Summary

Restore browser session-tab-registry to close tracked tabs on session cleanup. Fixes a memory leak. Part of umbrella audit #2406 (B10 silent-revert pattern).

Upstream Commit

• 06a229f98f — fix(browser): close tracked tabs on session cleanup (#36666)
• Sync batch: v2026.3.7
• Classification: Production — memory leak

Files to Restore

• src/browser/session-tab-registry.ts (A — production, absent in fork)
• src/browser/session-tab-registry.test.ts (A — paired test, absent in fork)

Context

Missed during B10 sync (PR #2400) via the asymmetric revert-vs-extract split anti-pattern. Both files exist at upstream/v2026.3.22; the INCLUDE Reconciliation Gate in fork-sync SKILL § Phase D.3 now prevents recurrence.

Acceptance Criteria

• Both files present in fork main matching upstream/v2026.3.22 state
• pnpm check passes
• pnpm test passes (new test file participates and passes)
• PR cherry-picks 06a229f98f with -x to preserve upstream attribution

Execution

git cherry-pick -x 06a229f98f
# Expect minor adaptations: rebrand transforms, import-path divergence
# Pattern reference: #2402

Related

• Umbrella: Audit: upstream fixes silently lost in sync (v2026.2.25 → v2026.3.22, 32 gaps) #2406
• Prior pattern: fix(ci): replace tlon git api dependency (closes #2362) #2402
• Prevention: INCLUDE Reconciliation Gate (fork-sync SKILL § Phase D.3)