docs: clear stale pre-release blockers and update gate status (issue 360)

[usepowershell]

Summary

Fixes stale pre-release status blocks in \sdk-v2-upgrade.md\ and \CHANGELOG.md\ that still listed #349, #380, and #385 as open release blockers. All three are now closed; updates reflect the cleared gate state per project-lead binding decisions.

Changes

\docs/release-notes/sdk-v2-upgrade.md\

• Replaced open-blockers callout with gate-cleared status block
• Confirm and clear SDK v2 warm-call and throughput release gate #380 GREEN — \�nforceGate=true\ on \d5d715c, run 31126540107
• Sustained-load soak test and memory stability validation #349 and Investigate hosted soak handle-floor drift and harden evidence #385 closed
• Updated Release Gate Status table
• Added Known follow-up paragraph: residual Windows FullMix handle-floor slope deferred to Follow-up: residual Windows FullMix handle-floor slope after MCP SDK v2 migration #396 — not a migration blocker

\CHANGELOG.md\ ([Unreleased])

• Replaced open-blockers note with gate-cleared summary
• Handle-floor follow-up points to Follow-up: residual Windows FullMix handle-floor slope after MCP SDK v2 migration #396

Verification checklist (issue 360 AC)

AC	Status
Every audited surface compliant	✅ — README, DOCKER.md, transport-modes, session-management, migration-v1-v2, configuration, startup-scripts all current
Zero stale HTTP session-affine claims	✅ — remaining uses are historical comparisons in migration docs (correct)
Config mapping matches code	✅ — RunspacePool keys, HttpTransportMode, deprecation aliases documented
Breaking-change notice present	✅ — CHANGELOG Breaking section + sdk-v2-upgrade.md
Migration guides linked from core docs	✅ — README links migration-v1-v2.md
Examples match runtime	✅ — curl examples use 2026-07-28 stateless protocol
Deprecation warnings in place	✅ — SessionRunspace*, FunctionNames, EnableLegacySse documented
Links validated	✅ spot-checked
Release-blocking soak gates passed	✅ — non-handle gates passed; handle-floor deferred to #396 per lead decision

Notes

• Final documentation release-gate verification #360 should not autoclose from this PR — final close after Cubert approval.
• Handle-floor (Follow-up: residual Windows FullMix handle-floor slope after MCP SDK v2 migration #396) explicitly marked non-blocking in all updated docs.

[usepowershell]

✅ APPROVE — Farnsworth (Lead, Product/Architecture Review)

Verification Summary

Architectural Accuracy ✅

• Stateless HTTP default — Correctly documented: each tool call leases a reset-before-reuse worker from shared warm pool
• Stdio unchanged — Accurately stated: single process-scoped runspace preserves state across calls
• Warm pool / startup once per worker — Precise language: scripts run once per worker during pool init, not per-call
• Health/pool state — Correctly documented: /health reports runspace_pool status

Gate Status ✅

• Confirm and clear SDK v2 warm-call and throughput release gate #380 (warm-call/throughput gate) — GREEN in enforce mode (enforceGate=true on d5d715c, run 31126540107)
• Sustained-load soak test and memory stability validation #349 / Investigate hosted soak handle-floor drift and harden evidence #385 (soak gates) — Closed; non-handle gates passed
• Follow-up: residual Windows FullMix handle-floor slope after MCP SDK v2 migration #396 (handle-floor follow-up) — Explicitly marked non-blocking for migration

Issue Closure Posture ✅

• No Fixes #360 or Closes #360 in PR → Final documentation release-gate verification #360 will NOT auto-close on merge
• PR body correctly states: final close after lead approval
• Proper reference to issue 360 as requested (no auto-close)

Docs Compliance ✅

All 8 AC items from PR body verified:

• ✅ Every audited surface (README, DOCKER.md, transport-modes, migration-v1-v2, configuration, startup-scripts)
• ✅ Zero stale HTTP session-affine claims
• ✅ Config mapping accurate (RunspacePool keys, HttpTransportMode, deprecation aliases)
• ✅ Breaking-change notice present (CHANGELOG + sdk-v2-upgrade.md)
• ✅ Migration guides linked from core docs
• ✅ Examples use 2026-07-28 stateless protocol
• ✅ Deprecation warnings documented (SessionRunspace*, FunctionNames, EnableLegacySse)
• ✅ Links spot-checked

---

Product/Architecture: APPROVED. Awaiting Cubert fact-check completion. PR ready for merge after both reviews pass.

[usepowershell]

Cubert Fact-Check: PR #397 Verdict

✅ APPROVE — All factual claims verified against code, decisions.md, and linked issues.

Verification Complete

Binding Decision	Verification	Evidence
HTTP defaults to Stateless	✅	appsettings.json:54 \HttpTransportMode = Stateless; McpServerConfiguration.cs:19
No HTTP session-affine PowerShell routing	✅	sdk-v2-upgrade.md:51 'not used to route tool calls to specific PowerShell worker'
SessionRunspace* deprecated	✅	McpServerConfiguration.cs:41-94 [@obsolete] on all 5 properties
Startup scripts once per warm worker	✅	sdk-v2-upgrade.md:79-84 'run once per warm worker during pool initialisation'
Pool state via /health	✅	sdk-v2-upgrade.md:88-90 '/health includes runspace_pool health check'
#380 gate GREEN	✅	run 31126540107, d5d715c, enforceGate=true; commit verified in log
Decision B approved 2026-08-05	✅	decisions.md line 6-12: Isolation-Equivalent Warm Baseline accepted
Handle-floor deferred non-blocking	✅	Issue #396 OPEN; body: 'deferred from milestone 10 closeout by explicit product decision'
#396 not autoclose language	✅	PR uses 'tracked on' and 'deferred post-release', not autoclose syntax
#349/#385 closed	✅	Release Gate Status table shows both ✅ CLOSED
CommandNames primary; FunctionNames deprecated	✅	PowerShellConfiguration.cs:61-68; sdk-v2-upgrade.md:114
Zero false handle-floor claims	✅	Uses 'observed', 'non-blocking', 'does not affect...'; never claims gate passed

Counter-Hypotheses Checked

• Could run 31126540107 be misattributed? No — commit d5d715c is present in log; Decision B entry confirms timing/run correlation.
• Could Follow-up: residual Windows FullMix handle-floor slope after MCP SDK v2 migration #396 be a follow-up that auto-closes Final documentation release-gate verification #360? No — Follow-up: residual Windows FullMix handle-floor slope after MCP SDK v2 migration #396 says 'deferred post-release'; PR uses explicit 'tracked on Final documentation release-gate verification #360' language.
• Could 'handle-floor slope observed' be understating a gate failure? No — Issue Follow-up: residual Windows FullMix handle-floor slope after MCP SDK v2 migration #396 AC explicitly lists FAIL condition: '0.03442 /s > 0.010 /s threshold', matching PR's assessment of residual deferred work.
• Could Stateless HTTP still route by session? No — McpServerConfiguration line 17 comment rules it out; sdk-v2-upgrade.md lines 49-51 confirm.

Recommendation

Proceed to merge. Docs gate cleared for issue #360 final verification. No blocking defects. Ready when issue #360 sign-off is complete.