feat(parsing): add Nix language parser

Cargo.toml

@@ -100,6 +100,7 @@ serde_json5 = "0.2.1"
 tree-sitter-swift = "0.7.2"
 tree-sitter-lua = "0.5.0"
 tree-sitter-clojure-orchard = "0.2.5"
+tree-sitter-nix = "0.3.0"
 glob = "0.3.3"
 async-trait = "0.1.89"
 reqwest = { version = "0.12", default-features = false, features = ["json", "rustls-tls"] }

contributing/parsers/grammar-versions.lock

@@ -74,6 +74,12 @@
       "updated": "2025-07-27T12:20:37-07:00",
       "abi_version": "15"
     },
+    "nix": {
+      "repo": "https://github.com/nix-community/tree-sitter-nix",
+      "version": "0.3.0",
+      "updated": "2026-05-21",
+      "abi_version": "15"
+    },
     "typescript": {
       "repo": "https://github.com/tree-sitter/tree-sitter-typescript",
       "commit": "75b3874edb2dc714fb1fd77a32013d0f8699989f",

contributing/parsers/nix/AUDIT_REPORT.md

@@ -0,0 +1,27 @@
+# Nix Parser Symbol Extraction Coverage Report
+
+## Summary
+- Key nodes: 18/18 (100%)
+- Total grammar nodes: 63
+- Total implemented: 56
+- Symbol kinds extracted: {"Variable", "Parameter", "Function"}
+
+## Key Nodes Coverage
+- [✓] source_code
+- [✓] binding
+- [✓] attrset_expression
+- [✓] rec_attrset_expression
+- [✓] let_expression
+- [✓] function_expression
+- [✓] formals
+- [✓] formal
+- [✓] inherit
+- [✓] inherit_from
+- [✓] apply_expression
+- [✓] select_expression
+- [✓] attrpath
+- [✓] identifier
+- [✓] if_expression
+- [✓] assert_expression
+- [✓] with_expression
+- [✓] comment

contributing/parsers/nix/GRAMMAR_ANALYSIS.md

@@ -0,0 +1,90 @@
+# Nix Grammar Analysis
+
+*Generated: 2026-05-21 12:23:48 UTC*
+
+## Statistics
+- Total nodes in grammar JSON: 36
+- Nodes found in comprehensive.nix: 63
+- Nodes handled by parser: 56
+- Symbol kinds extracted: 3
+
+## Successfully Handled Nodes
+These nodes are in examples and handled by parser:
+- !=
+- "
+- ${
+- ''
+- (
+- )
+- *
+- +
+- .
+- /
+- ;
+- <
+- ==
+- [
+- ]
+- apply_expression
+- assert
+- assert_expression
+- attrpath
+- attrset_expression
+- binary_expression
+- binding
+- binding_set
+- comment
+- else
+- formal
+- formals
+- function_expression
+- identifier
+- if
+- if_expression
+- in
+- indented_string_expression
+- inherit
+- inherit_from
+- integer_expression
+- interpolation
+- let
+- let_expression
+- list_expression
+- parenthesized_expression
+- path_expression
+- path_fragment
+- rec
+- rec_attrset_expression
+- select_expression
+- source_code
+- spath_expression
+- string_expression
+- string_fragment
+- then
+- variable_expression
+- with
+- with_expression
+- {
+- }
+
+## Implementation Gaps
+These nodes appear in comprehensive.nix but aren't handled:
+- ,
+- :
+- =
+- ?
+- @
+- ellipses
+- inherited_attrs
+
+## Missing from Examples
+These grammar nodes aren't in comprehensive.nix:
+- float_expression
+- has_attr_expression
+- unary_expression
+
+## Symbol Kinds Extracted
+- Function
+- Parameter
+- Variable
+