Commit Graph

838 Commits

Author SHA1 Message Date
Joseph Doherty 89630ee418 fix(acl): browse transit reaches the shared root folder (narrow Browse grants were unreachable)
With Security:Acl:Enabled=true, a session holding any grant narrower than
Cluster could not browse the served address space at all — confirmed by the
live gate.

Mechanism. Both realm trees hang under ONE anchor folder minted in
CreateAddressSpace: NodeId("OtOpcUa", <raw ns>). ResolveParentFolder parents
every top-level raw folder AND every top-level UNS area under it, and the
Browse override throws BadUserAccessDenied for the WHOLE call when its source
node is denied. DataPlaneAuthorizer.BuildScope split that identifier like a
path, producing {Kind: Raw, Segments: ["OtOpcUa"]} — but trie grant paths are
["raw", <RawPath segments…>] and "OtOpcUa" is never a path segment, so
PermissionTrie.HasBrowseTransit failed at the realm-child lookup and
CollectMatches yielded only Cluster-scoped grants. Deny, at the front door.

The trie already handled a zero-segment scope as "the realm root, itself an
ancestor of everything granted in that realm" (PermissionTrie.cs:101-118) —
no production path had ever produced that scope. This wires it up.

- V3NodeIds.SharedRootFolderId names the anchor identity; CreateAddressSpace
  now mints the NodeId/BrowseName/DisplayName from it (behaviour-identical,
  makes the coupling explicit).
- BuildScope maps that identifier (realm-qualified to Raw — in the UNS
  namespace s=OtOpcUa is an ordinary Area) onto the zero-segment Raw scope.
- Evaluate adds a second-realm OR-leg for Browse on the anchor only: it fronts
  both trees, so a principal whose only Browse grant lives in the UNS tree
  still enters through this raw node. Browse only; transit confers navigation,
  never read/write/subscribe.
- No trie, evaluator or builder change. No reordering above the decision cache
  — key revocation is still re-checked before the lookup — and the cache key
  is unchanged (the combined verdict caches under the anchor's own
  identifier/realm; a generation advance clears it).

Falsifications actually run (implement-then-revert-the-line, plus one
genuine red-first):

- DataPlaneAuthorizerTests: the 7 new facts were written BEFORE the fix and 4
  went red (the 3 deny-only ones passed vacuously, as a deny-only test must).
- Deleting the UNS OR-leg reddens exactly one fact,
  The_shared_root_folder_is_browsable_on_a_uns_only_browse_grant (26/27 pass).
- Dropping the realm qualification from IsSharedRootFolder reddens exactly
  A_uns_area_named_like_the_anchor_gets_no_anchor_semantics. Its first draft
  did NOT catch this — a raw-only grant is refused either way; the
  discriminating grant had to be an unrelated UNS one, whose own transit marks
  the zero-segment UNS scope the un-qualified mapping would land on.
- Disabling the BuildScope anchor branch reddens the new end-to-end fact
  NodeManagerStage6EnforcementTests.The_shared_root_folder_is_browsable_on_a_narrow_grant_and_still_filters
  (real booted server, real Browse dispatch: BadUserAccessDenied on the whole
  call), which also pins that the reference filter still withholds the
  non-granted sibling.
- Core PermissionTrieBrowseTransitTests gains 3 characterization facts pinning
  the previously-dead realm-root branch (transit true for the granting realm's
  root, false for the other realm's, false without the Browse bit). These were
  green on arrival — the trie was always correct; nothing called it.

Tests: Core 351 -> 354 passed; OpcUaServer 482 -> 490 passed. Build clean.
2026-08-18 09:45:04 -04:00
Joseph Doherty 837d8a17eb test(scripting): timeout under starvation is not a leak; share the exhaustion-reason constant
Review follow-ups to 34829ea0.

IMPORTANT - the leak filter had its own flake vector. This test saturates the
thread pool by design, and TimedScriptEvaluator starts its 5s clock at WaitAsync
rather than when the inner Task.Run gets a thread, so a legitimately-enqueued
evaluation can blow the budget while still queued and surface "script timed out
after 5.0s". The reason != exhaustion filter classified that as a raw disposed
escape and hard-failed on it - handing the test back the load-fragility the
reshape removed. Timeouts are now their own bucket, tolerated and rate-bounded
exactly as exhaustions are; a raw disposed escape still fails on first occurrence.
Doc-comment names this second residual vector alongside the exhaustion calibration.

MINOR (scope extension authorised by review) - "evaluator disposed during
evaluation" existed as three unshared literals. Promoted to
ScriptEvalFailureReasons alongside VirtualTagEvalResult in Commons.Engines (the
assembly all three already reference) and referenced from both evaluators and the
test. The timeout prefix joins it, since the test now classifies on it too. String
values are byte-identical - no behaviour change.

Falsified: with a 12ms script budget the race produced real timeouts (3/2695).
Classified as leaks (the pre-review filter) they hard-failed the test 6/6 items;
bucketed as starvation they sit 0.11% under the 10% bound and the test is green.
2026-08-18 08:05:51 -04:00
Joseph Doherty 34829ea0d7 test(scripting): Evaluate_racing_ClearCompiledScripts no longer assumes a single clear per evaluation
The racing test encoded two timing assumptions and failed under full-solution
parallel load while passing in isolation. Both are removed; no production code
changed.

1. Assertion shape. failures.ShouldBeEmpty() assumed at most ONE apply-boundary
   clear can land inside a single evaluation, so the evaluator's one-shot retry
   always suffices. Under contention two can land and the retry legitimately
   exhausts. The test now asserts the invariant the retry actually guarantees and
   which is timing-independent: no raw disposed-script failure ESCAPES the retry.
   Every failure must be the documented exhaustion outcome ("evaluator disposed
   during evaluation") and never the pre-fix generic escape ("script threw:
   Cannot access a disposed object..."), plus a deliberately loose bound on the
   exhaustion rate so the check cannot go vacuous.

2. Workload shape. The fixed 12x400 evaluations against a fixed 45s WaitAsync
   budget is CPU-dependent (every clear forces a recompile). Four concurrent
   instances of this class reproduced a hard TimeoutException 4/4 - the likely
   real shape of the reported load failure. The loops are now duration-bounded
   (10s race window or 400 iterations, whichever first); the 45s WaitAsync stays
   purely as a hang detector.

Renamed to Evaluate_racing_ClearCompiledScripts_never_leaks_a_raw_disposed_failure
so the name matches what it now asserts; the old name is cited in the doc-comment
for traceability.
2026-08-18 07:48:44 -04:00
Joseph Doherty df53391646 test(localdb): deregister preserves data + partial-flip fails loudly (review round)
Review round on 3e62f161. Two coverage gaps and three wording/comment nits.

IMPORTANT 1 — deregistration is now proven DATA-PRESERVING. The self-heal test
inserted a deployment_pointer row and rebooted unconfigured but never looked at
the row again, so a library regression that touched base-table data during
cleanup would have gone unnoticed — on the very tables that ARE the
boot-from-cache backstop, and on the default-OFF nodes least likely to notice.
The new DisablingReplication_PrunesBookkeepingButNeverTouchesTheCachedDataItself
asserts the row's CONTENT survives (not just its count — a count passes against
a cleanup that blanks columns) while __localdb_row_version and __localdb_oplog,
the bookkeeping deregistration does own, go to zero.

IMPORTANT 2 — mid-loop partial failure is documented and pinned. Both loops flip
four tables with no try/catch, so a throw on the third leaves two flipped and
propagates out of the AddZbLocalDb singleton factory, failing host start. That
is correct — a node that came up anyway would be silently capturing on an
arbitrary subset — and both library calls are idempotent, so the retried boot
completes the flip. Written into OnReady's remarks and pinned by
AFailureMidwayThroughRegistration_FailsBootLoudly_AndTheRetriedBootConverges,
which drives OnReady through a delegating ILocalDb that throws on the Nth
RegisterReplicated, asserts the throw propagates, asserts the wrapper actually
reached that call, then re-runs OnReady unwrapped and asserts all four converge.

MINOR 3 — the Boot helper now records that OnReady's null-logger fallback lands
on Serilog's static Log.Logger, which this assembly never assigns; assertions
about logging pass an explicit logger.
MINOR 5 — log wording: "are both unset" -> "are both absent — unset or blank",
matching IsNullOrWhiteSpace.
MINOR 4 — LocalDbDeploymentArtifactCacheTests said its setup "mirrors
LocalDbSetup.OnReady"; it reproduces the two tables only and registers them
unconditionally without baselining. Softened to say so and to name the
divergence as intentional and inert there.

Falsified both new pins. Wrapper set to failOnCall: 99 (never throws) => the
partial-flip pin is the SOLE failure, so it genuinely exercises the Nth-call
throw path rather than some incidental exception. Predicate forced constant-true
=> five pins red including the new data-preservation one. Both mutations
reverted.

LocalDbSetupTests 15/15. Host.IntegrationTests 226 passed / 0 failed / 5
skipped. Runtime.Tests LocalDbDeploymentArtifactCacheTests 12/12.
2026-08-18 07:42:06 -04:00
Joseph Doherty 3e62f1617b fix(localdb): registration follows replication config — baseline on enable, deregister self-heal on disable (pair-symmetric)
LocalDbSetup.OnReady registered all four replicated tables unconditionally on
every driver node, replicating or not. That was not merely wasteful (an
unreplicated node paid two INSERTs plus a json_object of the whole row inside
every write transaction, for an oplog nothing ever drained) — it made
baselineExistingRows unusable, so enabling replication on a long-running
default-OFF node converged on SUBSEQUENT WRITES ONLY and the rows already in the
file stayed invisible to the peer, silently and forever.

Registration now follows one predicate, LocalDbSetup.ReplicationIsConfigured:
LocalDb:Replication:PeerAddress OR :ApiKey non-blank. The OR is load-bearing —
only the dialling half of a pair sets PeerAddress, so keying on it alone would
strip capture from every passive node and the pair would converge in one
direction only. SyncListenPort deliberately does not join it: the passive
endpoint is fail-closed on the key, so a port with no ApiKey syncs with nobody.

  configured   => RegisterReplicated(table, baselineExistingRows: true), per
                  table, in the unchanged load-bearing DDL->register order
  unconfigured => DeregisterReplicated(table), an idempotent boot self-heal that
                  drops the capture triggers an earlier build left behind and
                  prunes that table's oplog/row-version rows. One Information
                  line, only when it actually cleaned something.

PAIR SYMMETRY: the sync handshake compares registered-table digests fail-closed,
so flipping either key is a both-nodes-together change — set it on both and
restart both. Documented in CLAUDE.md, docs/Configuration.md and the replication
runbook (which claimed "this repo never calls DeregisterReplicated").

Verified against the pinned LocalDb 0.2.1: RegisterReplicated(string, bool) and
DeregisterReplicated(string) -> bool both exist; baselining seeds
__localdb_row_version at HLC 0 and the deregister return value distinguishes
"cleaned" from "nothing to clean". No pin bump needed.

Tests: LocalDbSetupTests gains pins for both branches (configured via
PeerAddress alone and via ApiKey alone; unconfigured => no tables, zero
triggers; late-enable => an HLC-0 baseline ledger entry; the log line fires once
and only when something was cleaned) — four went red against the old
unconditional code, and all four go red again under a constant-true predicate.
LocalDbWiringTests splits its exact-set pin into a replicating graph and a
default-OFF one. LocalDbPairHarness and AlarmSfLegacyMigratorTests built their
database from LocalDb:Path alone while configuring the replication engine from a
second config — production reads one configuration, so the two are now aligned.
Host.IntegrationTests: 224 passed, 0 failed, 5 skipped.
2026-08-18 07:25:01 -04:00
Joseph Doherty e29fab19f6 test(acl): correct the array-cell comment — captured locals do take ref (re-review nit) 2026-08-18 07:13:16 -04:00
Joseph Doherty f4b91dbbab test(acl): race harness — hit diagnostics, 10k rounds, idiom notes (review round) 2026-08-18 07:10:44 -04:00
Joseph Doherty 441b34a391 fix(acl): make InvalidateIfStale a monotonic-max CAS loop — stamp publication is never deferred 2026-08-17 07:15:30 -04:00
Joseph Doherty d54b4fab62 docs(acl): fix the two comment nits from the T1 re-review — displacement precision, straggler-test claim 2026-08-17 06:09:13 -04:00
Joseph Doherty 580b77cecf fix(sql-reaper): validate the GUID suffix and QUOTENAME the drop DDL; short reaper connect timeout; mint names from the prefix constant 2026-08-17 05:52:45 -04:00
Joseph Doherty 98d6a1908e fix(acl): a stale-generation straggler can no longer roll the cache stamp backward and thrash ClearAll 2026-08-17 05:51:24 -04:00
Joseph Doherty 68461fbfb6 test(historian): justify/tighten the shutdown watch window; single read of RemoveCallCount per poll 2026-08-17 05:39:52 -04:00
Joseph Doherty 1979cf4119 fix(acl): stamp the generation on Shard so a rollover racer cannot serve a stale-generation verdict; eviction-swap capacity hint 2026-08-17 05:37:56 -04:00
Joseph Doherty 8946644bb1 test(sql): reap >24h-old orphaned test databases at fixture startup (AdminUI + Configuration prefixes) 2026-08-17 05:37:22 -04:00
Joseph Doherty 45d670928a test(historian): replace the recorder tests' fixed sleeps with bounded watches on drain-pass and truncation observables 2026-08-17 05:35:30 -04:00
Joseph Doherty 7c5a843ace docs(code): close-out comment fixes from the follow-ups review round 2026-08-17 04:32:53 -04:00
Joseph Doherty 6b46c485ef test(historian): bounded-wait durability read; honest nondeterminism notes on the #491 controls 2026-08-17 04:07:08 -04:00
Joseph Doherty d884934593 fix(acl): shard eviction swaps the shard object so _globalCount cannot over-subtract; concurrency stress test 2026-08-17 03:55:13 -04:00
Joseph Doherty c149410ba3 test(adminui): SQL-Server-backed pins for the drift watermark aggregate and the rename scan's collation widening 2026-08-17 03:53:16 -04:00
Joseph Doherty 7870c91fe4 fix(historian): a shutdown cancellation mid-drain is a pass abort, not a per-tag failure 2026-08-17 03:52:55 -04:00
Joseph Doherty dba5f806d3 fix(runtime): explicit 30s command timeout on the Direct-apply artifact read 2026-08-17 03:49:27 -04:00
Joseph Doherty c4d8e4a200 fix(acl): revalidation memo rejects empty node identifiers, mirroring the authorizer's guard 2026-08-17 03:47:19 -04:00
Joseph Doherty 445bb855e2 fix: release the alarm drain latch on escape; cancel before disposing the page poll timers 2026-08-16 05:40:27 -04:00
Joseph Doherty dbc9223206 docs(code): correct comments stale after the perf remainder 2026-08-16 05:09:00 -04:00
Joseph Doherty 451273c860 test(historian): pin the failed-batch-append branch; correct its loss-accounting docs
The batched ingest's append-failure catch had zero coverage, and two doc
statements overstated the loss: the Warning said the burst's values were
"dropped", and RecorderStatus.OutboxAppendFailures said "the value was
dropped, not recorded". The outbox contract is prefix-never-orphan, so a
partial-prefix failure leaves entries durably queued that drain normally.

- New test pins the branch: one 3-item burst whose group commit commits a
  1-entry prefix then throws => OutboxAppendFailures == 1 (per burst, not
  per value), TotalRecorded == 0, actor alive, and the prefix still reaches
  the writer via the post-failure DrainTick (drainInterval 30s, so the
  steady cadence cannot account for it). Falsified twice: counting per item
  and dropping the drain nudge each turn it red.
- Second test pins the OperationCanceledException filter from its
  observable side - a cancel that is NOT shutdown is metered, not swallowed.
  Removing the 'when (_lifetime.IsCancellationRequested)' turns it red. The
  shutdown side has no cheap seam (the counter dies with the actor).
- Docs corrected: OutboxAppendFailures counts FAILED BATCH APPENDS, one per
  burst whatever its size (a granularity change from the per-value era), and
  is not a count of values lost; TotalRecorded under-counts when a commit
  fails after a partial prefix. Log message says "failed to append" and
  names the prefix. No functional change beyond the message string.

Also folds in the DrainBatchSize default alignment behind 0298a0b9: the
recorder's two ctor defaults and its non-positive fallback still said 64
while ContinuousHistorizationOptions.DrainBatchSize now defaults to 1024.
No test pinned the old 64.
2026-08-16 04:50:30 -04:00
Joseph Doherty 0298a0b944 chore(historian): batch-era defaults + appsettings/doc alignment 2026-08-16 04:48:55 -04:00
Joseph Doherty 5b92eb0ff6 perf(runtime): direct-mode artifact read piped off the host mailbox 2026-08-16 04:48:02 -04:00
Joseph Doherty ca87329a83 fix(adminui): dedup + chunk the rename script-scan OR-chain 2026-08-16 04:36:03 -04:00
Joseph Doherty 384568b47a perf(historian): batch ingest — one group commit per value burst 2026-08-16 04:33:35 -04:00
Joseph Doherty aad7583b79 test(acl): pin TranslateBrowsePath survivor order through the compaction 2026-08-16 04:29:27 -04:00
Joseph Doherty b6275f439c perf(runtime): per-driver index for connectivity fans; comms-loss is one batch 2026-08-16 04:27:20 -04:00
Joseph Doherty 684e59d871 perf(adminui): drift chip recomposes only when the config-edit watermark moves 2026-08-16 04:25:56 -04:00
Joseph Doherty a76b4e0740 perf(historian): bounded-parallel per-tag drain (DrainConcurrency, default 8) 2026-08-16 04:21:18 -04:00
Joseph Doherty d8a17f2e34 perf(acl): authorizer hot path — cache lookup before scope build, lazy deny reasons 2026-08-16 04:19:47 -04:00
Joseph Doherty fbe8aaad9d perf(acl): dedup subscription revalidation by (session, node) 2026-08-16 04:18:03 -04:00
Joseph Doherty 140bf0c131 perf(adminui): pooled DbContext factory; role-grants reads per-call, not per-circuit 2026-08-16 04:05:34 -04:00
Joseph Doherty 3795899d10 perf(adminui): 5s snapshot cache in front of the script tag catalog 2026-08-16 04:05:07 -04:00
Joseph Doherty ba977dbe0d perf(adminui): raw tree renders tag rows from a projection without TagConfig 2026-08-16 04:04:32 -04:00
Joseph Doherty fa36d64e8f perf(adminui): one guard round-trip per bulk reference add 2026-08-16 04:03:49 -04:00
Joseph Doherty 541a223b96 perf(acl): O(n) browse/translate filtering compaction 2026-08-16 04:03:32 -04:00
Joseph Doherty 6ff64ca067 perf(historian): group-commit batch append on the historization outbox 2026-08-15 21:40:04 -04:00
Joseph Doherty debd44c213 perf(acl): per-session decision-cache shards — a crawl no longer evicts the fleet 2026-08-15 21:38:48 -04:00
Joseph Doherty 3122728593 test(runtime): serialize meter-asserting publish-actor suites (cross-collection counter pollution) 2026-08-15 18:16:59 -04:00
Joseph Doherty d787502d54 fix(opcuaserver): degraded applies re-diff instead of losing nodes; in-place UNS mirror updates; sever inverse edges
C1 — a non-rebuild apply reporting failedNodes > 0 no longer advances _lastApplied.
Pre-delta-materialisation the full passes re-ensured every node on every apply, which
silently repaired any prior swallowed sink fault. The delta path removed that accidental
self-healing: a failed node sat inside _lastApplied, never appeared in a diff set again,
and EnsureVariable early-returns on the ones that landed — so it was lost until an
unrelated change forced a rebuild. The advance also moved to AFTER the materialise
passes, so a throwing pass leaves _lastApplied at the previous composition too. A
rebuild still advances even with failures (the ratchet is its resync path).

I2 — a UnsReferenceDelta whose identity is unchanged (same NodeId, EquipmentId and
BackingRawPath) is now applied in place via UpdateTagAttributes(Uns) instead of
remove+recreate, so the mirror's MonitoredItems survive an operator historizing or
reshaping the raw tag behind them. Remove+recreate stays for identity-changing deltas
(re-point, effective-name edit).

I3 — RemoveVariableNode severs the inverse half of every outgoing Organizes edge, the
variable-node counterpart of UnwireAlarmNotifiers. Rebuilds used to sweep these up;
surgical applies made rebuilds rare, so they accumulated on the raw node for the life of
the process.

I5 — added UNS reference variables are announced (their equipment folder is the parent,
already the Uns realm). Raw adds still are not; the gap comment now says so honestly
rather than calling it neutral and pre-existing.

I4 + M1 — corrected two comments that no longer described the code: the "re-point →
rebuild" claim in ApplyPureRemove, and the "N lock acquisitions" rationale for the delta
passes (Ensure* early-return on a dictionary probe before the lock).
2026-08-15 17:53:26 -04:00
Joseph Doherty 0dbbb5ac6b fix(runtime): stash dedup + applying-wedge watchdog; cache-failure diagnostics 2026-08-15 17:43:15 -04:00
Joseph Doherty bfbdce32e4 perf(opcuaserver): non-rebuild applies materialise the delta, not the composition 2026-08-15 17:26:53 -04:00
Joseph Doherty 14c31941c7 fix(runtime): parallel-safe decompression limit; tighten ParsedDeploymentArtifact surface 2026-08-15 17:16:09 -04:00
Joseph Doherty 5f2e60278c perf(runtime): apply-path cache write off-mailbox; stash deferred dispatches 2026-08-15 17:12:01 -04:00
Joseph Doherty 875ec9fe47 fix(opcuaserver): UNS reference nodes repair on backing-tag historian/shape edits
Adversarial review of 9f68f272 (classifier: non-alarm raw-tag deltas became
surgical) found stale UNS inheritance after a surgical raw edit. Editing a raw
tag's IsHistorized / HistorianTagname / IsArray / ArrayLength left every
referencing UNS node STALE: none of those fields were on UnsReferenceVariable,
so no coincident UnsReferenceDelta fired; the applier updated the raw node in
place; and EnsureVariable early-returns on an existing node. Consequences:
HistoryRead through the UNS NodeId served a different series than through the
raw NodeId (breaking the documented dual-registration invariant), a
de-historized tag kept serving history via UNS, and a scalar->array flip left
the UNS mirror scalar AND writable (bypassing the array read-only write gate).

UnsReferenceVariable now carries Backing{IsHistorized,HistorianTagname,IsArray,
ArrayLength}, copied from the backing tag's TagConfigIntent at compose time, so
record equality makes the reference Changed in the SAME plan. Both deltas are
non-rebuild kinds, so the existing machinery repairs the mirror surgically:
remove-previous in Apply, recreate in MaterialiseUnsReferences. That pass now
reads the four values from the RECORD (the single truth the planner diffed)
instead of a rawByPath back-lookup, preserving historian resolution exactly
(blank override => BackingRawPath, which is the backing tag's NodeId).

The artifact-decode seam needs no change: DeploymentArtifact.BuildRawAndUnsSubtrees
drives AddressSpaceComposer.Compose verbatim, which is what guarantees byte-parity.
The classifier needs no change either (a UnsReferenceDelta never forces Rebuild);
its comment now records why.

Also from the same review: a three-place-contract comment on RawTagPlan's
hand-written Equals naming its two downstream consumers, plus classifier pins for
the .Any(!eligible) quantifier, an ArrayLength-only delta, and an
alarm-content-only delta.
2026-08-15 17:11:03 -04:00
Joseph Doherty 9dbd5e96f7 perf(controlplane): gzip artifact blob inside the hashed bytes (~10-20x smaller)
ConfigComposer gzips the serialised snapshot (CompressionLevel.Fastest)
immediately after SerializeToUtf8Bytes and BEFORE taking the SHA-256, so
the compressed bytes ARE the artifact everywhere: Deployment.ArtifactBlob,
the LocalDb cache chunks, the gRPC fetch stream, and the RevisionHash a
FetchAndCache node verifies against. The invariant the deploy path rests on
— RevisionHash == SHA-256(stored/wire bytes) — is preserved, which is what
leaves the fetcher, the cache and the serve path untouched: nothing between
the composer and DeploymentArtifact.Open ever looks inside the blob.

Read side: Open() sniffs the gzip magic 1F 8B (valid JSON can never start
with 0x1F, so no framing of our own is needed) and inflates through a size
guard — MaxDecompressedBytes, 512 MiB, internal + mutable so the guard can
be exercised without inflating half a gigabyte per test run. Pre-upgrade
uncompressed blobs take the identical path they always did.

Every decompression failure — corrupt stream, truncated stream, over-limit
inflation — is reported as JsonException, the same exception family the
malformed-JSON path already owns. So the lenient static wrappers still
degrade to empty results and the apply paths still fail the apply and keep
last-known-good (#485); no caller's decision changes because the reason the
bytes are unusable changed.

gzip output is not guaranteed byte-stable across .NET releases. Harmless
here: the hash is computed FROM the emitted bytes at compose time and never
re-derived from the JSON, so the worst an implementation change costs is
one spurious "changed" revision after a runtime upgrade. Snapshot
determinism is unaffected — compression wraps the final bytes and reorders
nothing.

Tests: gzip/uncompressed parity through both the instance parses and the
statics, corrupt-gzip leniency through the wrappers, the size guard (with a
falsifiability control proving the same bytes inflate fine under the
production limit), and composer-side blob-starts-with-1F8B +
RevisionHash == SHA256(blob) with a control proving the hash is NOT over
the JSON.
2026-08-15 17:00:19 -04:00