chore: advance eve compatibility baseline to 0.29.4

[ncosentino]

Advances the pinned compatibility baseline from eve 0.27.6 (message-stream protocol 19) to eve 0.29.4 (protocol 20), so the C# client is gated against what eve actually ships today.

Why

CI boots a real eve server and runs the C# client against it — that fixture is the strongest evidence this repository produces. It was pinned to 0.27.6, which predates:

• the durable meta.id stream event identifier ([Upstream eve] Expose stable stream event IDs #24, merged in feat: expose stable eve stream event ids #27), and
• the framework-owned input-request kind discriminator ([Upstream eve] Preserve framework-owned input request kinds #25, merged in fix: preserve framework-owned eve input request kinds #26).

Both only exist from eve 0.28.0. Against a 0.27.6 server the probe could therefore only prove the absence-tolerance half of each contract; the presence half was covered by handwritten payloads. Bounded catch-up reads were in the same position: 0.27.6 accepted includeTailIndex=1 but never reported x-eve-stream-tail-index, so that path was unreachable against a real server.

Upstream risk review

Read the full eve changelog for 0.27.7 → 0.29.4. There are no major/breaking sections — only minor and patch. The one entry marked "Breaking" (7ff4f77, in 0.28.0) is a TypeScript type change (MessageStreamEvent becoming canonical, HandleMessageStreamEvent kept as a deprecated alias); it is additive on the wire and does not affect a .NET client.

The 0.29.0 minor changes remove CLI surface (/channels, eve channels add, eve trace → eve traces). The fixture only invokes eve build and eve start, both verified working.

Changes

• Fixture pinned to eve@0.29.4. ai moves 7.0.34 → 7.0.42 to satisfy eve's ^7.0.38 peer range. The shipped package remains dependency-free — this is test-fixture-only.
• EveProtocol.ReferenceEveVersion → 0.29.4, MessageStreamVersion → 20.
• README reference commit → 85c1dd7 (the eve@0.29.4 tag), which is what the eve-client-upstream-radar skill parses, so future parity scans compare from the new baseline.
• Probe assertions flipped from absent to required:
  • every event of a turn carries an evt_-prefixed Crockford base32 ULID, and no identifier repeats;
  • the approval-gated pause arrives as tool-approval → EveInputRequestKind.ToolApproval;
  • a real bounded catch-up read is verified against the durable tail header instead of asserting the header is missing.
• run-client-probe.mjs reads the fixture's installed eve version instead of hardcoding it, and the two workflow step names are now version-agnostic so the next bump does not touch CI.
• CHANGELOG.md records the baseline move plus the two features merged in fix: preserve framework-owned eve input request kinds #26/feat: expose stable eve stream event ids #27, which those PRs did not add.
• Documentation updated across README.md, AGENTS.md, docs/index.md, docs/compatibility.md, docs/streaming.md, docs/attachments-and-input.md, and docs/authentication.md.

Validation

Everything below was run on this branch.

Gate	Result
dotnet format --verify-no-changes	clean
dotnet build -c Release	0 warnings, 0 errors
dotnet test -c Release	100 passed, 0 failed, 0 skipped
npm ci + npm run test:client (real eve 0.29.4)	passed
mkdocs build --strict	built
python -m unittest discover -s scripts/tests	6 passed
Invoke-Pester (upstream radar)	16 passed, 0 failed
radar baseline parse	EveProtocol.cs = 0.29.4, README = 0.29.4 @ 85c1dd7… — consistent
dotnet pack + validate-packages.ps1	validated 0.1.0-alpha-0002-g455c5a97a3
test-package-consumer.ps1	clean consumer built

The flip was empirically driven, not assumed. Running the old probe unchanged against 0.29.4 failed with:

The text turn produced 'session.started' with identifier 'evt_01KYXGNEJ9H98126J96N1NDNDS',
but eve 0.27.6 emits stream protocol 19, which stamps none.

That is the real server proving meta.id projection works end to end. Tail-index support was likewise confirmed twice — statically in eve's compiled channel (EVE_STREAM_TAIL_INDEX_HEADER is set when a tail is resolved) and dynamically by the now-strict probe assertion passing.

Disclosed gaps

HIGH — none.

MEDIUM

• The CI gate no longer exercises protocol-19 tolerance against a real server. Absent identifiers and absent discriminators are still handled, and are covered by contract tests, but there is no longer a live protocol-19 server in CI. Keeping one would mean running two fixtures; that tradeoff is documented in docs/compatibility.md rather than silently dropped.
• The fixture ai bump is required by eve's peer range, so fixture and eve versions are now coupled on upgrade.

LOW

• 0.24.6 and 0.27.6 rows are retained in the compatibility table as tolerated-but-not-gated, reflecting reality rather than implying continued verification.
• The probe hardcodes the evt_ prefix and 26-character Crockford alphabet rather than importing a shared validator, matching upstream's own shape-only check.