }

 #[test]
-fn test_split_with_capture_group() {
+fn split_with_capture_group() {
    assert_eq!(
        eval(r#"builtins.split "(fo*)" "foobar""#),
        Value::List(List::new(vec![
@@ -116,7 +119,7 @@ fn test_split_with_capture_group() {
 }

 #[test]
-fn test_split_multiple_matches() {
+fn split_multiple_matches() {
    assert_eq!(
        eval(r#"builtins.split "(b)" "foobarbaz""#),
        Value::List(List::new(vec![
@@ -130,7 +133,7 @@ fn test_split_multiple_matches() {
 }

 #[test]
-fn test_split_with_multiple_groups() {
+fn split_with_multiple_groups() {
    assert_eq!(
        eval(r#"builtins.split "(f)(o*)" "foo""#),
        Value::List(List::new(vec![
@@ -145,7 +148,7 @@ fn test_split_with_multiple_groups() {
 }

 #[test]
-fn test_split_with_optional_groups() {
+fn split_with_optional_groups() {
    assert_eq!(
        eval(r#"builtins.split "(a)|(c)" "abc""#),
        Value::List(List::new(vec![
@@ -159,7 +162,7 @@ fn test_split_with_optional_groups() {
 }

 #[test]
-fn test_split_greedy_matching() {
+fn split_greedy_matching() {
    assert_eq!(
        eval(r#"builtins.split "(o+)" "oooofoooo""#),
        Value::List(List::new(vec![
@@ -173,7 +176,7 @@ fn test_split_greedy_matching() {
 }

 #[test]
-fn test_split_posix_classes() {
+fn split_posix_classes() {
    assert_eq!(
        eval(r#"builtins.split "([[:upper:]]+)" "  FOO   ""#),
        Value::List(List::new(vec![
@@ -185,7 +188,7 @@ fn test_split_posix_classes() {
 }

 #[test]
-fn test_replace_basic() {
+fn replace_basic() {
    assert_eq!(
        eval(r#"builtins.replaceStrings ["o"] ["a"] "foobar""#),
        Value::String("faabar".into())
@@ -193,7 +196,7 @@ fn test_replace_basic() {
 }

 #[test]
-fn test_replace_with_empty() {
+fn replace_with_empty() {
    assert_eq!(
        eval(r#"builtins.replaceStrings ["o"] [""] "foobar""#),
        Value::String("fbar".into())
@@ -201,7 +204,7 @@ fn test_replace_with_empty() {
 }

 #[test]
-fn test_replace_multiple_patterns() {
+fn replace_multiple_patterns() {
    assert_eq!(
        eval(r#"builtins.replaceStrings ["oo" "a"] ["a" "oo"] "foobar""#),
        Value::String("faboor".into())
@@ -209,7 +212,7 @@ fn test_replace_multiple_patterns() {
 }

 #[test]
-fn test_replace_first_match_wins() {
+fn replace_first_match_wins() {
    assert_eq!(
        eval(r#"builtins.replaceStrings ["oo" "oo"] ["u" "i"] "foobar""#),
        Value::String("fubar".into())
@@ -217,7 +220,7 @@ fn test_replace_first_match_wins() {
 }

 #[test]
-fn test_replace_empty_pattern() {
+fn replace_empty_pattern() {
    assert_eq!(
        eval(r#"builtins.replaceStrings [""] ["X"] "abc""#),
        Value::String("XaXbXcX".into())
@@ -225,7 +228,7 @@ fn test_replace_empty_pattern() {
 }

 #[test]
-fn test_replace_empty_pattern_empty_string() {
+fn replace_empty_pattern_empty_string() {
    assert_eq!(
        eval(r#"builtins.replaceStrings [""] ["X"] """#),
        Value::String("X".into())
@@ -233,7 +236,7 @@ fn test_replace_empty_pattern_empty_string() {
 }

 #[test]
-fn test_replace_simple_char() {
+fn replace_simple_char() {
    assert_eq!(
        eval(r#"builtins.replaceStrings ["-"] ["_"] "a-b""#),
        Value::String("a_b".into())
@@ -241,7 +244,7 @@ fn test_replace_simple_char() {
 }

 #[test]
-fn test_replace_longer_pattern() {
+fn replace_longer_pattern() {
    assert_eq!(
        eval(r#"builtins.replaceStrings ["oo"] ["u"] "foobar""#),
        Value::String("fubar".into())
@@ -249,15 +252,14 @@ fn test_replace_longer_pattern() {
 }

 #[test]
-fn test_replace_different_lengths() {
-    let result = std::panic::catch_unwind(|| {
-        eval(r#"builtins.replaceStrings ["a" "b"] ["x"] "test""#)
-    });
+fn replace_different_lengths() {
+    let result =
+        std::panic::catch_unwind(|| eval(r#"builtins.replaceStrings ["a" "b"] ["x"] "test""#));
    assert!(result.is_err());
 }

 #[test]
-fn test_split_version_simple() {
+fn split_version_simple() {
    assert_eq!(
        eval(r#"builtins.splitVersion "1.2.3""#),
        Value::List(List::new(vec![
@@ -269,7 +271,7 @@ fn test_split_version_simple() {
 }

 #[test]
-fn test_split_version_with_pre() {
+fn split_version_with_pre() {
    assert_eq!(
        eval(r#"builtins.splitVersion "2.3.0pre1234""#),
        Value::List(List::new(vec![
@@ -283,7 +285,7 @@ fn test_split_version_with_pre() {
 }

 #[test]
-fn test_split_version_with_letters() {
+fn split_version_with_letters() {
    assert_eq!(
        eval(r#"builtins.splitVersion "2.3a""#),
        Value::List(List::new(vec![
@@ -295,7 +297,7 @@ fn test_split_version_with_letters() {
 }

 #[test]
-fn test_split_version_with_dashes() {
+fn split_version_with_dashes() {
    assert_eq!(
        eval(r#"builtins.splitVersion "2.3-beta1""#),
        Value::List(List::new(vec![
@@ -308,7 +310,7 @@ fn test_split_version_with_dashes() {
 }

 #[test]
-fn test_split_version_empty() {
+fn split_version_empty() {
    assert_eq!(
        eval(r#"builtins.splitVersion """#),
        Value::List(List::new(vec![]))
--- a/nix-js/tests/string_context.rs
+++ b/nix-js/tests/string_context.rs
@@ -152,8 +152,10 @@ fn string_add_merges_context() {

 #[test]
 fn context_in_derivation_args() {
-    let result = eval(
-        r#"
+    let mut ctx = Context::new().unwrap();
+    let result = ctx
+        .eval_code(
+            r#"
        let
          dep = derivation { name = "dep"; builder = "/bin/sh"; system = "x86_64-linux"; };
          drv = derivation {
@@ -164,10 +166,11 @@ fn context_in_derivation_args() {
          };
        in drv.drvPath
        "#,
-    );
+        )
+        .unwrap();
    match result {
        Value::String(s) => {
-            assert!(s.starts_with("/nix/store/"), "Should be a store path");
+            assert!(s.starts_with(ctx.get_store_dir()), "Should be a store path");
            assert!(s.ends_with(".drv"), "Should be a .drv file");
        }
        _ => panic!("Expected String, got {:?}", result),
@@ -176,8 +179,10 @@ fn context_in_derivation_args() {

 #[test]
 fn context_in_derivation_env() {
-    let result = eval(
-        r#"
+    let mut ctx = Context::new().unwrap();
+    let result = ctx
+        .eval_code(
+            r#"
        let
          dep = derivation { name = "dep"; builder = "/bin/sh"; system = "x86_64-linux"; };
          drv = derivation {
@@ -188,10 +193,11 @@ fn context_in_derivation_env() {
          };
        in drv.drvPath
        "#,
-    );
+        )
+        .unwrap();
    match result {
        Value::String(s) => {
-            assert!(s.starts_with("/nix/store/"), "Should be a store path");
+            assert!(s.starts_with(ctx.get_store_dir()), "Should be a store path");
            assert!(s.ends_with(".drv"), "Should be a .drv file");
        }
        _ => panic!("Expected String, got {:?}", result),
@@ -213,16 +219,19 @@ fn tostring_preserves_context() {

 #[test]
 fn interpolation_derivation_returns_outpath() {
-    let result = eval(
-        r#"
+    let mut ctx = Context::new().unwrap();
+    let result = ctx
+        .eval_code(
+            r#"
        let
          drv = derivation { name = "test"; builder = "/bin/sh"; system = "x86_64-linux"; };
        in "${drv}"
        "#,
-    );
+        )
+        .unwrap();
    match result {
        Value::String(s) => {
-            assert!(s.starts_with("/nix/store/"), "Should be a store path");
+            assert!(s.starts_with(ctx.get_store_dir()), "Should be a store path");
            assert!(s.ends_with("-test"), "Should end with derivation name");
        }
        _ => panic!("Expected String, got {:?}", result),
@@ -288,3 +297,95 @@ fn interpolation_derivation_equals_tostring() {
    );
    assert_eq!(result, Value::Bool(true));
 }
+
+#[test]
+fn substring_preserves_context() {
+    let result = eval(
+        r#"
+        let
+          drv = derivation { name = "test"; builder = "/bin/sh"; system = "x86_64-linux"; };
+          str = builtins.toString drv;
+          sub = builtins.substring 0 10 str;
+        in builtins.hasContext sub
+        "#,
+    );
+    assert_eq!(result, Value::Bool(true));
+}
+
+#[test]
+fn substring_zero_length_preserves_context() {
+    let result = eval(
+        r#"
+        let
+          drv = derivation { name = "test"; builder = "/bin/sh"; system = "x86_64-linux"; };
+          str = builtins.toString drv;
+          empty = builtins.substring 0 0 str;
+        in builtins.hasContext empty
+        "#,
+    );
+    assert_eq!(result, Value::Bool(true));
+}
+
+#[test]
+fn substring_zero_length_empty_value() {
+    let result = eval(
+        r#"
+        let
+          drv = derivation { name = "test"; builder = "/bin/sh"; system = "x86_64-linux"; };
+          str = builtins.toString drv;
+          empty = builtins.substring 0 0 str;
+        in empty == ""
+        "#,
+    );
+    assert_eq!(result, Value::Bool(true));
+}
+
+#[test]
+#[allow(non_snake_case)]
+fn concatStringsSep_preserves_context() {
+    let result = eval(
+        r#"
+        let
+          drv1 = derivation { name = "test1"; builder = "/bin/sh"; system = "x86_64-linux"; };
+          drv2 = derivation { name = "test2"; builder = "/bin/sh"; system = "x86_64-linux"; };
+          str1 = builtins.toString drv1;
+          str2 = builtins.toString drv2;
+          combined = builtins.concatStringsSep ":" [str1 str2];
+        in builtins.hasContext combined
+        "#,
+    );
+    assert_eq!(result, Value::Bool(true));
+}
+
+#[test]
+#[allow(non_snake_case)]
+fn concatStringsSep_merges_contexts() {
+    let result = eval(
+        r#"
+        let
+          drv1 = derivation { name = "test1"; builder = "/bin/sh"; system = "x86_64-linux"; };
+          drv2 = derivation { name = "test2"; builder = "/bin/sh"; system = "x86_64-linux"; };
+          str1 = builtins.toString drv1;
+          str2 = builtins.toString drv2;
+          combined = builtins.concatStringsSep ":" [str1 str2];
+          ctx = builtins.getContext combined;
+        in builtins.length (builtins.attrNames ctx)
+        "#,
+    );
+    assert_eq!(result, Value::Int(2));
+}
+
+#[test]
+#[allow(non_snake_case)]
+fn concatStringsSep_separator_has_context() {
+    let result = eval(
+        r#"
+        let
+          drv = derivation { name = "test"; builder = "/bin/sh"; system = "x86_64-linux"; };
+          sep = builtins.toString drv;
+          combined = builtins.concatStringsSep sep ["a" "b"];
+        in builtins.hasContext combined
+        "#,
+    );
+    assert_eq!(result, Value::Bool(true));
+}
Author	SHA1	Message	Date
imxyy_soope_	cf0af81939	feat: nix_nar	2026-01-18 01:04:44 +08:00
imxyy_soope_	2ad662c765	feat: initial nix-daemon implementation	2026-01-18 01:04:25 +08:00
imxyy_soope_	52bf46407a	feat: string context	2026-01-18 00:52:31 +08:00
imxyy_soope_	513b43965c	feat: do not use Object.defineProperty?	2026-01-18 00:52:11 +08:00
imxyy_soope_	09bfbca64a	refactor: tidy; fix runtime path resolution	2026-01-17 16:42:10 +08:00