feat(typescript): add server-side memory event filters

[Jonesxq]

Summary

Add optional server-side filters to TypeScript MemoryEventClient WebSocket subscriptions. patterns, scope, and scopeId are encoded as the server's patterns, scope, and scope_id query parameters, and the same filters are retained across reconnects.

This reduces WebSocket traffic and client-side processing for high-volume event streams while preserving the existing unfiltered behavior for callers that omit options. Existing Agent.watchMemory() registrations continue to use their current client-side dispatch filtering; automatically aggregating multiple dynamic watchers with different scopes is outside this focused change because one shared WebSocket cannot represent those filters exactly.

Type of change

• Bug fix
• New feature
• Refactor / cleanup
• Docs only
• Tests only
• CI / tooling
• Breaking change

Test plan

• cd sdk/typescript && npm test -- tests/memory_event_client.test.ts (5 tests passed)
• cd sdk/typescript && npm run lint
• cd sdk/typescript && npm run build
• cd sdk/typescript && npm test (807 of 808 tests passed on Node 24.18.0; the existing memory-growth threshold test measured 31.29 MB against a 25 MB limit, while that file passed 6 of 6 when run in isolation with explicit garbage collection)

Test coverage

This repo enforces a coverage gate on every PR (see
.github/workflows/coverage.yml and
docs/COVERAGE.md).

• I ran tests for the surface(s) I changed locally.
• New code paths are covered by tests in this PR (no bare additions).
• If I removed code, I updated coverage-baseline.json in this PR only if the removal caused a legitimate regression and I called it out in the summary above. (No code was removed.)
• The coverage gate check is green in CI before requesting review.

Checklist

• I have read CONTRIBUTING.md and docs/DEVELOPMENT.md.
• Commits are signed and follow conventional-commits style. (The commit follows conventional-commits style; no GitHub signing key is configured for this account.)
• I have linked the related issue.

Related issues / PRs

Closes #90

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[github-actions]

Performance

SDK	Memory	Δ	Latency	Δ	Tests	Status
TS	500 B	+43%	1.51 µs	-25%	✓	✗

⚠ Regression detected:

• TypeScript memory: 350 B → 500 B (+43%)

[github-actions]

📊 Coverage gate

Thresholds from .coverage-gate.toml: per-surface ≥ 84%, aggregate ≥ 85%, max per-surface regression ≤ 1.0 pp, max aggregate regression ≤ 0.50 pp.

Surface	Current	Baseline	Δ
control-plane	86.80%	87.40%	↓ -0.60 pp	🟡
sdk-go	92.50%	92.00%	↑ +0.50 pp	🟢
sdk-python	93.82%	93.73%	↑ +0.09 pp	🟢
sdk-typescript	91.08%	90.42%	↑ +0.66 pp	🟢
web-ui	84.76%	84.79%	↓ -0.03 pp	🟡
aggregate	85.51%	85.75%	↓ -0.24 pp	🟡

✅ Gate passed

No surface regressed past the allowed threshold and the aggregate stayed above the floor.

[github-actions]

📐 Patch coverage gate

Threshold: 80% on lines this PR touches vs origin/main (from .coverage-gate.toml:thresholds.min_patch).

Surface	Touched lines	Patch coverage	Status
control-plane	0	—	➖ no changes
sdk-go	0	—	➖ no changes
sdk-python	0	—	➖ no changes
sdk-typescript	13	100.00%	✅
web-ui	0	—	➖ no changes

✅ Patch gate passed

Every surface whose lines were touched by this PR has patch coverage at or above the threshold.