feat(trace-verify-ts): a TypeScript verifier for TRACE v0.2, scored against the Python one

[chernistry]

What this changes

Adds trace-verify-ts/: a second, independent implementation of TRACE v0.2 record verification, in TypeScript, plus a differential harness that scores it against the Python implementation in this repository.

It runs on WebCrypto alone: no network, no filesystem, no platform module, no runtime dependency. That is what a browser, an edge worker or a service mesh sidecar needs to check a record where there is no Python runtime, which today is every consumer that is not a Python process. ROADMAP.md lists multi-language verification libraries; this is the TypeScript one.

Why a second implementation rather than a binding

A specification with one implementation says whatever that implementation does. The value is not the TypeScript code, it is the 1644-case differential run: two implementations reading the same words and reaching the same verdict is evidence the words are unambiguous, and the cases where they do not are the places the specification is not yet saying what it means.

What it implements

The profile cutover of section 2, with the superseded v0.1 identifier rejected under its own failure code rather than as an unknown profile. RFC 8785 canonicalization, including section 3.2.2's requirement to reject an integer outside the JCS safe range, and the I-JSON rule that a lone surrogate has no canonical form. Ed25519 over the section 3.2.2 pre-image, the record with its signature member absent. Canonical unpadded base64url for the signature and for JWK members (RFC 4648 sections 5 and 3.5). RFC 7638 thumbprints and the confirmation-key binding of section 3.2.2. Freshness and nonce. The three revocation outcomes of section 3.2.3 against a caller-supplied bundle, with a bundle defect reported as an outcome rather than thrown. The chain digest of section 3.1.3, over the complete parent record with its signature present.

Schemas are compiled ahead of time with ajv, so nothing is evaluated or fetched at run time, pattern is read as ECMA-262 as JSON Schema 2020-12 requires, and format: uri is asserted rather than annotated. A test pins the SHA-256 of every schema file the validators were built from against schema/, so the validators in a build are known to come from exactly those bytes; a build made against another schema directory fails that test.

The order of the checks is the Python implementation's, so both report the same first failure for the same record.

What the differential run found

Against agentrust-trace 0.10.0 and against this tree, with identical results:

Group	Cases	Identical
Signed record under 24 verifier configurations, 59 record mutations each	1416	1053
RFC 8785 canonicalization corpus	34	33
RFC 7638 thumbprints	14	14
Chain digests over the delegation-link corpus	134	134
This repository's conformance vectors	34	34
Published conformance vectors	12	12
Total	1644	1280

Every published vector agrees, every thumbprint agrees, every chain digest agrees. The remaining 364 are 13 classes, each appearing once per verifier configuration, all argued in trace-verify-ts/differential/known-divergences.json. The ledger matches on both the case and the pair of reported reasons, so a new disagreement inside a listed family is reported rather than absorbed; each entry also declares how many cases land on it, and an entry, a pair or a count the run does not bear out fails it, so a divergence that stops happening on either side has to leave the ledger. CI reads the published vectors from a pinned checkout and asserts their case count. Nothing was adjusted to match the other side.

What was filed from it

Four of the 13 are cases where the Python implementation accepts a record this specification's own rules exclude (ledger entries 3, 8, 9, 10); two more are rejections of a different shape (entries 11, 1); two are the JSON number model (entries 7, 13). Filed at the maintainer's request, one issue per rule:

1. Pattern and format: uri anchoring (entries 8, 9). A subject ending in U+000A, U+000D or U+2028, or an appraisal.verifier ending in U+000A, passes, because Python's re anchors $ before a final newline and matches . against characters ECMA-262 excludes. verify: schema pattern and format: uri are evaluated with Python re semantics, so a trailing U+000A, U+000D or U+2028 in subject and appraisal.verifier verifies #379.
2. format: uri against RFC 3986 (entry 10). https://[::1.2.3.04]/ is accepted although dec-octet excludes a leading zero. verify: format: uri accepts https://[::1.2.3.04]/, which RFC 3986 dec-octet excludes #380.
3. Contract escape (entry 11). A non-ASCII runtime.nonce leaves verify_record as a TypeError from hmac.compare_digest. verify: verify_record leaves as TypeError when runtime.nonce is non-ASCII and expected_nonce is set #381.
4. Bundle defect rejects the record (entry 1). A revocation bundle carrying a lone surrogate makes the reference reject the record, where section 3.2.3 asks for unverified_for_revocation. verify: a revocation bundle with a lone surrogate rejects the record instead of reporting unverified_for_revocation #382.
5. Signature malleability (entry 3). A signature re-spelled with non-zero unused base64 trailing bits decodes to the same 64 bytes and verifies; section 3.1.3 digests the parent record with its signature member present, so two records that differ only in that spelling both verify and have different chain digests. A specification question rather than a defect: Four surfaces state the rules and nothing says which wins: schema, reference model, normative spec and docs disagree #247, proposed rule 2.
6. Number spelling (entries 7, 13). Section 3.2.2 fixes the safe-integer range but not the spelling of a number: iat written 1785000000.0 is an integer after JSON.parse and a float after json.loads, and a number of magnitude 2^53 or above has an RFC 8785 form on one side and none on the other (1.0e+21 is this corpus's instance). Four surfaces state the rules and nothing says which wins: schema, reference model, normative spec and docs disagree #247, proposed rule 1.

The remaining five (entries 2, 4, 5, 6, 12) are cases where both implementations reject and the stated reason differs because this one refuses a non-canonical encoding earlier; entry 6 (a signature member present as 0, false, [] or {}) is on #247 as a reading question.

Scope

No signing: a verifier that can sign is a verifier that can be made to sign. No chain walk: the delegation block is normative in v0.2 and what a verifier does with a chain of them is not, so this ships one link and leaves the policy to its caller. No key or bundle fetching, which is what keeps the package offline. No ES256 or ES384 bundle signatures: the bundle schema admits them, a signature nobody checked grounds nothing, so they are reported as bundle_signature_unsupported.

Reviewing it

The commits are separable and land in this order: the package, its tests, the differential harness, CI, the changelog entry.

cd trace-verify-ts
npm ci
npm test
python differential/generate_cases.py --external <trace-tests>/tests/vectors   # what CI runs, pinned; without it the corpus is 1632 cases
python differential/oracle.py
node differential/run.mjs
python differential/compare.py --expect-external 12

Type of change

• Non-breaking spec change (new optional field, new platform profile, informative addition)

No normative text, schema or wire format changes. The addition is a new implementation and its tests.

Spec section

Implements sections 2, 3.1.3, 3.2.2 and 3.2.3 of spec/trace-v0.2.md. Changes none of them.

Checklist

• DCO sign-off on all commits (git commit -s)
• CHANGELOG.md updated (for any normative change)
• Breaking changes marked with <!-- CHANGED: #NNN: description --> in spec text
• Backward compatibility statement included (for breaking changes)

[imran-siddique]

Please open focused issues for the reported Python bugs, each with a small reproducer and the rule it tests. Link the number-handling and signature-encoding questions to #247, keeping any proposed rule changes separate from implementation fixes.

As agreed in #247, matching Python alone does not establish correctness. Where the specification leaves a question open, we need to settle it explicitly.

[chernistry]

Done, as asked. The five Python findings are four focused issues, each with a reproducer on the public API of 0.10.0 and the rule it tests: #379 (pattern and format: uri evaluated with Python re semantics; m27, m28, m29 and m31 share one cause and one fix), #380 (format: uri against RFC 3986 dec-octet), #381 (TypeError escape on a non-ASCII nonce), #382 (a malformed revocation bundle rejects the record instead of reporting unverified_for_revocation). The number-spelling and signature-encoding questions are on #247 as proposed rules, separate from the fixes; the signature-malleability finding is the implementation face of the second and lives there.

On the verifier itself: if a separate repository is the better home for a second implementation, say so and I will move the package and its differential harness there, and this PR shrinks to the CI hook and the changelog line. Agreed on the #247 rule: agreement with the reference is not correctness. The run's value is the thirteen classes where the two disagree, and the ledger says which side each one stands on.

[lywinged]

Reviewed at da8b9f0, which is @imran-siddique's uri.ts fix on your branch rather than one of
yours. No test workflow has run on that commit: trace-verify-ts.yml has run exactly once, at
5df7fd5 one commit back, where all three Node legs passed; the only workflow that has run on
the head is the approval gate. So everything below is my own runs, on Node 22.

npm test is 74 of 74. The differential at the pinned corpus is 1644 / 1280 / 364 / 0, which
reproduces your table row for row. All four issues reproduce on the published agentrust-trace
0.10.0 wheel, on the v0.10.0 tag and on main at ccbd5b9, each with a control, and every
control fired. @imran-siddique's ask is met: four issues, each naming the rule it tests. One
caveat on his "a reproducer on the public API of 0.10.0": only #379 is self-contained. The
others take BASE, KEY and NOW from it, and #382 also needs
examples/revocation-bundle/01-…json, which is not in the wheel.

I looked for a defect in the TypeScript and did not find one. The denominator: the RFC 3986
grammar rule by rule, the base64url decoder including both unused-bit masks, the chain digest,
the revocation path, and 1700 generated JCS cases: random doubles from raw bit patterns,
safe-range integers, exponent spellings, strings over an alphabet carrying U+0000, U+001F,
U+007F, U+2028, U+2029 and three astral planes, and objects with random key sets to drive the
member sort. 152 disagreements, all 152 of them |value| >= 2^53, which is entry 13's declared
class. Zero on any string and zero on any object.

Both chain digests in your #247 comment reproduce in full. Your own sentence there gives the
class: four unused bits is sixteen spellings, and all sixteen decode to the same 64 bytes, all
sixteen verify, and all sixteen give a distinct chain digest.

Four findings. Two are about what CI can see, and two are about text that has already shipped.

1. The published-vector group has never run, and CI cannot tell

README.md:82 carries --external. The "Reviewing it" recipe does not, so a reviewer following
it gets 1632 cases and 1268 identical rather than the 1644 and 1280 above it. And the workflow
does not reach it either, for a reason that is one path:

 92:          if [ -d .vectors/tests/vectors ]; then
 93:            python differential/generate_cases.py --external "$GITHUB_WORKSPACE/.vectors/tests/vectors"
 97:        working-directory: trace-verify-ts

Line 93 knows where the checkout is. Line 92 tests the same location relative to
working-directory, so it asks about $GITHUB_WORKSPACE/trace-verify-ts/.vectors/tests/vectors,
which never exists. The else arm always wins.

That is not a contingency. In the one run of this workflow, the differential against the Python implementation job logs the checkout succeeding into .../trace-spec/.vectors at 3af2b53, and
the very next step writes 1632 cases, then cases: 1632 / identical verdicts: 1268 / known divergences: 364 / unexpected: 0. The checkout step concluded success, so the
continue-on-error beside it has never been exercised either. The pin is fine; the -d test in
front of it is what missed. "Every published vector agrees" is true today, because I ran it; what
is absent is anything that would notice if it stopped being true.

The count was in the log, so the evidence was there. What is missing is an assertion on it.
external_vector_cases returns [] for a missing root and compare.py has no floor, so nothing
in the output distinguishes twelve agreeing published vectors from no published vectors at all:
both print unexpected: 0 and exit 0.

The pin's own comment is inert for the same reason, twice over. It says generate_cases.py
"writes the SHA-256 of every file it read into build/manifest.json", and the docstring says a
later run against a different checkout "is detected rather than absorbed". That write is at
generate_cases.py:421, inside external_vector_cases and after the return [] at 388, so in
the arm CI actually takes the manifest is never written at all. When it is written, nothing reads
it: build/ is gitignored and the artifact upload takes report.json only. Recorded, not
detected, and on the path CI takes, not even recorded. (The docstring also says "beside this
file"; BUILD = HERE / "build".)

2. The ledger ratchets in one direction only

The differential does discriminate, and I should say so before the finding: replace jcs.ts:128's
sort with compareCodePoints and it is 8 unexpected and exit 1; bump the corpus to current
trace-tests and it is 1 unexpected and exit 1. The undeclared direction, which is what the
description claims, holds.

The resolved direction does not. src/base64url.ts:41 is the RFC 4648 §3.5 check that four ledger
entries and your own proposed rule 2 on #247 rest on: entry 3 (22 cases), entry 4 (22), entry 12
(16) and 16 of entry 2's 26. Set unusedBits to 0 and rebuild:

npm test       73 pass, 1 fail
differential   1644 cases, 1356 identical, 288 known, 0 unexpected, exit 0

One unit test catches it, so CI would go red, and that is worth saying plainly. But the number
the submission leads with moves the wrong way and nothing says so: 76 more agreements, 76 fewer
divergences, exit 0, because a declared entry that stops being reached is not an error here. The
upstream parity test has this half in test_no_declared_divergence_has_quietly_been_resolved. I
went looking for the test that would prove me wrong: known-divergences.json is read by
compare.py --ledger and by nothing else in the tree. Measured from the other direction too, of
entry 1's nine pairs, removing one gives 6, 5, 2, 1 or 0 unexpected depending which, and two of
the nine can be removed with nothing becoming unexpected at all.

Which is the same shape as §1. In both, the number that would give it away is printed and nothing
asserts it: 1632 where 1644 was expected, 288 where 364 was. A human reading the log sees it; no
run fails.

3. "Five of the 13 … accepts a record", on two surfaces, and the second one is wider

Four, and the five items are not five of the thirteen. Item 5 is two cases where the reference
accepts nothing: the non-ASCII nonce raises, and the lone-surrogate bundle makes it reject.
Item 2's signature clause reads the other way on your own ledger:
m05-signature-trailing-newline is rejected / signature_malformed on the Python side in all
24 configurations, and entry 5 says "Both implementations reject" in as many words. I can read "a
trailing newline in signature passes" as a claim about the pattern, which is true and is what
entry 5 describes, but the sentence above it says "accepts a record" and that is what fixes the
reading.

The classes where Python verifies and this implementation rejects are entries 3, 8, 9 and 10.
Entries 1 and 7 go the other way, this implementation verifying where the reference refuses.

Your own filing has half of this already: #379 takes m27, m28, m29 and m31 as "one cause and one
fix", which is items 2 and 3 merged and the signature clause dropped, and the description did
not follow. So: #379 carries entries 8 and 9, #380 carries 10, entry 3 is on #247 as proposed
rule 2 where you said it lives, and #381 and #382 are entries 11 and 1, which are not acceptances
and are worth filing on their own terms.

CHANGELOG.md:16 carries the same sentence and needs more than a 5. Its clause is "a
trailing newline or a carriage return in a patterned field passes", and signature is a patterned
field: #/properties/signature is ^[A-Za-z0-9_-]+$. So the category makes the same false
acceptance claim the description made, over a wider set. Two more, while you are in there:
appraisal.verifier is format: uri and carries no pattern, so entry 9, one of the four real
acceptances, is named nowhere in the changelog's five; and entry 8 is three characters, U+000A,
U+000D and U+2028, where the changelog names two. The changelog is the copy that ships, and the
description is the one that does not.

One sentence more, in both places. "A test pins the SHA-256 of every schema file the
validators were built from against schema/, so a schema edit that is not rebuilt fails rather
than passing quietly." The test is live: build clean, edit a description in
schema/trace-claim.json, run node --test tests/hygiene.test.mjs, and test 2 fails. But every
invocation in the repository builds first, so the antecedent never arises. What it does hold is
that the validators in a given build came from those exact bytes, which is what catches
TRACE_SCHEMA_DIR pointed at a released schema set, and that is worth stating as itself.
README.md:77 carries the same trailing clause. CHANGELOG.md:16 states the pinning without the
conclusion, so that one is already right.

4. Smaller

• The line numbers in #381 and #382 are not 0.10.0's. Both issues say they reproduce on
  agentrust-trace 0.10.0, and on the published wheel both do. But in that wheel the
  compare_digest nonce line is sign.py:683 and _canonical_bytes(bundle) is
  revocation.py:159; this pull request's base has them at 712 and 167, and main at 799
  and 200. #381 cites 710-713 and 712, #382 cites 166-172: the base's numbering. The two
  blocks the issues quote are identical in all three trees, so no finding changes; the files
  around them are not. Worth a minute because it is #247 item 3 in miniature, the surface
  @imran-siddique called the one that keeps producing reports: someone who installs the version
  you named lands on 683. revocation.py:16 is 16 in all three.
• When you bump the pin, the current corpus has one unexpected divergence and it is the
  harness's. 1660 / 1295 / 364 / 1 at trace-tests cf30e9b, on
  external-invalid_canonical_plain_trace: Python schema_invalid at iat, TypeScript
  invalid_argument. generate_cases.py:409 sets now from the record's own iat whenever
  that is an int, and this vector exists to carry iat: 100000000000000000000, so
  verifyRecord rejects the caller's argument before it reads the record. Given a bounded now
  the TypeScript says schema_invalid at iat too. One line, and the corpus becomes
  1660 / 1296 / 364 / 0.
• oracle.py dies on input run.mjs reports on. run_verify parses record_json and
  revocation_bundle_json outside any try, so a case whose text this parser refuses takes the
  process down: {not json gives a JSONDecodeError, a 20000-deep nested array an uncaught
  RecursionError, both exit 1 with the output file however far it got. run.mjs returns
  parse_error and record_not_object and exits 0. run_jcs at 190 has the guard; the same
  unprotected json.loads is in run_thumbprint and in the chain-digest runner, so it is three
  except arms rather than one. Latent today, since all 1644 record_json values parse, and the
  corpus that makes it live is the external one, because those are arbitrary JSON files from
  another repository.
• "The one canonicalization divergence, on 1.0e+21" is one in this corpus.
  Number.isInteger is true for every finite double at or above 2^53 and for their negatives, so
  1e22, 1e308, 1.7976931348623157e308 and -1e308 all diverge the same way: a canonical
  form on the Python side against canonicalization_failed here. That is the 152 above.
• CHANGELOG.md conflicts with main. The failing gate check is
  require-maintainer-approval.yml, not a broken build.

5. The reading questions, and one thing the instruments cannot see

Four of the thirteen are stricter-here, and three are one question: entries 2, 4 and 12 are the
RFC 4648 canonical form of a base64url member, which is your proposed rule 2. The fourth is not a
reading question. Entry 6 has both implementations rejecting a signature member present as 0,
false, [] or {}, and the difference is the reference's failure code. It is the only one of
the thirteen with nowhere filed to go.

The denominator above has a hole worth naming, because it is the same hole this review is about.
Rewriting codePointLength as value.length leaves npm test at 74 of 74 and the differential
at 1280 / 364 / 0, and so does rewriting timingSafeEqual as a === b. Neither is a defect: the
schema carries no maxLength and every minLength is 1, so the two length functions cannot
disagree about anything it constrains. But a constant-time property is not observable in a
verdict at all, so "the differential agrees" is not evidence about timingSafeEqual in either
direction, and a reader of the 1644 should know which of its silences are which.

On where the package should live: if a separate repository is chosen, pinning it from here is the
mechanism, with the -d test fixed first.

[chernistry]

Every finding reproduced here before anything changed: the -d path, the manifest written after the return [] at 388 and read by nothing, the one-way ledger (unusedBits to 0: 1356 / 288 / exit 0), four rather than five, and 683 / 159 in the wheel. Five commits on top of a merge of main (the CHANGELOG conflict), one per finding:

Finding	Commit	What fails now that did not
1. The published-vector group never ran, and nothing asserted its count	8314ff8	The checkout is required; generate_cases.py refuses a missing or empty root; compare.py --expect-external 12, the count pinned beside the ref in the workflow; the manifest is always written, printed with the count and its digest, and uploaded with the report. Without the checkout: expected 12 published-vector cases, got 0, exit 1.
2. The ledger ratchets one way	8314ff8	Each entry declares count; an entry, a pair or a count the run does not bear out exits 1. Six pairs moved from entries 1 and 2 to the entries whose fix alone resolves the case: the two of entry 1 you named, and four of entry 2 by the same rule. 364 unchanged, split 20/14/23/23/24/96/30/69/23/23/2/16/1. unusedBits = 0 now prints 1356 / 288 / 0 and 5 unreached, exit 1.
3. "Five of the 13", signature in the anchoring clause, the schema-pin sentence, 1.0e+21	ba0226f	CHANGELOG, README and the description: four (entries 3, 8, 9, 10); subject with U+000A, U+000D, U+2028 and appraisal.verifier with U+000A named as such; the pin test described by what it holds; the canonicalization class named, 1.0e+21 as its instance. The README gains a paragraph on what the differential cannot see, timingSafeEqual and codePointLength by name.
4b. now taken from an out-of-range iat	7824447	now from iat only inside [0, 2^53−1]. At cf30e9b: 1660 / 1296 / 364 / 0. The pin stays.
4c. oracle.py dies on text run.mjs reports on	99fce5e	Every Python runner reports parse_error; a RecursionError inside rfc8785 classifies as canonicalization_failed, which is what the other side reports for the same text; run.mjs gains the same parse arm on its thumbprint and chain-digest runners. Six junk cases ({not json, a 20000-deep array through each runner, a bad bundle): six verdicts on both sides, identical, exit 0.
The merge itself	6f05962	#116 changed the accepted-profiles refusal message; the oracle maps it, or 25 m16 cases read unclassified.
4a. Line numbers in #381, #382	—	A comment on each with the wheel's lines and main's; bodies untouched.
5. Entry 6 has nowhere to go	—	On #247 as a third reading question, with a reproducer.

On the pushed tree: npm test 74 / 74, ruff clean, pinned corpus 1644 / 1280 / 364 / 0 with ledger: 13 entries, 71 pairs, 0 unreached and published vectors: 12 cases from 12 files. The test workflow needs approval to run on a fork; those are the numbers it should print.

Location: wherever the maintainers want the package, the -d test is fixed first, so a pin works from here or from a separate repository.

[imran-siddique]

Alex, keep the TypeScript reference verifier and its comparison harness in trace-spec for now. This repository already contains the Python SDK, and the roadmap includes multi-language verification libraries. Keeping them together lets us review schema changes and their effect on both implementations in one place.

Shared, language-neutral conformance cases belong in trace-tests; keep consuming its pinned corpus here. trace-registry remains the home for registry inclusion-proof verification, and Bernstein's service integration stays in integrations.

Before publishing, let's choose a package name that clearly distinguishes this Trust Record verifier from the registry's existing trace-verify package. We can revisit a separate repository if release or maintenance needs justify it.

[chernistry]

Understood on location: the verifier and its harness stay here, the pinned trace-tests corpus stays the shared input, registry proofs stay in trace-registry.

Name. The registry's trace-verify is on PyPI, so the clash is in the name rather than the index, and trace-verify-ts is the same clash one suffix later. Proposed: trust-record-verify, npm, unscoped. It names what the package verifies instead of the project, which is the distinction you asked for. Checked today: unclaimed on npm and on PyPI; trace-verify is unclaimed on npm as well, which is one more reason not to sit next to it. If that reads right, the rename is one commit, package.json, the directory, the workflow paths and the README, before any publish. If it should carry the org, @agentrust-io/trust-record-verify is the same name under a scope the org would need to hold on npm.

[imran-siddique]

Alex, use @agentrust-io/trust-record-verify. It clearly names what the package verifies and follows our telemetry SDK’s naming. Please update the package, directory, workflow paths and README. We’ll confirm npm publishing access before release.

[chernistry]

Renamed to @agentrust-io/trust-record-verify: the package, the directory, the workflow and its path filters, the README, and the changelog entry.

One string keeps the old spelling, as the named constant CORPUS_SEED_DOMAIN in differential/generate_cases.py. Every key in the 1644-case corpus derives from it, so changing it reissues the corpus: I ran it renamed first and it moved 12 cases off the entry that pins them, which is the ledger doing its job on a corpus it had not seen. The constant carries that reason above it. Say the word if you would rather have the spelling gone and the ledger re-pinned against a fresh corpus.

Merging main retired five ledger entries. The four defects this harness reported are fixed — #386 for the lone-surrogate revocation bundle, #388 for subject and appraisal.verifier under ECMA-262 pattern semantics, #387 for the IPv4-in-IPv6 literal with a leading zero, #383 for the non-ASCII nonce — so the cases that recorded them stopped diverging, and compare.py failed closed on five entries no case reached. They are out, with the counts that moved with them: the c23-bundle-lone-surrogate context used to diverge on every mutation and matched first, and now falls through to the mutation families.

Current run: 1644 cases, 1412 identical, 232 known, 0 unexpected; ledger 8 entries, 33 pairs, 0 unreached; 12 published vectors, manifest sha256:869550bf03073ba3. Unit tests 74/74 on Node 20, 22 and 24.

[imran-siddique]

Merged current main and aligned the TypeScript signature check with #390. Absent, null and empty signatures now report the same failures as Python; the resolved divergence is removed. Before the fix: 48 unexpected differences. After: 1,644 cases, 1,508 identical, 136 documented differences, zero unexpected; all 12 pinned published vectors agree. All 82 unit tests pass, including three new cases that failed before the fix. This follow-up needs independent review.

[imran-siddique]

@lywinged @rajnisht7 could one of you review the latest signature-handling fix and approve if it looks right? It brings absent, null and empty signatures into line with Python #390. All 82 unit tests passed, and the 1,644-case comparison has zero unexpected differences; all 12 pinned published vectors agree. @lywinged, this follows your earlier review. One independent review is enough, and I can finish the maintainer checks afterward.

[lywinged]

Checked the follow-up at 01ca3a5 against main at 1adbe20, its second parent. Seven files
differ from the branch head; three came in verbatim from main, src/agentrust_trace/sign.py
among them, and git diff-tree --cc --name-only 01ca3a5 shows the merge itself touched only the
README, the ledger, verify.ts and units.test.mjs.

The workflow's own recipe with trace-tests pinned at 3af2b53: 1644 cases, 1508 identical, 136
known, 0 unexpected, compare.py exit 0, 12 cases from 12 files, manifest
sha256:869550bf03073ba3, 82 of 82 tests. Every figure in your comment reproduces, the 48 before
the fix included, and so do @chernistry's at 7e94708: 1412 identical, 232 known, 0 unexpected,
8 entries and 33 pairs, and 74 of 74 tests there.

The guard is right and nothing below blocks it. One disclosure, since the merge brings all
of main with it: #400 is mine, and I have not re-reviewed it here.

The 48 were created by #390, not by this branch

Before #390, absent, null and the empty string all reported signature_missing, on both sides.
That agreement was the blind spot rather than a clean bill: two of the three were wrong on both
sides at once, null by the #247 ruling and the empty string by the schema, and a differential
cannot see a defect the two implementations share. The sign.py that arrives with this merge is
what breaks the tie, which is why the fix rides on the merge commit.

Four states, each run end to end by swapping sign.py and verify.ts and rebuilding, all four
scored against the ledger this commit ships:

Python	TypeScript guard	identical	unexpected
before #390	before this commit	1412	96
before #390	this commit	1364	144
after #390	before this commit	1460	48
after #390	this commit	1508	0

identical does not depend on which ledger is in the tree and unexpected does: row one against
the eight-entry ledger @chernistry ran is his published 232 known and 0 unexpected, and 232 known
minus 136 known is exactly the 96 printed here.

Row one's 96 are m08, m09, m11 and m12 under 24 configurations, which left the ledger
because #390 made the reference call them malformed too. Row three's 48 are m06-signature-empty
and m10-signature-null under the same 24, and those are new: the reference now answers
schema_invalid at signature and signature_malformed, where the old guard answered
signature_missing to both. Row two's 144 is the 96 plus the 48, so the two effects are
independent. So #390 moved 96 into agreement and broke 48, and this commit closes those 48:
1412 + 96 - 48 + 48 = 1508, and it owns the last term. The old guard put back gives row three from
the other side: 1460, 48 unexpected, exit 1, all 48 rows printed.

One test is the only thing that separates your guard from the obvious one

I would have written encodedSignature === undefined, mirroring the value rather than the
membership. Built and re-scored, it gives the same 1508 and the same 0 unexpected. The 1644 cases
cannot separate the two: a present undefined member has no JSON spelling, the TypeScript runner
parses every case with a bare JSON.parse and no reviver, and generate_cases.py builds every
record as JSON text and never writes the token undefined.

It fails exactly one of the 82 tests, a present undefined signature is malformed, one of the
eight this commit adds. Object.hasOwn is the version that mirrors the reference's new
if "signature" not in record, and own() at text.ts:97 returns undefined for both cases,
which is why the near-miss conflates them. isPlainObject at verify.ts:229 refuses a non-object
before hasOwn is reached at 249, so the ordering holds.

Worth having on the record, since it is easy to assume otherwise: the three tests that fail before
the fix are null, present-undefined and the empty string, not absent, null and empty. The old
guard against the new tests gives 3 failures and 79 passes, and absent was already passing on both
sides.

Three small things, none of them blocking

1. README lines 119 to 125, whose numbers this commit rewrote from 232 and 8 to 136 and 7.
   "in the adversarial matrix" is false for entry 7, since jcs-10 is in the canonicalization
   corpus, the row at line 112 that prints 34 | 33; "once per verifier configuration" is false
   for four of the seven entries; and "Six classes left the ledger" introduces a list of five. The
   wording predates the commit, which read "Five classes" over a list of four.
2. The pull request description, which is @chernistry's and which git grep cannot reach, carries
   the same clause, next to trace-verify-ts/, 1280 identical and 13 classes.
3. One line on #247 would settle the empty string. The ruling there answers "present with the
   wrong type", and an empty string is present and the right type, so it does not reach the 24
   cases that turn on it. What decides them is the schema's own ^[A-Za-z0-9_-]+$, which carries
   no minLength and does not need one.

What I did not check

Node 20 and 24, Python 3.12, and the hosted job's own logs: I ran Node 22 and Python 3.11.15
against the same pinned corpus, and nine of the ten check runs on 01ca3a5 pass. The tenth is
gate, the maintainer-approval workflow waiting on this review. Also Windows, the published
agentrust-trace wheel, @chernistry's figures from before the rename, and the rest of the pull
request beyond item 2.