refactor(traceability): parameterise the extractor for all three components

The tool is moving into the jray-project submodule to be shared by
scene-actor-extraction (C++/Python), jRay (C#) and JRay-public-server
(Rust). Two constants blocked that: LOCAL_TYPES and SOURCE_SUFFIXES were
hardcoded to this repo, so either sibling parsed zero requirements and
scanned zero files. Both, plus the register path, scan roots, system-spec
path, exclude list and CI-executable tier set, are now configuration.

One implementation, parameterised. A second copy for "the other language"
is how two implementations start drifting apart, so there is exactly one -
the same code path now produces:

  scene-actor-extraction  AR/DP/IR/GR/VR   59 defined   0 tagged    0.0%
  jRay                    JR               46 defined  24 covered  52.2%
  JRay-public-server      UR/DR            32 defined  23 covered  71.9%

Configuration is traceability.toml at the component repo root, CLI flags,
or both (flags win). Its directory defines the repo root, so the gate works
from any subdirectory. `--print-example-config` emits the annotated schema.
The JSON report echoes the settings it ran with, since a shared tool's
output is otherwise ambiguous about which repo it describes.

The refusal behaviour is kept and sharpened, because parameterising is
exactly what makes it easy to point a repo at the wrong prefixes or the
wrong suffixes. Zero requirements parsed or zero files scanned is still a
hard failure, and the message now names the setting that is wrong rather
than printing a plausible 0%. Config errors exit 2, not 1: a broken config
is not a coverage failure, and conflating them makes CI logs lie about why
the job went red.

Also fixed while adapting to the sibling registers, which are read but not
modified here:

  * escaped `\|` inside a markdown cell no longer shifts every later column
    (the server's register contains `small-\|M\|`);
  * a tag above an attribute-decorated declaration attributes to the
    declaration, not to `[HttpGet(...)]` or `#[derive(...)]` - the gap
    jRay's register calls out;
  * Rust and C# declaration patterns for context extraction;
  * the missing-tier warning is suppressed for a register that assigns no
    tiers at all, rather than listing every requirement in it.

The workflow is now component-agnostic too: the changed-file check reads
its extension list out of the report the gate just wrote, so the definition
of "source file" lives in one place.

79 tests, still fixture-based, now including the cross-repo cases: the same
parser over JR and UR/DR registers, the same scanner over Rust and C#, and
both misconfigurations failing loudly.

.gitea/workflows/traceability-check.yml

@@ -1,8 +1,13 @@
 name: Traceability Validation
 
-# Mirrors JellyTau's .gitea/workflows/traceability-check.yml, adapted for a
-# C++/Python repo: the extractor is Python and needs nothing but python3, so
-# there is no toolchain install step and no jq.
+# Mirrors JellyTau's .gitea/workflows/traceability-check.yml. The extractor is
+# stdlib Python, so there is no toolchain install step and no jq.
+#
+# This workflow is component-agnostic: every repo-specific setting - which ID
+# prefixes count, which file suffixes are source, which directories to scan,
+# the threshold - lives in traceability.toml at the repo root, and the same
+# extractor is shared by all three JRay components. Copying this file into
+# another component needs no edits.
 #
 # NOTE: the runner here is an Intel N100 with no discrete GPU. This job is only
 # ever static analysis of source comments plus markdown parsing, so it is cheap;
@@ -31,14 +36,15 @@ jobs:
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
+          submodules: recursive
 
       - name: Check Python is available
         run: |
           set -e
           command -v python3 >/dev/null 2>&1 || {
             echo "python3 is missing from the runner image."
-            echo "The traceability tooling is stdlib-only Python 3.9+;"
-            echo "no other dependency is needed."
+            echo "The traceability tooling is stdlib-only Python;"
+            echo "3.9+ with CLI flags, 3.11+ to read traceability.toml."
             exit 1
           }
           python3 --version
@@ -49,10 +55,13 @@ jobs:
       - name: Test the extractor
         run: python3 scripts/traceability/test_extract_traces.py
 
-      # Threshold policy lives in traceability-gate.sh, not here, so local runs
-      # and CI runs cannot disagree about what "passing" means. Denominators
-      # come from docs/requirements.md at run time and are never hardcoded --
-      # in this file or anywhere else.
+      # Threshold policy and every other repo-specific setting live in
+      # traceability.toml, not here, so local runs and CI runs cannot disagree
+      # about what "passing" means. Denominators come from docs/requirements.md
+      # at run time and are never hardcoded -- in this file or anywhere else.
+      #
+      # A misconfigured run (zero requirements parsed, zero files scanned) is a
+      # hard failure rather than a plausible-looking 0%.
       - name: Traceability gate
         run: sh scripts/traceability/traceability-gate.sh
 
@@ -62,11 +71,22 @@ jobs:
           set -e
           echo "Checking modified sources for TRACES tags..."
 
+          # The extensions come from the report the gate just wrote, which got
+          # them from traceability.toml. Restating them here would be a second
+          # place for the source-file definition to live, and the two would
+          # drift the first time a language is added.
+          PATTERN=$(python3 -c "
+          import json, re, sys
+          suffixes = json.load(open('traces-report.json'))['config']['sourceSuffixes']
+          print('(' + '|'.join(re.escape(s) + '\$' for s in suffixes) + ')')
+          ")
+          echo "Source suffixes from traceability.toml: $PATTERN"
+
           CHANGED=$(git diff --name-only "origin/${{ github.base_ref }}...HEAD" \
-                    | grep -E '\.(cpp|cc|cxx|hpp|hxx|h|cu|cuh|py)$' || true)
+                    | grep -E "$PATTERN" || true)
 
           if [ -z "$CHANGED" ]; then
-            echo "No C++/Python files changed."
+            echo "No source files changed."
             exit 0
           fi
 
@@ -85,7 +105,7 @@ jobs:
           MISSING=$(mktemp)
           echo "$CHANGED" | while IFS= read -r file; do
             case "$file" in
-              */test_*.py|*_test.py|tests/*|*/tests/*) continue ;;
+              */test_*.py|*_test.py|*Tests.cs|tests/*|*/tests/*) continue ;;
             esac
             [ -f "$file" ] || continue
             if ! grep -q 'TRACES:' "$file"; then

docs/traceability.md

@@ -1,11 +1,11 @@
 # Requirements traceability matrix
 
 <!-- GENERATED FILE - do not edit by hand. -->
-<!-- Regenerate: python3 scripts/traceability/extract_traces.py --format markdown --markdown-out docs/traceability.md -->
+<!-- Regenerate: scripts/traceability/traceability-gate.sh -->
 
-**Generated:** 2026-07-30T16:15:17+00:00
+**Generated:** 2026-07-30T16:35:36+00:00
 
-Denominators are read from [`requirements.md`](requirements.md) at run time, never hardcoded. Coverage counts a requirement only when it is tagged in source **and** has a verification tier this CI host can execute — CI is an Intel N100 with no discrete GPU.
+Denominators are read from [`requirements.md`](requirements.md) at run time, never hardcoded. Coverage counts a requirement only when it is tagged in source **and** has a verification tier this repo's CI host can execute (`T1, T2, T3, static`).
 
 ## Summary
 
@@ -18,7 +18,7 @@ Denominators are read from [`requirements.md`](requirements.md) at run time, nev
 | Requirements covered | 0 |
 | **Coverage** | **0.0%** (0/59) |
 | Coverage of CI-executable scope | 0.0% (0/50) |
-| Tagged but unexecuted in CI (T4/GPU) | 0 |
+| Tagged but unexecuted in CI | 0 |
 | Orphan tags | 0 |
 
 ### By type
@@ -34,7 +34,7 @@ Denominators are read from [`requirements.md`](requirements.md) at run time, nev
 
 ## Not executable in CI
 
-CI runs on an Intel N100 with no discrete GPU. These requirements have no verification tier that can run here, so a tag on them is evidence of *intent*, not of verification. They are never counted as covered.
+These requirements have no verification tier this repo's CI host can run, so a tag on them is evidence of *intent*, not of verification. They are never counted as covered.
 
 | ID | Tiers | Tagged in source | Requirement |
 |---|---|---|---|
@@ -62,7 +62,7 @@ _None._
 
 ## Recorded exceptions
 
-Deliberate, documented departures from an invariant (`EXCEPTION: AR-nnn <reason>`). Reported separately and never counted as coverage — an exception is a decision to be reviewed, not evidence a requirement is met.
+Deliberate, documented departures from an invariant (`EXCEPTION: XX-nnn <reason>`). Reported separately and never counted as coverage — an exception is a decision to be reviewed, not evidence a requirement is met.
 
 _None._
 

scripts/traceability/test_extract_traces.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-"""Tests for the traceability extractor and coverage gate.
+"""Tests for the shared traceability extractor and coverage gate.
 
 Run standalone (no third-party dependencies)::
 
@@ -9,26 +9,32 @@ or under pytest, which discovers the same functions::
 
     pytest scripts/traceability/test_extract_traces.py
 
-Almost every test runs over fixture strings rather than the live
-``docs/requirements.md``, so their meaning does not drift as requirements are
-added. The two properties they exist to pin are the ones JellyTau's gate lost
-(see JellyTau/docs/specs/traceability-gate-repair.md):
+Almost every test runs over fixture strings rather than any live
+``requirements.md``, so their meaning does not drift as requirements are added,
+and so they say the same thing in whichever component repo this tool is
+vendored into.
+
+Four properties these exist to pin:
 
 * the denominator is computed from the register at run time, so adding a
-  requirement lowers coverage until it is traced;
+  requirement lowers coverage until it is traced (JellyTau's gate lost this -
+  see JellyTau/docs/specs/traceability-gate-repair.md);
 * the numerator is an intersection, so a tag naming an undefined ID cannot push
-  the ratio above 100%.
-
-Plus the rule specific to this repo: a requirement only verifiable on GPU
-hardware is reported as tagged-but-unexecuted and never counted as covered.
+  the ratio above 100%;
+* a requirement whose only verification tier is outside what the CI host can
+  execute is reported as tagged-but-unexecuted, never counted as covered;
+* nothing about one repo is baked in - the same code parses the C++/Python,
+  C# and Rust components - and a misconfigured run refuses to report rather
+  than printing a plausible 0%.
 """
 
 from __future__ import annotations
 
 import io
+import json
 import sys
 import tempfile
-from contextlib import redirect_stdout
+from contextlib import redirect_stderr, redirect_stdout
 from pathlib import Path
 
 HERE = Path(__file__).resolve().parent
@@ -36,12 +42,125 @@ sys.path.insert(0, str(HERE))
 
 import extract_traces as et  # noqa: E402
 
-# The literal tag keyword is assembled at run time so that this file's fixtures
-# do not register as real traces when the extractor scans scripts/.
+# The literal tag keywords are assembled at run time so that this file's
+# fixtures do not register as real traces when the extractor scans scripts/.
 TAG = "TRA" + "CES:"
 EXC = "EXCEP" + "TION:"
 
 
+def cfg(**overrides) -> et.Config:
+    """A minimal valid config; overrides name whatever a test cares about."""
+    base = dict(requirement_types=("AR", "DP", "IR", "GR", "VR"),
+                source_suffixes=et.LANGUAGE_SUFFIXES["cpp"]
+                | et.LANGUAGE_SUFFIXES["python"],
+                source_roots=("src", "scripts"))
+    base.update(overrides)
+    return et.Config(**base)
+
+
+CPP_PY = cfg()
+
+
+# --------------------------------------------------------------------------
+# Configuration: the thing that makes one implementation serve three repos
+# --------------------------------------------------------------------------
+
+def test_config_rejects_an_empty_requirement_type_list():
+    # The prefix cannot be guessed, and guessing wrong means parsing zero
+    # requirements - the failure this whole class of check exists to prevent.
+    try:
+        cfg(requirement_types=()).validate()
+    except et.ConfigError as exc:
+        assert "requirement_types is empty" in str(exc)
+    else:
+        raise AssertionError("expected ConfigError")
+
+
+def test_config_rejects_a_prefix_that_is_not_two_uppercase_letters():
+    try:
+        cfg(requirement_types=("Jr",)).validate()
+    except et.ConfigError as exc:
+        assert "two-letter uppercase" in str(exc)
+    else:
+        raise AssertionError("expected ConfigError")
+
+
+def test_config_rejects_a_prefix_that_is_both_counted_and_excluded():
+    # A prefix cannot be in the fraction and out of it at once; silently
+    # picking one would make the reported number unexplainable.
+    try:
+        cfg(requirement_types=("UR", "UT")).validate()
+    except et.ConfigError as exc:
+        assert "cannot also be excluded" in str(exc)
+    else:
+        raise AssertionError("expected ConfigError")
+
+
+def test_config_rejects_empty_suffixes_and_roots():
+    for kwargs, expected in ((dict(source_suffixes=frozenset()), "no source suffixes"),
+                             (dict(source_roots=()), "no source roots")):
+        try:
+            cfg(**kwargs).validate()
+        except et.ConfigError as exc:
+            assert expected in str(exc)
+        else:
+            raise AssertionError(f"expected ConfigError for {kwargs}")
+
+
+def test_config_rejects_a_suffix_missing_its_dot():
+    try:
+        cfg(source_suffixes=frozenset({"rs"})).validate()
+    except et.ConfigError as exc:
+        assert "must start with a dot" in str(exc)
+    else:
+        raise AssertionError("expected ConfigError")
+
+
+def test_config_from_dict_expands_language_groups():
+    config = et.config_from_dict(
+        {"requirement_types": ["UR", "DR"], "languages": ["rust"],
+         "source_roots": ["src", "tests"]}, Path("/repo"), "fixture")
+    config.validate()
+    assert config.source_suffixes == frozenset({".rs"})
+    assert config.requirement_types == ("UR", "DR")
+
+
+def test_config_from_dict_rejects_an_unknown_key():
+    # A typo'd key would leave a required field empty, and the user would be
+    # debugging "zero requirements" instead of a misspelling.
+    try:
+        et.config_from_dict({"requirement_type": ["JR"]}, Path("/repo"), "fixture")
+    except et.ConfigError as exc:
+        assert "unknown key" in str(exc)
+    else:
+        raise AssertionError("expected ConfigError")
+
+
+def test_config_from_dict_rejects_an_unknown_language():
+    try:
+        et.config_from_dict({"languages": ["cobol"]}, Path("/repo"), "fixture")
+    except et.ConfigError as exc:
+        assert "unknown language" in str(exc)
+    else:
+        raise AssertionError("expected ConfigError")
+
+
+def test_example_config_is_itself_valid_and_complete():
+    # The documentation people copy must parse, or it teaches the wrong schema.
+    tomllib = __import__("tomllib")
+    data = tomllib.loads(et.example_config())
+    config = et.config_from_dict(data, Path("/repo"), "example")
+    config.validate()
+    assert config.requirement_types == ("AR", "DP", "IR", "GR", "VR")
+
+
+def test_config_paths_resolve_against_the_repo_root_not_the_cwd():
+    config = cfg(root=Path("/repo"), requirements_path="docs/requirements.md")
+    assert config.resolve("docs/requirements.md") == Path("/repo/docs/requirements.md")
+    assert config.resolve("/abs/spec.md") == Path("/abs/spec.md")
+    assert config.resolve(None) is None
+
+
 # --------------------------------------------------------------------------
 # Tag parsing
 # --------------------------------------------------------------------------
@@ -62,8 +181,8 @@ def test_parses_multiple_types_separated_by_pipe():
 
 
 def test_parses_three_groups_including_test_ids():
-    groups, _ = et.parse_traces_tag(" AR-012 | SR-002 | UT-003, UT-004")
-    assert groups == [["AR-012"], ["SR-002"], ["UT-003", "UT-004"]]
+    groups, _ = et.parse_traces_tag(" JR-012 | SR-002 | UT-003, UT-004")
+    assert groups == [["JR-012"], ["SR-002"], ["UT-003", "UT-004"]]
 
 
 def test_strips_a_trailing_block_comment_terminator():
@@ -94,7 +213,7 @@ def test_two_digit_id_is_not_accepted_as_a_requirement():
 
 
 # --------------------------------------------------------------------------
-# Scanning C++ and Python sources
+# Scanning: the same scanner over every component's language
 # --------------------------------------------------------------------------
 
 def _write_tree(root: Path) -> None:
@@ -126,26 +245,82 @@ def test_scans_cpp_and_python_but_not_vendored_or_non_source():
     with tempfile.TemporaryDirectory() as tmp:
         root = Path(tmp)
         _write_tree(root)
-        files = et.iter_source_files(root)
-        names = sorted(f.name for f in files)
-        assert names == ["gallery.py", "tracker.hpp"], names
+        config = cfg(root=root)
+        files = et.iter_source_files(config)
+        assert sorted(f.name for f in files) == ["gallery.py", "tracker.hpp"]
 
-        scan = et.scan_files(files, root)
+        scan = et.scan_files(files, config)
         traced = sorted({i for t in scan.traces for i in t.requirements})
         assert traced == ["AR-012", "AR-013", "GR-001", "SR-002", "SR-005"]
 
 
+def test_the_same_scanner_reads_rust_when_configured_for_it():
+    # JRay-public-server: Rust sources, UR/DR prefixes. No second extractor.
+    with tempfile.TemporaryDirectory() as tmp:
+        root = Path(tmp)
+        (root / "src").mkdir(parents=True)
+        (root / "src" / "manifest.rs").write_text(
+            f"/// {TAG} UR-002 | SR-004\n"
+            "pub fn accept_upload(body: Body) -> Response {\n"
+            "    todo!()\n"
+            "}\n", encoding="utf-8")
+        config = cfg(root=root, requirement_types=("UR", "DR"),
+                     source_suffixes=et.LANGUAGE_SUFFIXES["rust"],
+                     source_roots=("src",))
+        scan = et.scan_files(et.iter_source_files(config), config)
+        assert len(scan.traces) == 1
+        assert scan.traces[0].requirements == ["UR-002", "SR-004"]
+        assert "accept_upload" in scan.traces[0].context
+
+
+def test_the_same_scanner_reads_csharp_when_configured_for_it():
+    # jRay: C# plugin, JR prefix, and a tag above an attribute-decorated action.
+    with tempfile.TemporaryDirectory() as tmp:
+        root = Path(tmp)
+        (root / "Jellyfin.Plugin.JRay").mkdir(parents=True)
+        (root / "Jellyfin.Plugin.JRay" / "TruthController.cs").write_text(
+            f"    /// {TAG} JR-012 | SR-001\n"
+            '    [HttpGet("{itemId}")]\n'
+            "    public ActionResult<TruthFile> GetTruth(Guid itemId)\n"
+            "    {\n"
+            "        return Ok();\n"
+            "    }\n", encoding="utf-8")
+        config = cfg(root=root, requirement_types=("JR",),
+                     source_suffixes=et.LANGUAGE_SUFFIXES["csharp"],
+                     source_roots=("Jellyfin.Plugin.JRay",))
+        scan = et.scan_files(et.iter_source_files(config), config)
+        assert len(scan.traces) == 1
+        assert scan.traces[0].requirements == ["JR-012", "SR-001"]
+        # The attribute must not steal the context from the method it decorates.
+        assert "GetTruth" in scan.traces[0].context
+        assert "HttpGet" not in scan.traces[0].context
+
+
 def test_context_is_found_below_a_cpp_tag_and_above_a_python_tag():
     # The two languages put the tag on opposite sides of what it describes.
     with tempfile.TemporaryDirectory() as tmp:
         root = Path(tmp)
         _write_tree(root)
-        scan = et.scan_files(et.iter_source_files(root), root)
+        config = cfg(root=root)
+        scan = et.scan_files(et.iter_source_files(config), config)
         contexts = {t.file: t.context for t in scan.traces}
         assert "TrackRegistry" in contexts["src/tracker.hpp"]
         assert "build_gallery" in contexts["scripts/gallery.py"]
 
 
+def test_an_id_of_an_unconfigured_prefix_is_reported_as_unknown():
+    # In the Rust server, an `AR-001` tag is a copy-paste from another repo.
+    with tempfile.TemporaryDirectory() as tmp:
+        root = Path(tmp)
+        (root / "src").mkdir(parents=True)
+        (root / "src" / "a.rs").write_text(f"// {TAG} AR-001\n", encoding="utf-8")
+        config = cfg(root=root, requirement_types=("UR", "DR"),
+                     source_suffixes=et.LANGUAGE_SUFFIXES["rust"],
+                     source_roots=("src",))
+        scan = et.scan_files(et.iter_source_files(config), config)
+        assert scan.diagnostics.unknown_id_types
+
+
 # --------------------------------------------------------------------------
 # EXCEPTION tags
 # --------------------------------------------------------------------------
@@ -158,12 +333,17 @@ EXCEPTION_SOURCE = (
 )
 
 
+def _exception_repo(tmp: str) -> et.Config:
+    root = Path(tmp)
+    (root / "src").mkdir(parents=True)
+    (root / "src" / "outlier.cpp").write_text(EXCEPTION_SOURCE, encoding="utf-8")
+    return cfg(root=root)
+
+
 def test_exception_tag_is_captured_with_its_reason():
     with tempfile.TemporaryDirectory() as tmp:
-        root = Path(tmp)
-        (root / "src").mkdir(parents=True)
-        (root / "src" / "outlier.cpp").write_text(EXCEPTION_SOURCE, encoding="utf-8")
-        scan = et.scan_files(et.iter_source_files(root), root)
+        config = _exception_repo(tmp)
+        scan = et.scan_files(et.iter_source_files(config), config)
         assert len(scan.exceptions) == 1
         exc = scan.exceptions[0]
         assert exc.requirement == "AR-024"
@@ -175,14 +355,12 @@ def test_exception_is_never_counted_as_coverage():
     # An exception is a recorded decision to depart from an invariant. Counting
     # it as evidence the requirement is met inverts its meaning.
     with tempfile.TemporaryDirectory() as tmp:
-        root = Path(tmp)
-        (root / "src").mkdir(parents=True)
-        (root / "src" / "outlier.cpp").write_text(EXCEPTION_SOURCE, encoding="utf-8")
-        scan = et.scan_files(et.iter_source_files(root), root)
+        config = _exception_repo(tmp)
+        scan = et.scan_files(et.iter_source_files(config), config)
         assert scan.traces == []
         register = et.parse_register(
             "| ID | Requirement | Status |\n|---|---|---|\n"
-            "| AR-024 | Always the calibrated probability | Planned |\n")
+            "| AR-024 | Always the calibrated probability | Planned |\n", config)
         cov = et.compute_coverage(
             [i for t in scan.traces for i in t.requirements], register)
         assert cov.covered == []
@@ -190,13 +368,13 @@ def test_exception_is_never_counted_as_coverage():
 
 
 def test_exception_without_a_reason_is_reported():
-    # CLAUDE.md: an exception is only *agreed* if the reason is recorded.
+    # An exception is only *agreed* if the reason is recorded.
     with tempfile.TemporaryDirectory() as tmp:
         root = Path(tmp)
         (root / "src").mkdir(parents=True)
-        (root / "src" / "bare.cpp").write_text(
-            f"// {EXC} AR-024\n", encoding="utf-8")
-        scan = et.scan_files(et.iter_source_files(root), root)
+        (root / "src" / "bare.cpp").write_text(f"// {EXC} AR-024\n", encoding="utf-8")
+        config = cfg(root=root)
+        scan = et.scan_files(et.iter_source_files(config), config)
         assert len(scan.exceptions) == 1
         assert scan.diagnostics.exceptions_without_reason
 
@@ -209,7 +387,8 @@ def test_mixed_type_group_is_reported():
         (root / "src").mkdir(parents=True)
         (root / "src" / "a.cpp").write_text(
             f"// {TAG} AR-001, SR-002\n", encoding="utf-8")
-        scan = et.scan_files(et.iter_source_files(root), root)
+        config = cfg(root=root)
+        scan = et.scan_files(et.iter_source_files(config), config)
         assert scan.diagnostics.mixed_type_groups
 
 
@@ -224,20 +403,41 @@ def test_counts_a_well_formed_table_row_as_a_defined_requirement():
     md = REGISTER_HEADER + (
         "| AR-001 | Detect faces in sampled frames | SR-002 | High | Done |\n"
         "| AR-002 | Minimum face size 66x66 px | SR-002 | High | Planned |\n")
-    register = et.parse_register(md)
+    register = et.parse_register(md, CPP_PY)
     assert register.count("AR") == 2
     assert register.count("GR") == 0
     assert register.total == 2
 
 
+def test_the_same_parser_reads_another_repos_prefixes():
+    # Identical table shape, different prefixes. This is the change that made
+    # the tool shareable: with requirement_types hardcoded, both of these
+    # parsed to zero.
+    md = REGISTER_HEADER + (
+        "| JR-001 | Truth-file schema | SR-003 | High | Done |\n"
+        "| UR-001 | Availability without payload | SR-001 | High | Done |\n"
+        "| DR-003 | One writer connection plus a read pool | SR-001 | High | Done |\n")
+    jray = et.parse_register(md, cfg(requirement_types=("JR",)))
+    server = et.parse_register(md, cfg(requirement_types=("UR", "DR")))
+    assert jray.ids == {"JR-001"}
+    assert server.ids == {"UR-001", "DR-003"}
+
+
+def test_a_prefix_this_repo_does_not_define_is_not_counted_as_defined():
+    # The server's register must not acquire a denominator from an AR row
+    # pasted in from the extraction repo.
+    md = REGISTER_HEADER + "| AR-001 | Belongs to another repo | SR-002 | High | Done |\n"
+    register = et.parse_register(md, cfg(requirement_types=("UR", "DR")))
+    assert register.total == 0
+
+
 def test_does_not_count_ids_that_appear_only_in_the_traces_to_column():
     # The bug this parse rule avoids: a naive scan for AR-\d{3} over the whole
     # file counts every reference as a definition and inflates the denominator.
     md = REGISTER_HEADER + (
         "| GR-001 | Build gallery from library cast | SR-001, SR-005 | High | Done |\n"
         "| GR-002 | Incremental merge refresh | PR-003 | High | Done |\n")
-    register = et.parse_register(md)
-    assert register.count("GR") == 2
+    register = et.parse_register(md, CPP_PY)
     assert register.ids == {"GR-001", "GR-002"}
 
 
@@ -245,7 +445,7 @@ def test_does_not_count_ids_mentioned_in_prose():
     md = ("Some prose explaining that AR-005 relates to GR-001 and VR-003.\n\n"
           + REGISTER_HEADER
           + "| AR-005 | Align to 112x112 | SR-002 | High | Done |\n")
-    register = et.parse_register(md)
+    register = et.parse_register(md, CPP_PY)
     assert register.ids == {"AR-005"}
 
 
@@ -259,9 +459,8 @@ def test_does_not_count_the_verification_plan_table_as_definitions():
           + "| ID | Tier | Test asserts | Edge cases to cover |\n|---|---|---|---|\n"
           + "| AR-001 | T3 | Detector returns plausible boxes | smoke only |\n"
           + "| AR-099 | T1 | Something not in the register | - |\n")
-    register = et.parse_register(md)
+    register = et.parse_register(md, CPP_PY)
     assert register.ids == {"AR-001"}
-    assert register.total == 1
 
 
 def test_deduplicates_an_id_listed_in_two_definition_tables():
@@ -270,8 +469,7 @@ def test_deduplicates_an_id_listed_in_two_definition_tables():
           + "\n"
           + REGISTER_HEADER
           + "| AR-001 | Detect faces | SR-002 | High | Done |\n")
-    register = et.parse_register(md)
-    assert register.total == 1
+    assert et.parse_register(md, CPP_PY).total == 1
 
 
 def test_withdrawn_requirements_leave_the_denominator():
@@ -280,18 +478,29 @@ def test_withdrawn_requirements_leave_the_denominator():
     md = REGISTER_HEADER + (
         "| AR-001 | Detect faces | SR-002 | High | Done |\n"
         "| AR-002 | Superseded mechanism | SR-002 | High | Withdrawn |\n")
-    register = et.parse_register(md)
+    register = et.parse_register(md, CPP_PY)
     assert register.ids == {"AR-001"}
     assert "AR-002" in register.withdrawn
 
 
+def test_an_escaped_pipe_inside_a_cell_does_not_split_the_row():
+    # The server's register contains `small-\|M\| all-but-one rule`; a naive
+    # split shifts every later column by one.
+    md = REGISTER_HEADER + (
+        r"| UR-003 | Strict schema with a small-\|M\| rule | SR-001 | High | Done |"
+        "\n")
+    register = et.parse_register(md, cfg(requirement_types=("UR",)))
+    assert register.requirements["UR-003"].status == "Done"
+    assert "|M|" in register.requirements["UR-003"].text
+
+
 def test_the_denominator_is_live_adding_a_row_lowers_coverage():
     # The property JellyTau's frozen literals destroyed. Same traced set, one
     # more requirement defined => a lower percentage, mechanically.
     base = REGISTER_HEADER + "| AR-001 | A | SR-002 | High | Done |\n"
     grown = base + "| AR-002 | B | SR-002 | High | Planned |\n"
-    before = et.compute_coverage(["AR-001"], et.parse_register(base))
-    after = et.compute_coverage(["AR-001"], et.parse_register(grown))
+    before = et.compute_coverage(["AR-001"], et.parse_register(base, CPP_PY))
+    after = et.compute_coverage(["AR-001"], et.parse_register(grown, CPP_PY))
     assert before.percent == 100.0
     assert after.percent == 50.0
     assert after.total == 2
@@ -300,14 +509,26 @@ def test_the_denominator_is_live_adding_a_row_lowers_coverage():
 def test_register_captures_the_row_fields_not_just_the_id():
     md = REGISTER_HEADER + (
         "| AR-012 | Presence follows track extent | **SR-002** | High | Planned |\n")
-    req = et.parse_register(md).requirements["AR-012"]
+    req = et.parse_register(md, CPP_PY).requirements["AR-012"]
     assert req.text == "Presence follows track extent"
     assert req.traces_to == "**SR-002**"
     assert req.status == "Planned"
 
 
+def test_a_requirement_tracing_up_to_nothing_is_reported():
+    # SPEC.md section 6: a requirement citing no parent is scope creep, and it
+    # is invisible unless something looks. A section reference counts as a
+    # parent - what matters is that something was recorded.
+    md = REGISTER_HEADER + (
+        "| AR-001 | Has a parent | SR-002 | High | Done |\n"
+        "| AR-002 | Parent is a section | §4 | Medium | Planned |\n"
+        "| AR-003 | Serves nothing stated | - | Low | Planned |\n"
+        "| AR-004 | Blank cell |  | Low | Planned |\n")
+    assert et.parse_register(md, CPP_PY).parentless_ids() == {"AR-003", "AR-004"}
+
+
 # --------------------------------------------------------------------------
-# Verification tiers and the GPU-less CI host
+# Verification tiers and the CI host's limits
 # --------------------------------------------------------------------------
 
 TIER_REGISTER = REGISTER_HEADER + "".join(
@@ -327,7 +548,7 @@ def test_tier_assignment_handles_lists_ranges_and_wildcards():
         "| AR-002 … AR-004 | **T2** | replay |\n"
         "| AR-006 | T1 + T4 | mixed |\n"
         "| VR-* | Out of CI | studies |\n")
-    register = et.parse_register(md)
+    register = et.parse_register(md, CPP_PY)
     assert register.requirements["AR-001"].tiers == {"T3"}
     assert register.requirements["AR-003"].tiers == {"T2"}
     assert register.requirements["AR-006"].tiers == {"T1", "T4"}
@@ -336,7 +557,7 @@ def test_tier_assignment_handles_lists_ranges_and_wildcards():
 
 def test_a_range_cannot_invent_a_requirement_the_register_lacks():
     md = TIER_REGISTER + "\n" + _tier_table("| AR-001 … AR-050 | T2 | wide |\n")
-    register = et.parse_register(md)
+    register = et.parse_register(md, CPP_PY)
     assert register.total == 12
     assert "AR-050" not in register.ids
 
@@ -345,7 +566,7 @@ def test_slash_shorthand_in_the_verification_plan_expands():
     md = TIER_REGISTER + "\n" + (
         "| ID | Tier | Test asserts | Edge cases |\n|---|---|---|---|\n"
         "| AR-009/008 | T2 | Cut shifts weighting | cut with same people |\n")
-    register = et.parse_register(md)
+    register = et.parse_register(md, CPP_PY)
     assert register.requirements["AR-008"].tiers == {"T2"}
     assert register.requirements["AR-009"].tiers == {"T2"}
 
@@ -357,35 +578,43 @@ def test_tiers_from_both_tables_are_unioned_not_overwritten():
     md = TIER_REGISTER + "\n" + _tier_table("| AR-006 | T4 | GPU host only |\n") + "\n" + (
         "| ID | Tier | Test asserts | Edge cases |\n|---|---|---|---|\n"
         "| AR-006 | T1 + T4 | GEMM equals reference loop | small input in CI |\n")
-    register = et.parse_register(md)
+    register = et.parse_register(md, CPP_PY)
     assert register.requirements["AR-006"].tiers == {"T1", "T4"}
-    assert register.requirements["AR-006"].ci_executable
+    assert register.is_ci_executable("AR-006")
 
 
 def test_a_t4_only_requirement_is_not_ci_executable():
     md = TIER_REGISTER + "\n" + _tier_table("| AR-007 | **T4** | GPU only |\n")
-    register = et.parse_register(md)
-    assert not register.requirements["AR-007"].ci_executable
+    register = et.parse_register(md, CPP_PY)
+    assert not register.is_ci_executable("AR-007")
     assert register.unexecutable_ids() == {"AR-007"}
 
 
-def test_a_requirement_tracing_up_to_nothing_is_reported():
-    # SPEC.md section 6: a requirement citing no parent is scope creep, and it
-    # is invisible unless something looks. A section reference counts as a
-    # parent - what matters is that something was recorded.
-    md = REGISTER_HEADER + (
-        "| AR-001 | Has a parent | SR-002 | High | Done |\n"
-        "| AR-002 | Parent is a section | §4 | Medium | Planned |\n"
-        "| AR-003 | Serves nothing stated | - | Low | Planned |\n"
-        "| AR-004 | Blank cell |  | Low | Planned |\n")
-    register = et.parse_register(md)
-    assert register.parentless_ids() == {"AR-003", "AR-004"}
+def test_which_tiers_count_as_executable_is_configuration_not_code():
+    # A repo whose CI host can run T4 says so, and the same register then
+    # yields full executability. Nothing about one host is baked in.
+    md = TIER_REGISTER + "\n" + _tier_table("| AR-007 | **T4** | GPU only |\n")
+    permissive = et.parse_register(
+        md, cfg(ci_executable_tiers=frozenset({"T1", "T2", "T3", "T4", "static"})))
+    assert permissive.unexecutable_ids() == set()
+    assert permissive.is_ci_executable("AR-007")
 
 
 def test_a_requirement_with_no_tier_is_unknown_not_unexecutable():
-    register = et.parse_register(TIER_REGISTER)
+    register = et.parse_register(TIER_REGISTER, CPP_PY)
     assert register.tier_unknown_ids() == register.ids
     assert register.unexecutable_ids() == set()
+    assert not register.uses_tiers
+
+
+def test_a_register_that_uses_tiers_is_distinguishable_from_one_that_does_not():
+    # The distinction drives whether "no tier recorded" is worth warning about;
+    # warning on every requirement of a tierless register trains people to
+    # ignore the warning.
+    tiered = et.parse_register(
+        TIER_REGISTER + "\n" + _tier_table("| AR-001 | T1 | unit |\n"), CPP_PY)
+    assert tiered.uses_tiers
+    assert not et.parse_register(TIER_REGISTER, CPP_PY).uses_tiers
 
 
 # --------------------------------------------------------------------------
@@ -401,7 +630,8 @@ COVERAGE_REGISTER = et.parse_register(
     + "\n"
     + _tier_table("| AR-001, AR-002 | T2 | replay |\n"
                   "| GR-001 | T1 | bookkeeping |\n"
-                  "| AR-027 | **T4** | GPU host only |\n"))
+                  "| AR-027 | **T4** | GPU host only |\n"),
+    CPP_PY)
 
 
 def test_coverage_is_the_intersection_of_traced_and_defined():
@@ -425,14 +655,13 @@ def test_orphan_tags_are_reported_so_they_get_fixed():
 
 
 def test_no_orphans_when_every_traced_id_is_defined():
-    cov = et.compute_coverage(["AR-001", "AR-002"], COVERAGE_REGISTER)
-    assert cov.orphaned == []
+    assert et.compute_coverage(["AR-001", "AR-002"], COVERAGE_REGISTER).orphaned == []
 
 
 def test_test_and_system_ids_are_a_separate_taxonomy():
-    # UT/IT live in their own register section; PR/SR live in the umbrella
-    # SPEC.md, which is not part of this repo's checkout. Neither counts toward
-    # coverage, and flagging them as orphans would bury real typos in noise.
+    # UT/IT are evidence for requirements; PR/SR live in the system spec, which
+    # is a different register. Neither counts toward coverage, and flagging
+    # them as orphans would bury real typos in noise.
     cov = et.compute_coverage(
         ["AR-001", "UT-003", "IT-007", "SR-002", "PR-001"], COVERAGE_REGISTER)
     assert cov.orphaned == []
@@ -440,9 +669,8 @@ def test_test_and_system_ids_are_a_separate_taxonomy():
 
 
 def test_a_gpu_only_requirement_is_tagged_but_unexecuted_not_covered():
-    # The rule specific to this repo: CI is an Intel N100 with no dGPU. A test
-    # that exists but can never run is not evidence, and counting it is the
-    # same failure mode as the 158% bug.
+    # A test that exists but can never run on the CI host is not evidence, and
+    # counting it is the same failure mode as the 158% bug.
     cov = et.compute_coverage(["AR-001", "AR-027"], COVERAGE_REGISTER)
     assert cov.unexecuted == ["AR-027"]
     assert cov.covered == ["AR-001"]
@@ -475,7 +703,7 @@ def test_an_empty_trace_set_is_zero_percent_not_a_divide_by_zero():
 
 
 def test_an_empty_register_reports_zero_rather_than_nan():
-    cov = et.compute_coverage(["AR-001"], et.Register())
+    cov = et.compute_coverage(["AR-001"], et.Register(types=("AR",)))
     assert cov.percent == 0.0
     assert cov.ci_percent == 0.0
 
@@ -486,7 +714,6 @@ def test_full_coverage_reports_exactly_one_hundred_never_above():
     # AR-027 is GPU-only, so the honest ceiling here is 3/4.
     assert cov.percent == 75.0
     assert cov.ci_percent == 100.0
-    assert cov.ci_percent <= 100.0
 
 
 # --------------------------------------------------------------------------
@@ -502,23 +729,52 @@ FIXTURE_REGISTER = (
     + _tier_table("| AR-001, AR-002 | T2 | replay |\n"
                   "| AR-027 | **T4** | GPU host only |\n"))
 
+FIXTURE_CONFIG_TOML = """\
+requirement_types = ["AR"]
+languages = ["cpp"]
+source_roots = ["src"]
+"""
 
-def _fixture_repo(tmp: str, source: str) -> Path:
+
+def _fixture_repo(tmp: str, source: str, config_toml: str = FIXTURE_CONFIG_TOML,
+                  register: str = FIXTURE_REGISTER) -> Path:
     root = Path(tmp)
     (root / "docs").mkdir(parents=True, exist_ok=True)
     (root / "src").mkdir(parents=True, exist_ok=True)
-    (root / "docs" / "requirements.md").write_text(FIXTURE_REGISTER, encoding="utf-8")
+    (root / "docs" / "requirements.md").write_text(register, encoding="utf-8")
     (root / "src" / "pipeline.cpp").write_text(source, encoding="utf-8")
+    (root / et.CONFIG_FILENAME).write_text(config_toml, encoding="utf-8")
     return root
 
 
 def _run_gate(root: Path, *extra: str):
     buffer = io.StringIO()
     with redirect_stdout(buffer):
-        code = et.main(["--root", str(root), "--format", "coverage", *extra])
+        code = et.main(["--config", str(root / et.CONFIG_FILENAME),
+                        "--format", "coverage", *extra])
     return code, buffer.getvalue()
 
 
+def test_gate_reads_its_settings_from_the_repos_config_file():
+    with tempfile.TemporaryDirectory() as tmp:
+        root = _fixture_repo(tmp, f"// {TAG} AR-001\nint main() {{}}\n")
+        code, out = _run_gate(root)
+        assert code == 0, out
+        assert "Requirement types    : AR" in out
+        assert str(root / et.CONFIG_FILENAME) in out
+
+
+def test_config_is_discovered_from_a_subdirectory():
+    # The config file's directory is the repo root, so running the gate from
+    # deep inside the tree does not silently scan a subtree.
+    with tempfile.TemporaryDirectory() as tmp:
+        root = _fixture_repo(tmp, f"// {TAG} AR-001\nint main() {{}}\n")
+        nested = root / "src" / "nodes"
+        nested.mkdir(parents=True, exist_ok=True)
+        found = et.find_config(nested)
+        assert found == root / et.CONFIG_FILENAME
+
+
 def test_gate_passes_at_the_default_threshold_with_no_tags_yet():
     # Near-zero coverage on a fresh tree is the correct reading, not a failure.
     with tempfile.TemporaryDirectory() as tmp:
@@ -559,20 +815,48 @@ def test_gate_fails_when_the_register_parses_to_nothing():
     # With a low threshold this self-check is what keeps the gate meaningful:
     # a broken parser would otherwise report 0/0 and pass.
     with tempfile.TemporaryDirectory() as tmp:
-        root = _fixture_repo(tmp, "int main() {}\n")
-        (root / "docs" / "requirements.md").write_text(
-            "# register\n\nNo tables here.\n", encoding="utf-8")
+        root = _fixture_repo(tmp, "int main() {}\n",
+                             register="# register\n\nNo tables here.\n")
         code, out = _run_gate(root)
         assert code == 1
         assert "ZERO requirements" in out
 
 
-def test_gate_fails_when_no_source_files_were_scanned():
+def test_gate_fails_when_the_prefixes_are_configured_wrong():
+    # The misconfiguration a shared tool invites: the server's config pointed
+    # at the extraction register, or a typo'd prefix. Every row is skipped, and
+    # a plausible 0% would hide it completely.
     with tempfile.TemporaryDirectory() as tmp:
-        root = Path(tmp)
-        (root / "docs").mkdir(parents=True)
-        (root / "docs" / "requirements.md").write_text(FIXTURE_REGISTER,
-                                                       encoding="utf-8")
+        root = _fixture_repo(
+            tmp, f"// {TAG} AR-001\nint main() {{}}\n",
+            config_toml='requirement_types = ["JR"]\nlanguages = ["cpp"]\n'
+                        'source_roots = ["src"]\n')
+        code, out = _run_gate(root)
+        assert code == 1
+        assert "ZERO requirements" in out
+        assert "requirement_types (JR)" in out
+
+
+def test_gate_fails_when_the_suffixes_are_configured_wrong():
+    # The Rust config applied to a C++ repo: nothing to scan, and coverage
+    # against an empty tree means nothing.
+    with tempfile.TemporaryDirectory() as tmp:
+        root = _fixture_repo(
+            tmp, f"// {TAG} AR-001\nint main() {{}}\n",
+            config_toml='requirement_types = ["AR"]\nlanguages = ["rust"]\n'
+                        'source_roots = ["src"]\n')
+        code, out = _run_gate(root)
+        assert code == 1
+        assert "no source files were scanned" in out
+        assert ".rs" in out
+
+
+def test_gate_fails_when_the_source_roots_do_not_exist():
+    with tempfile.TemporaryDirectory() as tmp:
+        root = _fixture_repo(
+            tmp, f"// {TAG} AR-001\nint main() {{}}\n",
+            config_toml='requirement_types = ["AR"]\nlanguages = ["cpp"]\n'
+                        'source_roots = ["nowhere"]\n')
         code, out = _run_gate(root)
         assert code == 1
         assert "no source files were scanned" in out
@@ -594,11 +878,14 @@ def test_gate_hard_fails_on_an_impossible_ratio():
     # reported as a pass. Forced here by handing the reporter a poisoned value.
     with tempfile.TemporaryDirectory() as tmp:
         root = _fixture_repo(tmp, f"// {TAG} AR-001\nint main() {{}}\n")
-        register = et.read_register(root / "docs" / "requirements.md")
-        scan = et.scan_files(et.iter_source_files(root), root)
-        report = et.build_report(root, register, scan)
+        config = et.config_from_dict(
+            {"requirement_types": ["AR"], "languages": ["cpp"],
+             "source_roots": ["src"]}, root, "fixture")
+        register = et.read_register(config)
+        scan = et.scan_files(et.iter_source_files(config), config)
+        report = et.build_report(config, register, scan)
         report.coverage.percent = 158.0
-        text, code = et.format_coverage_report(report, 50.0)
+        text, code = et.format_coverage_report(report)
         assert code == 1
         assert "exceeds 100%" in text
 
@@ -607,11 +894,13 @@ def test_the_per_type_breakdown_sums_to_the_headline_figure():
     # A breakdown that does not add up to its own total is how a wrong number
     # survives review: every row looks plausible on its own.
     with tempfile.TemporaryDirectory() as tmp:
-        root = _fixture_repo(
-            tmp, f"// {TAG} AR-001, AR-027\nint main() {{}}\n")
-        register = et.read_register(root / "docs" / "requirements.md")
-        scan = et.scan_files(et.iter_source_files(root), root)
-        report = et.build_report(root, register, scan)
+        root = _fixture_repo(tmp, f"// {TAG} AR-001, AR-027\nint main() {{}}\n")
+        config = et.config_from_dict(
+            {"requirement_types": ["AR"], "languages": ["cpp"],
+             "source_roots": ["src"]}, root, "fixture")
+        register = et.read_register(config)
+        scan = et.scan_files(et.iter_source_files(config), config)
+        report = et.build_report(config, register, scan)
         stats = et.per_type_stats(report)
         assert sum(c for c, _, _ in stats.values()) == len(report.coverage.covered)
         assert sum(u for _, u, _ in stats.values()) == len(report.coverage.unexecuted)
@@ -620,64 +909,116 @@ def test_the_per_type_breakdown_sums_to_the_headline_figure():
 
 
 def test_json_and_markdown_outputs_are_written_and_consistent():
-    import json
     with tempfile.TemporaryDirectory() as tmp:
         root = _fixture_repo(tmp, f"// {TAG} AR-001 | SR-002\nint main() {{}}\n")
-        json_out = root / "traces-report.json"
-        md_out = root / "docs" / "traceability.md"
-        buffer = io.StringIO()
-        with redirect_stdout(buffer):
-            code = et.main(["--root", str(root), "--format", "coverage",
-                            "--json-out", str(json_out),
-                            "--markdown-out", str(md_out)])
+        code, _ = _run_gate(root)
         assert code == 0
-        data = json.loads(json_out.read_text(encoding="utf-8"))
+        data = json.loads((root / "traces-report.json").read_text(encoding="utf-8"))
         assert data["defined"]["total"] == 3
         assert data["coverage"]["covered"] == 1
         assert data["coverage"]["percent"] == round(100 / 3, 1)
         assert data["byType"]["SR"] == ["SR-002"]
-        assert data["gpuOnlyRequirements"] == ["AR-027"]
-        assert "AR-001" in md_out.read_text(encoding="utf-8")
+        assert data["unexecutableRequirements"] == ["AR-027"]
+        # The report says how it was produced; a shared tool's output is
+        # otherwise ambiguous about which repo and settings it describes.
+        assert data["config"]["requirementTypes"] == ["AR"]
+        assert data["config"]["sourceRoots"] == ["src"]
+        assert "AR-001" in (root / "docs" / "traceability.md").read_text(
+            encoding="utf-8")
+
+
+def test_cli_flags_alone_work_with_no_config_file_at_all():
+    # The path a repo takes before it has a traceability.toml, and the escape
+    # hatch on a Python too old for tomllib.
+    with tempfile.TemporaryDirectory() as tmp:
+        root = _fixture_repo(tmp, f"// {TAG} AR-001\nint main() {{}}\n")
+        (root / et.CONFIG_FILENAME).unlink()
+        buffer = io.StringIO()
+        with redirect_stdout(buffer):
+            code = et.main(["--no-config", "--root", str(root),
+                            "--requirement-type", "AR",
+                            "--language", "cpp", "--source-root", "src",
+                            "--format", "coverage", "--no-write"])
+        assert code == 0, buffer.getvalue()
+        assert "1 / 3" in buffer.getvalue()
+        assert not (root / "traces-report.json").exists()
+
+
+def test_cli_flags_override_the_config_file():
+    with tempfile.TemporaryDirectory() as tmp:
+        root = _fixture_repo(tmp, f"// {TAG} AR-001\nint main() {{}}\n")
+        code, out = _run_gate(root, "--requirement-type", "JR", "--no-write")
+        assert code == 1
+        assert "requirement_types (JR)" in out
+
+
+def test_language_flags_extend_rather_than_replace_the_configured_set():
+    with tempfile.TemporaryDirectory() as tmp:
+        root = _fixture_repo(tmp, f"// {TAG} AR-001\nint main() {{}}\n")
+        (root / "src" / "extra.rs").write_text(
+            f"/// {TAG} AR-002\npub fn go() {{}}\n", encoding="utf-8")
+        code, out = _run_gate(root, "--language", "rust", "--no-write")
+        assert code == 0, out
+        assert "2 / 3" in out
+
+
+def test_an_invalid_configuration_is_a_distinct_exit_code():
+    # 2, not 1: a broken config is not a coverage failure, and conflating them
+    # makes CI logs lie about why the job went red.
+    with tempfile.TemporaryDirectory() as tmp:
+        root = _fixture_repo(tmp, "int main() {}\n",
+                             config_toml='languages = ["cpp"]\nsource_roots = ["src"]\n')
+        buffer = io.StringIO()
+        with redirect_stdout(buffer), redirect_stderr(buffer):
+            code = et.main(["--config", str(root / et.CONFIG_FILENAME)])
+        assert code == 2
+        assert "requirement_types is empty" in buffer.getvalue()
 
 
 def test_system_spec_parsing_enables_orphan_checks_for_pr_and_sr():
     spec = ("### SR-002 - Presence is scene-scoped\n\n"
             "| ID | Goal | Why |\n|---|---|---|\n"
             "| **PR-001** | Show which actors are on screen | The product |\n")
-    ids = et.parse_system_spec(spec)
-    assert ids == {"SR-002", "PR-001"}
+    assert et.parse_system_spec(spec) == {"SR-002", "PR-001"}
 
     with tempfile.TemporaryDirectory() as tmp:
         root = _fixture_repo(tmp, f"// {TAG} AR-001 | SR-999\nint main() {{}}\n")
         spec_path = root / "system-spec.md"
         spec_path.write_text(spec, encoding="utf-8")
-        code, out = _run_gate(root, "--system-spec", str(spec_path))
+        code, out = _run_gate(root, "--system-spec", str(spec_path), "--no-write")
         assert "SR-999" in out
         assert code == 0  # advisory: the system register is not this repo's
 
 
 # --------------------------------------------------------------------------
-# The live register — structural assertions only, so this does not churn as
-# requirements are added.
+# The live repo — structural assertions only, so this does not churn as
+# requirements are added, and so it still means something once this file is
+# vendored into another component.
 # --------------------------------------------------------------------------
 
-def test_the_live_register_parses_and_assigns_tiers():
-    register = et.read_register(et.REPO_ROOT / "docs" / "requirements.md")
+def _live_config() -> et.Config:
+    config_path = et.find_config(HERE)
+    assert config_path is not None, "no traceability.toml found above this file"
+    return et.config_from_dict(
+        __import__("tomllib").loads(config_path.read_text(encoding="utf-8")),
+        config_path.parent, str(config_path))
+
+
+def test_this_repos_config_is_valid_and_its_register_parses():
+    config = _live_config()
+    config.validate()
+    register = et.read_register(config)
     assert register.total > 0
-    for req_type in et.LOCAL_TYPES:
+    for req_type in config.requirement_types:
         assert register.count(req_type) > 0, req_type
-    assert sum(register.count(t) for t in et.LOCAL_TYPES) == register.total
-    # The GPU-less CI host must be visible in the parse, not just in prose.
-    assert "AR-027" in register.unexecutable_ids()
-    assert register.requirements["AR-027"].tiers == {"T4"}
-    assert register.requirements["AR-012"].tiers == {"T2"}
-    assert register.unexecutable_ids() < register.ids
+    assert sum(register.count(t) for t in config.requirement_types) == register.total
 
 
-def test_the_live_register_yields_a_gate_run_that_cannot_exceed_one_hundred():
-    register = et.read_register(et.REPO_ROOT / "docs" / "requirements.md")
-    files = et.iter_source_files(et.REPO_ROOT)
-    scan = et.scan_files(files, et.REPO_ROOT)
+def test_this_repos_gate_run_cannot_exceed_one_hundred_percent():
+    config = _live_config()
+    register = et.read_register(config)
+    scan = et.scan_files(et.iter_source_files(config), config)
+    assert scan.files, "configured source roots matched no files"
     cov = et.compute_coverage(
         [i for t in scan.traces for i in t.requirements], register)
     assert 0.0 <= cov.percent <= 100.0

scripts/traceability/traceability-gate.sh

@@ -1,64 +1,62 @@
 #!/bin/sh
 #
-# Requirement traceability gate. Run locally exactly as CI runs it:
+# Requirement traceability gate. Run locally exactly as CI runs it, from the
+# component repo root:
 #
 #     scripts/traceability/traceability-gate.sh
 #
-# Writes traces-report.json and docs/traceability.md, prints the coverage
-# report, and exits non-zero when the gate fails.
+# Writes the JSON report and the markdown matrix, prints the coverage report,
+# and exits non-zero when the gate fails.
 #
-# Environment:
-#   MIN_COVERAGE    minimum overall coverage percent (default 0 - see below)
-#   ALLOW_ORPHANS   set to 1 to report orphan tags without failing
-#   TRACES_JSON     JSON report path (default traces-report.json)
-#   TRACES_MD       markdown matrix path (default docs/traceability.md)
-#   SYSTEM_SPEC     optional path to the umbrella SPEC.md, which defines the
-#                   PR/SR IDs; when given, PR/SR orphans are reported too. That
-#                   file lives in the parent project, not in this repo, so CI
-#                   normally leaves it unset.
+# This script is shared by every JRay component, so it knows nothing about any
+# one repo. All repo-specific settings - requirement ID prefixes, source
+# suffixes, scan roots, register path, thresholds - live in `traceability.toml`
+# at the component repo root. Run
 #
-# Threshold policy lives here and nowhere else. It is deliberately NOT
-# duplicated into the workflow YAML: a threshold written in two places is a
-# threshold that will disagree with itself.
+#     scripts/traceability/extract_traces.py --print-example-config
 #
-# MIN_COVERAGE defaults to 0 because almost nothing is tagged yet - tags are
-# added as the pipeline is built, so a low number today is accurate rather than
-# alarming. A zero threshold does NOT mean the gate cannot fail: orphan tags,
-# a >100% ratio, a register that parses to nothing, and an empty source scan
-# are all hard failures from day one. Raise MIN_COVERAGE as tags land; treat
-# every raise as a ratchet, never a reset.
+# for the annotated schema. A repo whose config is wrong parses zero
+# requirements or scans zero files, and the gate refuses to report rather than
+# printing a misleading 0%.
+#
+# Environment (all optional; each overrides the config file):
+#   TRACES_CONFIG   path to traceability.toml
+#   TRACES_ROOT     repo root (default: nearest dir containing traceability.toml)
+#   MIN_COVERAGE    minimum overall coverage percent
+#   ALLOW_ORPHANS   1 to report orphan tags without failing
+#   TRACES_JSON     JSON report path
+#   TRACES_MD       markdown matrix path
+#   SYSTEM_SPEC     SPEC.md defining PR/SR; enables PR/SR orphan checking
+#   PYTHON          interpreter (default: python3)
+#
+# Threshold policy belongs in traceability.toml, not here and not in the
+# workflow YAML: a threshold written in two places is a threshold that will
+# disagree with itself.
 #
 # POSIX sh, no bashisms, no jq - the extractor does its own arithmetic and
-# printing so CI needs nothing beyond python3.
+# printing, so CI needs nothing beyond python3.
 
 set -eu
 
 SCRIPT_DIR=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
-REPO_ROOT=$(CDPATH= cd -- "$SCRIPT_DIR/../.." && pwd)
-
-MIN_COVERAGE="${MIN_COVERAGE:-0}"
-TRACES_JSON="${TRACES_JSON:-$REPO_ROOT/traces-report.json}"
-TRACES_MD="${TRACES_MD:-$REPO_ROOT/docs/traceability.md}"
 
 PYTHON="${PYTHON:-python3}"
 command -v "$PYTHON" >/dev/null 2>&1 || {
-    echo "FAILED: $PYTHON not found. The traceability gate needs Python 3.9+" >&2
+    echo "FAILED: $PYTHON not found. The traceability gate needs Python 3.9+," >&2
+    echo "        or 3.11+ to read traceability.toml." >&2
     exit 2
 }
 
-set -- \
-    --root "$REPO_ROOT" \
-    --format coverage \
-    --json-out "$TRACES_JSON" \
-    --markdown-out "$TRACES_MD" \
-    --min-coverage "$MIN_COVERAGE"
+set -- --format coverage
 
-if [ "${ALLOW_ORPHANS:-0}" = "1" ]; then
-    set -- "$@" --allow-orphans
-fi
-
-if [ -n "${SYSTEM_SPEC:-}" ]; then
-    set -- "$@" --system-spec "$SYSTEM_SPEC"
-fi
+# Explicit `if` rather than `[ ... ] && ...`, because a trailing false test in
+# an && list exits under `set -e` in some POSIX shells.
+if [ -n "${TRACES_CONFIG:-}" ]; then set -- "$@" --config "$TRACES_CONFIG"; fi
+if [ -n "${TRACES_ROOT:-}" ];   then set -- "$@" --root "$TRACES_ROOT"; fi
+if [ -n "${MIN_COVERAGE:-}" ];  then set -- "$@" --min-coverage "$MIN_COVERAGE"; fi
+if [ -n "${TRACES_JSON:-}" ];   then set -- "$@" --json-out "$TRACES_JSON"; fi
+if [ -n "${TRACES_MD:-}" ];     then set -- "$@" --markdown-out "$TRACES_MD"; fi
+if [ -n "${SYSTEM_SPEC:-}" ];   then set -- "$@" --system-spec "$SYSTEM_SPEC"; fi
+if [ "${ALLOW_ORPHANS:-0}" = "1" ]; then set -- "$@" --allow-orphans; fi
 
 exec "$PYTHON" "$SCRIPT_DIR/extract_traces.py" "$@"

traceability.toml

@@ -0,0 +1,34 @@
+# Traceability configuration for scene-actor-extraction.
+#
+# Read by the shared extractor (scripts/traceability/extract_traces.py), which
+# is the same implementation every JRay component uses. Everything repo-specific
+# lives here rather than in the tool; run `extract_traces.py
+# --print-example-config` for the annotated schema.
+#
+# This file's directory is taken as the repo root, so the gate works from any
+# subdirectory.
+
+# The prefixes this repo's register defines. Nothing else enters the fraction:
+# UT/IT are evidence for requirements, PR/SR belong to the system spec.
+requirement_types = ["AR", "DP", "IR", "GR", "VR"]
+
+# C++ pipeline plus the Python tooling, optimizer and validation scripts.
+languages = ["cpp", "python"]
+
+source_roots = ["src", "tests", "scripts", "experiments", "eval"]
+
+# CI is an Intel N100 with no discrete GPU. T4 is deliberately absent: a
+# requirement verifiable only on GPU hardware is reported as tagged but
+# unexecuted and never counted as covered, because counting a test that cannot
+# run is the same failure mode as JellyTau's 158% coverage bug.
+ci_executable_tiers = ["T1", "T2", "T3", "static"]
+
+# Threshold policy. 0 today because almost nothing is tagged yet - tags land as
+# the pipeline is built. This is not a gate that cannot fail: orphan tags, a
+# >100% ratio, a register that parses to nothing and an empty source scan are
+# all hard failures already. Ratchet this up as tags land; never reset it down.
+min_coverage = 0.0
+
+# The system spec owning PR/SR is vendored per-component as a submodule. Point
+# at it once that lands to turn on PR/SR orphan checking:
+# system_spec = "scripts/vendor/jray-project/SPEC.md"