The untyped-content gate cannot fire: the phrase it greps is logged without an exception, and the trace sink it scans only takes records that carry one #3625

Found while checking whether a deliberately-degraded fixture in #3619 would red the shard. It would not — and the reason is that the gate cannot fire at all in core's test lane.

The gate

dotnet-test.yml:1504 runs check-untyped-content.sh collected-logs, which greps the collected shard logs for

stayed an untyped JsonElement

and reds the shard on a hit. It was made load-bearing on 2026-09-02 (#3056 removed the accidental type-registration that MessageService.Post's Debug serialize was performing, and the degradations it had been masking started surfacing as this warning). The script is careful in every way that matters given its input: it separates "found nothing" from "the scan failed" on grep's exit code, refuses a missing directory, and explains the fix.

The phrase cannot reach collected-logs

Both producers log it as a Warning with NO exception:

• src/MeshWeaver.Hosting/MeshNodeStreamCache.cs:2283 — logger.LogWarning("MeshNodeStreamCache.GetStream: Content for {Path} stayed an untyped JsonElement after …", node.Path, TruncateRaw(je))
• src/MeshWeaver.Hosting/MeshNodeStreamCache.cs:2717 — the same, from GetQuery

The sink that feeds the collected file takes a record only when there IS an exception:

• test/MeshWeaver.Fixture/LoggingBuilderExtensions.cs:193 — var isFaultCandidate = exception is not null && logLevel >= LogLevel.Warning;
• test/MeshWeaver.Fixture/XUnitFileOutputHelper.cs:507 — the same condition guards TestTraceLog.AppendFault

so neither warning ever reaches collected-logs/_meshweaver-test-trace.log.

The other route into the directory is off in this lane. The collect step globs */bin/*/test-logs/*.log; those per-method files are opt-in via MESHWEAVER_TEST_FILE_LOGS, which is set only in node-repo-module-pack.yml (lines 2163, 2553) — never in dotnet-test.yml.

Nothing else in collected-logs can carry it: symbols-*/ (signal deaths only), _meshweaver-memory-delta.log (numbers), _meshweaver-msg-trace.log (off unless MESHWEAVER_MSG_TRACE=1), *.dmp, and teardown-stragglers.log — which records only ObjectDisposedException-shaped stragglers and unhandled exceptions, never an arbitrary log line.

Measured locally, with a positive control

Ran a test that deliberately seeds unreadable node content (#3619's UnreadablePolicyRecordIsNotClobberedTest). The phrase was emitted — it is in the .trx StdOut, twice per arm:

[Warning] [MeshWeaver.Hosting.MeshNodeStreamCache] MeshNodeStreamCache.GetStream: Content for
Admin/UpdatePolicy stayed an untyped JsonElement after deserialization …

and in the very file CI copies to collected-logs/_meshweaver-test-trace.log:

$ grep -c 'stayed an untyped JsonElement' "$TMPDIR/meshweaver-test-trace.log"   →   0
$ grep -c 'UnreadablePolicyRecordIsNotClobbered' "$TMPDIR/meshweaver-test-trace.log"   →   817

817 records naming that test class, zero occurrences of the phrase it emitted. The control is the second number: the file is not empty, and it is not missing this test — it is missing this kind of record.

Why the existing control test does not catch it

UntypedContentDegradationGate is cited in the script as the control arm, and it checks two things: the phrase still exists in the source that emits it, and the script still greps the identical string. Both are true. Neither asks whether the phrase can reach the directory the script scans — so the subject moved (the fault sink became exception-gated) and the roots did not. That is the shape AGENTS.md names: a guard whose subject moved and whose roots did not passes having checked nothing.

This is also the third recorded instance of the same underlying trap — a diagnostic carrying no exception is dropped by the trace sink (#890 and #3413 each lost their own explanation to it). The new part is that this time it silently disarms a gate.

Options

1. Give the two LogWarning calls an exception so they reach the fault sink. Honest — a content degradation IS a fault — and it needs no workflow change. The JsonException is not always in hand at that point (the GetStream site reaches the warning precisely when nothing threw), so it may need a purpose-made exception type carrying the path and the raw JSON.
2. Add a second, unconditional sink for this one phrase — the way TestTraceLog already takes phase records regardless of exception (AppendPhase). Narrow, and it keeps the production log-level contract untouched.
3. Turn on MESHWEAVER_TEST_FILE_LOGS for core's shards. Rejected upstream already, and for a stated reason: the artifact upload then ships thousands of files.

Whatever the fix, the control test must be extended to assert reachability, not just the string: emit the phrase in a test, then assert it appears in TestTraceLog's file. A gate whose input cannot arrive is indistinguishable from a gate that passes, which is exactly what this one has been.

What I did NOT measure

I did not download a real shard artifact and list its collected-logs/. The claim rests on the source of both log calls, the source of the sink's condition, the collect step, the MESHWEAVER_TEST_FILE_LOGS grep across .github/, and the local trace-file measurement above. One gh run download <run-id> -n testResults-shard1 plus ls collected-logs/ would settle it directly.