fix: resolve multiple memory leaks causing unbounded growth

[binarydoubling]

Issue for this PR

Closes #16697

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Fixes multiple sources of unbounded memory growth across the TUI, core subsystems, and server-side components. These leaks compound during extended usage causing RAM to climb monotonically.

TUI event listener leaks:

• app.tsx: 6 sdk.event.on() calls had no cleanup — listeners accumulated on re-render. Now collected and unsubscribed via onCleanup.
• session/index.tsx: message.part.updated listener accumulated every time a session was opened. Added onCleanup.
• prompt/index.tsx: PromptAppend listener leaked on prompt remount. Added onCleanup.
• theme.tsx: process.on("SIGUSR2") handler never removed. Now cleaned up via onCleanup.
• keybind.tsx: Leader mode timeout never cleared on provider unmount. Added onCleanup.
• sdk.tsx: Event queue not cleared on context cleanup. Now zeroed out.

Core memory leaks:

• sdk.tsx: Event queue grew unbounded — capped at 1000 with oldest-event eviction.
• sync.tsx: Message trimming only removed 1 message at a time and leaked associated parts. Now removes all excess and cleans up parts. Session switching now frees previous session's data.
• lsp/client.ts: Diagnostics map grew without bound — added 200-file cap with LRU eviction, early return on empty diagnostics, and clear on shutdown.
• session/prompt.ts: Pending callbacks not rejected on cancel — now rejected to prevent promise/closure leaks.
• project/state.ts: Warning timeout in disposal never cleared — now cleared after disposal completes.
• provider/models.ts: Module-level setInterval for model refresh never cleared — now cleared on process exit.
• share/share-next.ts: Added dispose() to clear pending sync timeouts.

Collection cleanup:

• bus/index.ts: Empty subscription arrays left as tombstones after unsubscribe — now deleted.
• util/rpc.ts: Empty listener Sets left in map after handler removal — now deleted.
• pty/index.ts: Session buffer not cleared on removal — now zeroed to free memory immediately.

How did you verify your code works?

Ran the TUI against a large monorepo, switched between sessions repeatedly, and monitored RSS over ~30 minutes. Memory stabilized instead of growing monotonically. Typechecks pass cleanly.

Screenshots / recordings

N/A — not a UI change

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

See CONTRIBUTING.md for details.

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Based on my search, I found several related PRs that address memory leaks:

Potentially Related PRs:

1. PR fix(opencode): unbounded memory growth during active usage #16346 - fix(opencode): unbounded memory growth during active usage

   • Directly addresses unbounded memory growth similar to this PR

2. PR fix(lsp): ignore stderr on LSP server spawn to prevent unbounded memory growth #16241 - fix(lsp): ignore stderr on LSP server spawn to prevent unbounded memory growth

   • Addresses memory growth in LSP specifically

3. PR fix: add LRU eviction to LSP client file and diagnostics tracking #7050 - fix: add LRU eviction to LSP client file and diagnostics tracking

   • Implements LRU eviction for LSP diagnostics (similar to the diagnostics map bounding in this PR)

4. PR feat: add startup cleanup and maintenance system #16628 - feat: add startup cleanup and maintenance system

   • Related to cleanup/maintenance similar to the cleanup work in this PR

5. PR fix: resolve multiple memory leaks causing unbounded RAM growth ( Now passing: && Fixed failing tests for windows ) #13514 - fix: resolve multiple memory leaks causing unbounded RAM growth

   • Very similar title suggesting it addresses related memory leak issues

6. PR fix: add idle-timeout Instance disposal for serve mode memory #16616 - fix: add idle-timeout Instance disposal for serve mode memory

   • Related to instance disposal and memory management

These PRs may be addressing overlapping memory leak issues. You should verify if PR #16695 duplicates work from any of these, particularly #16346, #16241, #7050, or #13514.

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍

[binarydoubling]

Update: Consolidated fixes from 23+ community PRs

I've reviewed every open memory leak PR referenced in #16697 and consolidated the best version of each fix into this branch. The latest commit (b395d19) adds 17 more files on top of the original 15, bringing the total to 30 files changed.

New fixes added (from community PRs)

Fix	Source PRs	Impact
Plugin subscriber stacking — Bus.subscribeAll() unsub before re-init	#16346, #7914	Prevents permanent wildcard listener accumulation
Subagent deallocation — Session.remove() after task completion	#14650	GB-scale savings in long sessions with many subagents
SSE stream cleanup — centralized cleanup() + done guard on 3 endpoints	#15646	Prevents leaked handlers/intervals on ungraceful disconnect
Compaction data trimming — clear output and attachments on prune	#14650, #7049	Frees 200KB+ per compacted tool call
Process exit cleanup — Instance.disposeAll() with 5s timeout in finally block	#13186, #15646	Prevents zombie LSP/MCP/PTY processes
Serve command — graceful shutdown instead of await new Promise(() => {})	#13186	Fixes unreachable cleanup code in serve mode
Bash tool ring buffer — chunks array with 10MB cap instead of output += chunk	#13186, #7914	Eliminates O(n²) string growth for long commands
LSP index teardown — clear clients/broken/spawning on dispose	#16346	Prevents stale client references after teardown
LSP open-files cap — evict oldest when >1000 tracked files	#14650	Prevents unbounded files object growth
Format subscription cleanup — store and cleanup unsub handle on re-init	#10392, #7914	Prevents listener stacking
Permission clearSession() — reject pending promises on session delete	#14650, #10392	Prevents leaked promises holding closures
Question clearSession() — reject pending promises on session delete	#10392, #13186	Same as above
Session.remove() cleanup chain — calls FileTime, Permission, Question cleanup	#10392	Per-session state freed on deletion
ShareNext subscription cleanup — store unsub handles, cleanup on dispose/re-init	#10392, #7914	Prevents 4 Bus listeners stacking per init cycle
OAuth transport close — close existing transport before replacing	#9145	Prevents abandoned HTTP transports accumulating

What's NOT in this PR (and why)

Some fixes from the community PRs were intentionally excluded:

• Bun.gc() calls (fix(opencode): unbounded memory growth during active usage #16346, fix: resolve memory leaks and zombie processes from missing cleanup handlers #13186) — forcing GC is a band-aid; the actual leaks are fixed instead
• Diagnostics/monitoring module (fix: prevent memory leaks from SSE streams, LSP, Bus, and process cleanup #15646) — good idea but out of scope for a leak fix PR
• Instance idle-timeout with ref counting (fix: add idle-timeout Instance disposal for serve mode memory #16616) — valuable but architecturally significant; should be its own PR
• LSP stderr "ignore" (fix(lsp): ignore stderr on LSP server spawn to prevent unbounded memory growth #16241) — changes 40+ spawn sites across server definitions; better as a targeted PR
• LRU cache utility + provider cache bounds (fix(opencode): memory leaks in session handling #10392, fix(disposal): Complete Instance disposal chain for plugins and caches #9149) — new abstraction layer; merits separate review
• ACP session manager TTL/eviction (fix(memory): add TTL, LRU eviction, and ring buffers to prevent memory leaks #12259, fix(acp): Fix memory leak in session event streams #9146) — requires design decision on TTL values
• Startup cleanup/maintenance system (feat: add startup cleanup and maintenance system #16628) — new feature (config schema, vacuum, retention); should be separate
• AsyncQueue close() (fix: address 6 memory leaks for long-running sessions #13594) — API change to a shared utility; needs its own review
• O(n²) string concat in processor.ts (fix: resolve memory leaks and zombie processes from missing cleanup handlers #13186, fix(opencode): memory leaks in session handling #10392) — the throttled flush approach is complex; needs careful review to avoid breaking streaming UX
• SDK SSE buffer cap / abort listener { once: true } (fix: resolve memory leak issues across multiple subsystems #14650) — changes are in packages/sdk/, not packages/opencode/; separate package, separate PR

Verification

• tsgo --noEmit passes cleanly across all 19 packages
• Pre-commit typecheck hook passed on push