[pitboss/grind] deferred session-0001 (20260522T163126Z-7d60)

src/dynamic/corpus/json_parse/javascript.rs

@@ -1,17 +1,19 @@
-//! JavaScript `Cap::JSON_PARSE` payloads — `JSON.parse` then deep
-//! assign / `Object.assign` chain.
+//! JavaScript `Cap::JSON_PARSE` payloads.
 //!
-//! Same canary oracle as the Phase 10 PROTOTYPE_POLLUTION corpus
-//! ([`crate::dynamic::oracle::ProbePredicate::PrototypeCanaryTouched`]).
-//! The harness routes both payloads through `JSON.parse` first to
-//! exercise the parse-then-assign flow specifically (whereas the
-//! Phase 10 corpus passes the JSON literal directly to the deep-merge
-//! sink without an intervening parse).
+//! Covers two oracle shapes: the prototype-canary pair reuses the
+//! Phase 10 PROTOTYPE_POLLUTION canary
+//! ([`crate::dynamic::oracle::ProbePredicate::PrototypeCanaryTouched`])
+//! against a `JSON.parse`-then-deep-merge fixture, and the depth-bomb
+//! pair drives `JSON.parse` past the 64-level depth budget for the
+//! [`crate::dynamic::oracle::ProbePredicate::JsonParseExcessiveDepth`]
+//! oracle.  The depth pair shares a single fixture; the payload tag
+//! (`NYX_JSON_DEEP` vs `NYX_JSON_SHALLOW`) picks the branch.
 
 use super::super::{CuratedPayload, Oracle, PayloadProvenance, PayloadRef};
 use crate::dynamic::oracle::ProbePredicate;
 
 const CANARY: &str = "__nyx_canary";
+const MAX_DEPTH: u32 = 64;
 
 pub const PAYLOADS: &[CuratedPayload] = &[
     CuratedPayload {
@@ -48,4 +50,44 @@ pub const PAYLOADS: &[CuratedPayload] = &[
         benign_control: None,
         no_benign_control_rationale: None,
     },
+    CuratedPayload {
+        bytes: b"NYX_JSON_DEEP",
+        label: "json-parse-js-depth-bomb",
+        oracle: Oracle::SinkProbe {
+            predicates: &[ProbePredicate::JsonParseExcessiveDepth {
+                max_depth: MAX_DEPTH,
+            }],
+        },
+        is_benign: false,
+        provenance: PayloadProvenance::Curated,
+        since_corpus_version: 15,
+        deprecated_at_corpus_version: None,
+        fixture_paths: &["tests/dynamic_fixtures/json_parse_depth/javascript/vuln.js"],
+        oob_nonce_slot: false,
+        probe_predicates: &[ProbePredicate::JsonParseExcessiveDepth {
+            max_depth: MAX_DEPTH,
+        }],
+        benign_control: Some(PayloadRef {
+            label: "json-parse-js-depth-shallow",
+        }),
+        no_benign_control_rationale: None,
+    },
+    CuratedPayload {
+        bytes: b"NYX_JSON_SHALLOW",
+        label: "json-parse-js-depth-shallow",
+        oracle: Oracle::SinkProbe {
+            predicates: &[ProbePredicate::JsonParseExcessiveDepth {
+                max_depth: MAX_DEPTH,
+            }],
+        },
+        is_benign: true,
+        provenance: PayloadProvenance::Curated,
+        since_corpus_version: 15,
+        deprecated_at_corpus_version: None,
+        fixture_paths: &["tests/dynamic_fixtures/json_parse_depth/javascript/vuln.js"],
+        oob_nonce_slot: false,
+        probe_predicates: &[],
+        benign_control: None,
+        no_benign_control_rationale: None,
+    },
 ];

src/dynamic/corpus/json_parse/ruby.rs

@@ -1,10 +1,18 @@
-//! Ruby `Cap::JSON_PARSE` payloads — `JSON.parse` then recursive
-//! `Hash#deep_merge!` on a shared sentinel object.
+//! Ruby `Cap::JSON_PARSE` payloads.
+//!
+//! Covers two oracle shapes: the prototype-canary pair reuses the
+//! Phase 10 PROTOTYPE_POLLUTION canary against a `JSON.parse` then
+//! recursive `Hash#deep_merge!` fixture, and the depth-bomb pair
+//! drives `JSON.parse` past the 64-level depth budget for the
+//! [`crate::dynamic::oracle::ProbePredicate::JsonParseExcessiveDepth`]
+//! oracle.  The depth pair shares a single fixture; the payload tag
+//! (`NYX_JSON_DEEP` vs `NYX_JSON_SHALLOW`) picks the branch.
 
 use super::super::{CuratedPayload, Oracle, PayloadProvenance, PayloadRef};
 use crate::dynamic::oracle::ProbePredicate;
 
 const CANARY: &str = "__nyx_canary";
+const MAX_DEPTH: u32 = 64;
 
 pub const PAYLOADS: &[CuratedPayload] = &[
     CuratedPayload {
@@ -41,4 +49,44 @@ pub const PAYLOADS: &[CuratedPayload] = &[
         benign_control: None,
         no_benign_control_rationale: None,
     },
+    CuratedPayload {
+        bytes: b"NYX_JSON_DEEP",
+        label: "json-parse-ruby-depth-bomb",
+        oracle: Oracle::SinkProbe {
+            predicates: &[ProbePredicate::JsonParseExcessiveDepth {
+                max_depth: MAX_DEPTH,
+            }],
+        },
+        is_benign: false,
+        provenance: PayloadProvenance::Curated,
+        since_corpus_version: 15,
+        deprecated_at_corpus_version: None,
+        fixture_paths: &["tests/dynamic_fixtures/json_parse_depth/ruby/vuln.rb"],
+        oob_nonce_slot: false,
+        probe_predicates: &[ProbePredicate::JsonParseExcessiveDepth {
+            max_depth: MAX_DEPTH,
+        }],
+        benign_control: Some(PayloadRef {
+            label: "json-parse-ruby-depth-shallow",
+        }),
+        no_benign_control_rationale: None,
+    },
+    CuratedPayload {
+        bytes: b"NYX_JSON_SHALLOW",
+        label: "json-parse-ruby-depth-shallow",
+        oracle: Oracle::SinkProbe {
+            predicates: &[ProbePredicate::JsonParseExcessiveDepth {
+                max_depth: MAX_DEPTH,
+            }],
+        },
+        is_benign: true,
+        provenance: PayloadProvenance::Curated,
+        since_corpus_version: 15,
+        deprecated_at_corpus_version: None,
+        fixture_paths: &["tests/dynamic_fixtures/json_parse_depth/ruby/vuln.rb"],
+        oob_nonce_slot: false,
+        probe_predicates: &[],
+        benign_control: None,
+        no_benign_control_rationale: None,
+    },
 ];

src/dynamic/lang/js_shared.rs

@@ -629,6 +629,18 @@ pub fn emit(spec: &HarnessSpec, is_typescript: bool) -> Result<HarnessSource, Un
         return Ok(emit_prototype_pollution_harness(spec));
     }
 
+    // Phase 11 (Track J.9): JSON_PARSE depth-bomb short-circuit.  The
+    // synthetic harness monkey-patches `JSON.parse`, walks the parsed
+    // value iteratively to record maximum nesting depth, emits a
+    // `ProbeKind::JsonParse { depth, excessive_depth }` record, then
+    // routes the payload through the fixture entry.  RangeError-style
+    // V8 stack-exhaustion paths emit `JsonParse { depth: 0,
+    // excessive_depth: true }` so the predicate still fires when the
+    // engine rejects the input outright.
+    if spec.expected_cap == crate::labels::Cap::JSON_PARSE {
+        return Ok(emit_json_parse_harness(spec));
+    }
+
     // Phase 19 (Track M.1): ClassMethod short-circuit.  Same shape gap
     // closer as the Python emitter — instantiate the class via its
     // zero-arg constructor (falling back to a stubbed-dependency ctor
@@ -1957,6 +1969,135 @@ console.log(JSON.stringify({{
     }
 }
 
+/// Phase 11 (Track J.9) — JSON_PARSE depth-bomb harness for Node.
+///
+/// Monkey-patches `JSON.parse` with a wrapper that calls the original
+/// parser, walks the resulting value iteratively (no recursion stack)
+/// to compute maximum nesting depth, emits a
+/// `ProbeKind::JsonParse { depth, excessive_depth }` record, then
+/// returns the parsed value verbatim.  A `RangeError` raised by V8 on
+/// excessively-deep input is caught and converted into a
+/// `JsonParse { depth: 0, excessive_depth: true }` probe before the
+/// error is re-thrown — matching the Python harness's
+/// `RecursionError` handling.
+///
+/// Mirrors `crate::dynamic::lang::python::emit_json_parse_harness`.
+pub fn emit_json_parse_harness(spec: &HarnessSpec) -> HarnessSource {
+    let shim = probe_shim();
+    let entry_stem = derive_js_entry_stem(&spec.entry_file);
+    let entry_name = if spec.entry_name.is_empty() {
+        "run".to_owned()
+    } else {
+        spec.entry_name.clone()
+    };
+    let body = format!(
+        r#"// Nyx dynamic harness — JSON_PARSE depth checks (Phase 11 / Track J.9).
+{shim}
+
+const _NYX_MAX_WALK = 4096;
+
+function _nyx_count_depth(parsed) {{
+  let maxDepth = 0;
+  const stack = [[parsed, 1]];
+  let visited = 0;
+  while (stack.length > 0) {{
+    const [cur, depth] = stack.pop();
+    visited += 1;
+    if (visited > _NYX_MAX_WALK) break;
+    if (depth > maxDepth) maxDepth = depth;
+    if (cur !== null && typeof cur === 'object') {{
+      if (Array.isArray(cur)) {{
+        for (let i = 0; i < cur.length; i += 1) {{
+          stack.push([cur[i], depth + 1]);
+        }}
+      }} else {{
+        for (const k of Object.keys(cur)) {{
+          stack.push([cur[k], depth + 1]);
+        }}
+      }}
+    }}
+  }}
+  return maxDepth;
+}}
+
+function _nyx_json_parse_probe(depth, excessive) {{
+  const p = process.env.NYX_PROBE_PATH;
+  if (!p) return;
+  const rec = {{
+    sink_callee: 'JSON.parse',
+    args: [{{ kind: 'Int', value: depth | 0 }}],
+    captured_at_ns: Number(process.hrtime.bigint()),
+    payload_id: process.env.NYX_PAYLOAD_ID || '',
+    kind: {{
+      kind: 'JsonParse',
+      depth: depth | 0,
+      excessive_depth: !!excessive,
+    }},
+    witness: __nyx_witness('JSON.parse', [depth | 0]),
+  }};
+  try {{
+    require('fs').appendFileSync(p, JSON.stringify(rec) + '\n');
+  }} catch (e) {{
+    // best-effort
+  }}
+}}
+
+const _nyx_orig_json_parse = JSON.parse;
+
+JSON.parse = function _nyx_json_parse_with_depth(text, reviver) {{
+  let parsed;
+  try {{
+    parsed = _nyx_orig_json_parse(text, reviver);
+  }} catch (e) {{
+    // V8 raises `RangeError: Maximum call stack size exceeded` on
+    // deeply-nested input.  Emit the excessive-depth probe before
+    // re-raising so the oracle still fires.
+    if (e instanceof RangeError) {{
+      _nyx_json_parse_probe(0, true);
+    }}
+    throw e;
+  }}
+  const depth = _nyx_count_depth(parsed);
+  _nyx_json_parse_probe(depth, depth > 64);
+  return parsed;
+}};
+
+function _nyx_json_parse_via_fixture(payload) {{
+  let _entry;
+  try {{
+    _entry = require('./{entry_stem}');
+  }} catch (e) {{
+    process.stderr.write('NYX_IMPORT_ERROR: ' + e.message + '\n');
+    process.exit(77);
+  }}
+  const fn =
+    _entry && (typeof _entry === 'function' ? _entry : _entry['{entry_name}']);
+  if (typeof fn !== 'function') {{
+    return false;
+  }}
+  try {{
+    fn(payload);
+  }} catch (e) {{
+    // Parser errors / depth-induced throws are expected on the vuln
+    // payload; the probe is already emitted.
+  }}
+  return true;
+}}
+
+const payload = process.env.NYX_PAYLOAD || '';
+_nyx_json_parse_via_fixture(payload);
+console.log('__NYX_SINK_HIT__');
+"#
+    );
+    HarnessSource {
+        source: body,
+        filename: "harness.js".to_owned(),
+        command: vec!["node".to_owned(), "harness.js".to_owned()],
+        extra_files: Vec::new(),
+        entry_subpath: None,
+    }
+}
+
 /// Phase 26 — Node chain-step harness (shared between JS + TS emitters).
 ///
 /// Splices the Node probe shim ([`probe_shim`]) in front of a minimal
@@ -3436,4 +3577,92 @@ mod tests {
         );
         let _ = std::fs::remove_dir_all(&dir);
     }
+
+    fn make_json_parse_spec(entry_file: &str, entry_name: &str) -> HarnessSpec {
+        let mut spec = make_spec(EntryKind::Function, entry_name, PayloadSlot::Param(0));
+        spec.expected_cap = Cap::JSON_PARSE;
+        spec.entry_file = entry_file.into();
+        spec.entry_name = entry_name.into();
+        spec
+    }
+
+    #[test]
+    fn emit_dispatches_to_json_parse_harness_when_cap_is_json_parse() {
+        let h = emit(
+            &make_json_parse_spec(
+                "tests/dynamic_fixtures/json_parse_depth/javascript/vuln.js",
+                "run",
+            ),
+            false,
+        )
+        .unwrap();
+        assert!(
+            h.source.contains("_nyx_json_parse_with_depth"),
+            "dispatcher must select the JSON_PARSE depth harness: {}",
+            h.source
+        );
+        assert!(
+            h.source.contains("kind: 'JsonParse'"),
+            "JSON_PARSE harness must emit JsonParse probes",
+        );
+    }
+
+    #[test]
+    fn emit_json_parse_harness_monkey_patches_json_parse() {
+        let h = emit_json_parse_harness(&make_json_parse_spec(
+            "tests/dynamic_fixtures/json_parse_depth/javascript/vuln.js",
+            "run",
+        ));
+        assert!(h.source.contains("const _nyx_orig_json_parse = JSON.parse"));
+        assert!(
+            h.source
+                .contains("JSON.parse = function _nyx_json_parse_with_depth")
+        );
+        assert!(h.source.contains("function _nyx_count_depth(parsed)"));
+    }
+
+    #[test]
+    fn emit_json_parse_harness_emits_depth_fields() {
+        let h = emit_json_parse_harness(&make_json_parse_spec(
+            "tests/dynamic_fixtures/json_parse_depth/javascript/vuln.js",
+            "run",
+        ));
+        assert!(h.source.contains("depth: depth | 0"));
+        assert!(h.source.contains("excessive_depth: !!excessive"));
+        assert!(h.source.contains("depth > 64"));
+        assert!(h.source.contains("__NYX_SINK_HIT__"));
+    }
+
+    #[test]
+    fn emit_json_parse_harness_handles_range_error() {
+        let h = emit_json_parse_harness(&make_json_parse_spec(
+            "tests/dynamic_fixtures/json_parse_depth/javascript/vuln.js",
+            "run",
+        ));
+        assert!(h.source.contains("e instanceof RangeError"));
+        assert!(h.source.contains("_nyx_json_parse_probe(0, true)"));
+    }
+
+    #[test]
+    fn emit_json_parse_harness_routes_through_fixture_require() {
+        let h = emit_json_parse_harness(&make_json_parse_spec(
+            "tests/dynamic_fixtures/json_parse_depth/javascript/vuln.js",
+            "run",
+        ));
+        assert!(
+            h.source
+                .contains("function _nyx_json_parse_via_fixture(payload)")
+        );
+        assert!(h.source.contains("require('./vuln')"));
+        assert!(h.source.contains("_entry['run']"));
+        assert_eq!(h.filename, "harness.js");
+        assert!(h.extra_files.is_empty());
+    }
+
+    #[test]
+    fn emit_json_parse_harness_derives_entry_stem_from_entry_file() {
+        let h =
+            emit_json_parse_harness(&make_json_parse_spec("/abs/path/benign.js", "run"));
+        assert!(h.source.contains("require('./benign')"));
+    }
 }

src/dynamic/lang/ruby.rs

@@ -447,6 +447,18 @@ pub fn emit(spec: &HarnessSpec) -> Result<HarnessSource, UnsupportedReason> {
         return Ok(emit_open_redirect_harness(spec));
     }
 
+    // Phase 11 (Track J.9): JSON_PARSE depth-bomb short-circuit.  The
+    // synthetic harness rebinds `JSON.parse` to a depth-counting
+    // wrapper, walks the parsed value iteratively, and emits a
+    // `ProbeKind::JsonParse { depth, excessive_depth }` record before
+    // returning the parsed value.  `JSON::NestingError` (raised by the
+    // Ruby json gem when the input exceeds `max_nesting`) is caught
+    // and converted into a `JsonParse { depth: 0, excessive_depth:
+    // true }` probe before the error is re-raised.
+    if spec.expected_cap == crate::labels::Cap::JSON_PARSE {
+        return Ok(emit_json_parse_harness(spec));
+    }
+
     // Phase 19 (Track M.1): ClassMethod short-circuit.
     if let crate::evidence::EntryKind::ClassMethod { class, method } = &spec.entry_kind {
         return Ok(emit_class_method_harness(class, method));
@@ -1596,6 +1608,131 @@ _nyx_run
     }
 }
 
+/// Phase 11 (Track J.9) — JSON_PARSE depth-bomb harness for Ruby.
+///
+/// Rebinds `JSON.parse` to a depth-counting wrapper that calls the
+/// original parser, walks the resulting value iteratively (no
+/// recursion stack) to compute maximum nesting depth, emits a
+/// `ProbeKind::JsonParse { depth, excessive_depth }` record, then
+/// returns the parsed value verbatim.  `JSON::NestingError` raised by
+/// the Ruby json gem (default `max_nesting` is 100) is caught and
+/// converted into a `JsonParse { depth: 0, excessive_depth: true }`
+/// probe before the error is re-raised — matching the Python harness's
+/// `RecursionError` handling and the JS harness's `RangeError`
+/// handling.
+///
+/// Mirrors `crate::dynamic::lang::python::emit_json_parse_harness` and
+/// `crate::dynamic::lang::js_shared::emit_json_parse_harness`.
+pub fn emit_json_parse_harness(spec: &HarnessSpec) -> HarnessSource {
+    let shim = probe_shim();
+    let entry_basename = derive_entry_basename(&spec.entry_file);
+    let entry_name = if spec.entry_name.is_empty() {
+        "run".to_owned()
+    } else {
+        spec.entry_name.clone()
+    };
+    let body = format!(
+        r#"# Nyx dynamic harness — JSON_PARSE depth checks (Phase 11 / Track J.9).
+require 'json'
+
+{shim}
+
+NYX_MAX_WALK = 4096
+
+def _nyx_count_depth(parsed)
+  max_depth = 0
+  stack = [[parsed, 1]]
+  visited = 0
+  until stack.empty?
+    cur, depth = stack.pop
+    visited += 1
+    break if visited > NYX_MAX_WALK
+    max_depth = depth if depth > max_depth
+    case cur
+    when Hash
+      cur.each_value {{ |v| stack.push([v, depth + 1]) }}
+    when Array
+      cur.each {{ |v| stack.push([v, depth + 1]) }}
+    end
+  end
+  max_depth
+end
+
+def _nyx_json_parse_probe(depth, excessive)
+  p = ENV['NYX_PROBE_PATH']
+  return if p.nil? || p.empty?
+  rec = {{
+    'sink_callee'    => 'JSON.parse',
+    'args'           => [{{ 'kind' => 'Int', 'value' => depth.to_i }}],
+    'captured_at_ns' => Process.clock_gettime(Process::CLOCK_MONOTONIC, :nanosecond),
+    'payload_id'     => ENV['NYX_PAYLOAD_ID'] || '',
+    'kind'           => {{
+      'kind'            => 'JsonParse',
+      'depth'           => depth.to_i,
+      'excessive_depth' => !!excessive,
+    }},
+    'witness'        => __nyx_witness('JSON.parse', [depth.to_i]),
+  }}
+  begin
+    File.open(p, 'a') {{ |f| f.write(rec.to_json + "\n") }}
+  rescue StandardError
+    # best-effort
+  end
+end
+
+_nyx_orig_json_parse = JSON.method(:parse)
+
+JSON.define_singleton_method(:parse) do |source, *args, **opts|
+  begin
+    parsed = _nyx_orig_json_parse.call(source, *args, **opts)
+  rescue JSON::NestingError => e
+    # The json gem raises NestingError once `max_nesting` (default 100)
+    # is exceeded.  Emit the excessive-depth probe before re-raising so
+    # the oracle still fires when the parser rejects the input.
+    _nyx_json_parse_probe(0, true)
+    raise e
+  end
+  depth = _nyx_count_depth(parsed)
+  _nyx_json_parse_probe(depth, depth > 64)
+  parsed
+end
+
+def _nyx_json_parse_via_fixture(payload)
+  $LOAD_PATH.unshift('.')
+  begin
+    require_relative './{entry_basename}'
+  rescue LoadError, ScriptError => e
+    STDERR.puts("NYX_IMPORT_ERROR: #{{e.message}}")
+    exit 77
+  end
+  fn_sym = :'{entry_name}'
+  unless Object.respond_to?(fn_sym, true) || self.respond_to?(fn_sym, true)
+    return false
+  end
+  begin
+    send(fn_sym, payload)
+  rescue StandardError
+    # Parser errors / depth-induced raises are expected on the vuln
+    # payload; the probe is already emitted.
+  end
+  true
+end
+
+payload = ENV['NYX_PAYLOAD'] || ''
+_nyx_json_parse_via_fixture(payload)
+STDOUT.puts '__NYX_SINK_HIT__'
+STDOUT.flush
+"#
+    );
+    HarnessSource {
+        source: body,
+        filename: "harness.rb".to_owned(),
+        command: vec!["ruby".to_owned(), "harness.rb".to_owned()],
+        extra_files: vec![],
+        entry_subpath: None,
+    }
+}
+
 fn generate_source(spec: &HarnessSpec, shape: RubyShape) -> String {
     let entry_fn = &spec.entry_name;
     let pre_call = build_pre_call(spec);
@@ -2434,4 +2571,90 @@ mod tests {
         );
         let _ = std::fs::remove_dir_all(&dir);
     }
+
+    fn make_json_parse_spec(entry_file: &str, entry_name: &str) -> HarnessSpec {
+        let mut spec = make_spec(PayloadSlot::Param(0));
+        spec.expected_cap = Cap::JSON_PARSE;
+        spec.entry_file = entry_file.to_owned();
+        spec.entry_name = entry_name.to_owned();
+        spec
+    }
+
+    #[test]
+    fn emit_dispatches_to_json_parse_harness_when_cap_is_json_parse() {
+        let h = emit(&make_json_parse_spec(
+            "tests/dynamic_fixtures/json_parse_depth/ruby/vuln.rb",
+            "run",
+        ))
+        .unwrap();
+        assert!(
+            h.source.contains("JSON.define_singleton_method(:parse)"),
+            "dispatcher must select the JSON_PARSE depth harness: {}",
+            h.source
+        );
+        assert!(
+            h.source.contains("=> 'JsonParse'"),
+            "JSON_PARSE harness must emit JsonParse probes: {}",
+            h.source
+        );
+    }
+
+    #[test]
+    fn emit_json_parse_harness_monkey_patches_json_parse() {
+        let h = emit_json_parse_harness(&make_json_parse_spec(
+            "tests/dynamic_fixtures/json_parse_depth/ruby/vuln.rb",
+            "run",
+        ));
+        assert!(h.source.contains("_nyx_orig_json_parse = JSON.method(:parse)"));
+        assert!(
+            h.source.contains("JSON.define_singleton_method(:parse)"),
+            "must rebind JSON.parse: {}",
+            h.source
+        );
+        assert!(h.source.contains("def _nyx_count_depth(parsed)"));
+    }
+
+    #[test]
+    fn emit_json_parse_harness_emits_depth_fields() {
+        let h = emit_json_parse_harness(&make_json_parse_spec(
+            "tests/dynamic_fixtures/json_parse_depth/ruby/vuln.rb",
+            "run",
+        ));
+        assert!(h.source.contains("'depth'           => depth.to_i"));
+        assert!(h.source.contains("'excessive_depth' => !!excessive"));
+        assert!(h.source.contains("depth > 64"));
+        assert!(h.source.contains("__NYX_SINK_HIT__"));
+    }
+
+    #[test]
+    fn emit_json_parse_harness_handles_nesting_error() {
+        let h = emit_json_parse_harness(&make_json_parse_spec(
+            "tests/dynamic_fixtures/json_parse_depth/ruby/vuln.rb",
+            "run",
+        ));
+        assert!(h.source.contains("rescue JSON::NestingError => e"));
+        assert!(h.source.contains("_nyx_json_parse_probe(0, true)"));
+    }
+
+    #[test]
+    fn emit_json_parse_harness_routes_through_fixture_require() {
+        let h = emit_json_parse_harness(&make_json_parse_spec(
+            "tests/dynamic_fixtures/json_parse_depth/ruby/vuln.rb",
+            "run",
+        ));
+        assert!(
+            h.source
+                .contains("def _nyx_json_parse_via_fixture(payload)")
+        );
+        assert!(h.source.contains("require_relative './vuln'"));
+        assert!(h.source.contains("fn_sym = :'run'"));
+        assert_eq!(h.filename, "harness.rb");
+        assert!(h.extra_files.is_empty());
+    }
+
+    #[test]
+    fn emit_json_parse_harness_derives_entry_basename_from_entry_file() {
+        let h = emit_json_parse_harness(&make_json_parse_spec("/abs/path/benign.rb", "run"));
+        assert!(h.source.contains("require_relative './benign'"));
+    }
 }

tests/dynamic_fixtures/json_parse_depth/javascript/vuln.js

@@ -0,0 +1,23 @@
+// JavaScript JSON_PARSE depth-bomb vuln fixture.
+//
+// Models a config-driven JSON ingest endpoint that picks the parser
+// input based on the request payload tag — `*_DEEP` routes through a
+// deeply-nested array literal (256 levels) that drives `JSON.parse`
+// past the 64-level depth budget; `*_SHALLOW` routes through a flat
+// `[]` parse that leaves the predicate clear.  This shape is needed
+// by the differential runner: the vuln-payload attempt and the
+// benign-control attempt both load the same fixture, and only the
+// payload-routed deep branch trips the `JsonParseExcessiveDepth`
+// predicate.
+function run(value) {
+    const text = Buffer.isBuffer(value)
+        ? value.toString('utf8')
+        : String(value);
+    if (text.indexOf('DEEP') !== -1) {
+        const nested = '['.repeat(256) + ']'.repeat(256);
+        return JSON.parse(nested);
+    }
+    return JSON.parse('[]');
+}
+
+module.exports = { run };

tests/dynamic_fixtures/json_parse_depth/ruby/vuln.rb

@@ -0,0 +1,23 @@
+# Ruby JSON_PARSE depth-bomb vuln fixture.
+#
+# Models a config-driven JSON ingest endpoint that picks the parser
+# input based on the request payload tag — `*_DEEP` routes through a
+# deeply-nested array literal (256 levels) that drives `JSON.parse`
+# past the 64-level depth budget; `*_SHALLOW` routes through a flat
+# `[]` parse that leaves the predicate clear.  This shape is needed
+# by the differential runner: the vuln-payload attempt and the
+# benign-control attempt both load the same fixture, and only the
+# payload-routed deep branch trips the `JsonParseExcessiveDepth`
+# predicate.  `max_nesting: false` disables the json gem's depth
+# guard so the harness's depth walker sees the full 256-level shape
+# rather than triggering `JSON::NestingError` at depth 100.
+require 'json'
+
+def run(value)
+  text = value.to_s
+  if text.include?('DEEP')
+    nested = '[' * 256 + ']' * 256
+    return JSON.parse(nested, max_nesting: false)
+  end
+  JSON.parse('[]')
+end

tests/json_parse_corpus.rs

@@ -128,7 +128,9 @@ mod e2e_json_parse_depth {
             .join("tests/dynamic_fixtures/json_parse_depth")
             .join(match lang {
                 Lang::Python => "python",
-                _ => unreachable!("JSON_PARSE depth e2e covers Python only"),
+                Lang::JavaScript => "javascript",
+                Lang::Ruby => "ruby",
+                _ => unreachable!("JSON_PARSE depth e2e covers Python + JavaScript + Ruby only"),
             })
             .join(fixture);
         let tmp = TempDir::new().expect("create tempdir");
@@ -167,8 +169,14 @@ mod e2e_json_parse_depth {
     }
 
     fn run(lang: Lang, fixture: &str, entry_name: &str) -> Option<RunOutcome> {
-        if !command_available("python3") {
-            eprintln!("SKIP {lang:?} {fixture}: missing toolchain python3");
+        let required = match lang {
+            Lang::Python => "python3",
+            Lang::JavaScript => "node",
+            Lang::Ruby => "ruby",
+            _ => unreachable!("JSON_PARSE depth e2e covers Python + JavaScript + Ruby only"),
+        };
+        if !command_available(required) {
+            eprintln!("SKIP {lang:?} {fixture}: missing toolchain {required}");
             return None;
         }
         let _guard = FIXTURE_LOCK.lock().unwrap_or_else(|e| e.into_inner());
@@ -208,6 +216,22 @@ mod e2e_json_parse_depth {
         };
         assert_confirmed(Lang::Python, &outcome);
     }
+
+    #[test]
+    fn javascript_vuln_confirms_via_run_spec() {
+        let Some(outcome) = run(Lang::JavaScript, "vuln.js", "run") else {
+            return;
+        };
+        assert_confirmed(Lang::JavaScript, &outcome);
+    }
+
+    #[test]
+    fn ruby_vuln_confirms_via_run_spec() {
+        let Some(outcome) = run(Lang::Ruby, "vuln.rb", "run") else {
+            return;
+        };
+        assert_confirmed(Lang::Ruby, &outcome);
+    }
 }
 
 #[test]