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Fix iOS TestFlight reconnect loop from surface-lane credit exhaustion - #15485
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Pin the concurrent-open regression behind #15482: native stream opens that wait for phone credit must reserve lane capacity before suspension. This test is based on the evidence and regression in #15135. Co-authored-by: Abdulaziz Albahar <67667005+azooz2003-bit@users.noreply.github.com>
Keep surface event lane ownership with the admitted host connection: only the focused terminal gets a dedicated stream, pending native opens reserve capacity, and released generations cannot reopen stale streams. Background render output stays on the shared lane, so a phone's negotiated uni-stream credit cannot be exhausted by LRU churn. Focus transitions happen after authorized input succeeds and reset the old lane before reprioritizing the new one. The implementation follows the independently observed regression and coverage in #15135; the existing PR remains untouched. #15429's broad transport rollback is not applied because the deterministic failure is lane admission/churn, while #15475's unresolved dial lifecycle and the separate relay credential incident remain independent. Co-authored-by: Abdulaziz Albahar <67667005+azooz2003-bit@users.noreply.github.com>
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📝 WalkthroughWalkthroughSurface event lanes reserve capacity during pending opens and reject excess or stale generations. The event queue assigns dedicated lanes to focused surfaces. Interactive-surface reports trigger serialized focus transitions, lane releases, and full-frame resynchronization. ChangesFocused Surface Event Lanes
Priority: ⬆️ High Estimated code review effort: 4 (Complex) | ~45 minutes Change: Bug fix · Severity of issue fixed: High Sequence Diagram(s)sequenceDiagram
participant TerminalLaneServer as MobileHostIrxTerminalLaneServer
participant Runtime as MobileHostIrxRuntime
participant Writer as MobileHostIrxEventWriter
participant Service as MobileHostService
participant Queue as MobileHostConnectionEventQueue
TerminalLaneServer->>Runtime: report interactive surface after continuing input
Runtime->>Writer: await reportInteractiveSurface(surfaceID)
Writer->>Service: invoke registered interactive-surface handler
Service->>Queue: apply serialized focus transition
Queue-->>Service: return released surface generations
Service->>Writer: releaseSurfaceLanes(generations)
Suggested reviewers: Merge Risk: 🔵 Low · up to A focus change can leave an older render-grid frame queued when surface-key spelling varies, causing a brief stale display. Correct the eviction matching before merge if practical; the remaining risk is bounded. Security Architecture ReviewSecurity architecture risk: 🟡 Moderate · up to The new handoff design reduces stream exhaustion and keeps lane state tied to a connection. The reviewed paths did not establish a new authorization bypass or cross-connection exposure, but correct recovery depends on several asynchronous transitions that have not been validated under live reconnect conditions. Retained concerns Security review detailsSecurity Blast Radius
Trust Boundaries and Controls
Resilience and Maintainability Implications
Hardening Proposals
🚥 Pre-merge checks | ✅ 23 | ❌ 2❌ Failed checks (2 warnings)
✅ Passed checks (23 passed)
Full details: Linked Issues checkExplanation Issue [ Full details: Docstring CoverageExplanation Docstring coverage is 18.35% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 109 functions across 13 files. (1 skipped: 1 unsupported.) ✨ Finishing Touches 💡 1📝 Generate docstrings 💡
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Record the newest requested generation before a native stream open suspends, so an older pending open cannot install after a newer one. Add deterministic coverage for the overlapping-open race. Co-authored-by: Abdulaziz Albahar <67667005+azooz2003-bit@users.noreply.github.com>
Keep this issue branch at the current origin/main submodule pointer after the catch-up merge.
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The catch-up merge uses main's 9961d09b pointer; keep the issue branch aligned with that exact superproject state.
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…reconnect-loop # Conflicts: # Sources/Mobile/MobileHostIrxTerminalLaneServer.swift
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A connection actor can re-enter while a lane writer is suspended. Guard stale focus continuations by transition generation, and retain timed-out native-open capacity until the late stream is reset. Add deterministic coverage for both races. Co-authored-by: Abdulaziz Albahar <67667005+azooz2003-bit@users.noreply.github.com>
Move the interactive-surface callback into the accepted input outcome after delivery admission and PTY queueing. A mismatched or unavailable frame now receives its acknowledgement without stealing another surface's lane. Also fix the late-open regression test helper and explicit outcome assertions. Co-authored-by: Abdulaziz Albahar <67667005+azooz2003-bit@users.noreply.github.com>
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Document that the input-only baseline focus is authorized by the admitted peer and validated surface before any input frame arrives.
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Keep the reentrant focus regression independent of helpers declared in other XCTest files so the app-host test target compiles in isolation.
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Inline comments:
Review comments at @cmuxTests/MobileHostSurfaceEventLaneTests.swift:
- Around line 161-200: Update
staleFocusContinuationCannotReprioritizeAfterANewerFocus to await confirmation
that the writer received the surface-b focus note before releasing the blocked
first operation. Reuse or add a writer synchronization signal keyed to the noted
surface so the test deterministically verifies the newer focus transition has
started.
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The reentrant focus test now waits for surface-b's writer note before releasing surface-a, so it proves the stale continuation is suppressed instead of relying on task scheduling.
Keep a surface lane's capacity reservation until native priority has been applied, then revalidate enablement and generation before installing it. Track detached finish/reset operations so connection shutdown can cancel owned work without losing late-open accounting. Add deterministic coverage for priority suspension and release races.\n\nCo-authored-by: Abdulaziz Albahar <67667005+azooz2003-bit@users.noreply.github.com>
The file-length split keeps queue and connection focus extensions in separate files; use module-internal members so those extensions compile without widening the public API.
Expose the queue's shedding summary at module scope for the cross-file focus extension and use a non-public Foundation import. The previous current-head CI failure was a Swift access-control error, not a test failure.
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only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
Review comments at
@Packages/macOS/CmuxMobileHost/Sources/CmuxMobileHost/MobileHostConnectionEventQueue+Focus.swift:
- Around line 23-37: Update removeRenderGridEventsLocked to compare canonical
surface keys when selecting queued render-grid events for removal,
canonicalizing both the requested surface IDs and each event’s coalesce key so
frames queued under older raw-key spellings are removed on eviction.
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Packages/Shared/CmuxIrxTransport/Sources/CmuxIrxTransport/IrxSurfaceEventLanes.swiftPackages/Shared/CmuxIrxTransport/Tests/CmuxIrxTransportTests/IrxServerEventLaneHubTests.swiftPackages/Shared/CmuxIrxTransport/Tests/CmuxIrxTransportTests/IrxSurfaceEventLaneTests.swiftPackages/macOS/CmuxMobileHost/Sources/CmuxMobileHost/MobileHostConnectionEventQueue+Focus.swiftPackages/macOS/CmuxMobileHost/Sources/CmuxMobileHost/MobileHostConnectionEventQueue.swiftSources/Mobile/MobileHostIrxRuntime.swiftSources/Mobile/MobileHostService+SurfaceFocus.swiftSources/Mobile/MobileHostService.swiftcmux.xcodeproj/project.pbxproj
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Document why focus routing lives in its own extension file, preserving the repository Swift file-length budget without changing runtime behavior.
Surface focus lookup already canonicalizes terminal IDs, but queued render-grid entries can retain older raw spellings. Canonicalize both the eviction set and queued coalesce keys so focus handoff removes every stale frame, with focused queue coverage.
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Taking the conflict off your plate since this has been sitting since yesterday. Auto catch-up gave up on I have a session resolving it now, on your branch, with instructions to keep both sides' intent rather than pick a side, to push only a plain merge commit, and to stop and report rather than guess if main's assertions and yours turn out to actually contradict. No force-push, no behaviour changes, nothing but conflict resolution. I will post the new head SHA here when it lands. Shout if you would rather do it yourself and I will back off. Not touching anything else on the PR, and not merging it: the iOS lane is dispatch-only anyway, so that call stays yours. :) — Raindrop g2 🫧 / Run: run_worker_20260930_3fc64ba6 |
Resolve cmuxTests/MobileHostOrderedInputTests.swift by retaining the branch's fixed UUID inputs and main's canonical ordering-key assertions and helper. Preserve the branch's vendor/bonsplit submodule pointer. Catch-up-previous-head: e3fb1df Catch-up-base: af7e327 Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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Merged and pushed: head is now The conflict in
The resolution keeps main's precondition, helper and comment, and keeps your fixed literals rather than the random ones, since two distinct literals satisfy the different-buckets requirement deterministically instead of per run. Nothing else in the file changed, and the merge commit contains nothing but conflict resolutions. Verified: both submodule gitlinks are byte-identical to what your branch had before the merge ( Not verified, and CI has to be the judge: nothing Swift was compiled or run. This is a Linux host, and the iOS lane is dispatch-only anyway, so getting real signal on this needs a dispatch. That call and the merge are yours; I have not touched labels, auto-merge or anything else on the PR. :) — Raindrop g2 🫧 / Run: run_worker_20260930_3fc64ba6 |
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Summary
The 2026-09-25 transport batch let background terminal output repeatedly churn per-terminal QUIC streams. The affected TestFlight phone opened 40–60 uni-streams against a 40-stream credit; pending opens then timed out, control repair/redial repeated, and the phone admitted 24 sessions in 21 minutes.
This PR makes the admitted host connection own surface-lane focus. Only the focused terminal receives a dedicated render-grid stream; background surfaces stay on the shared events lane. Pending opens, installed lanes, and native finish/reset operations reserve one bounded stream budget. A disable/re-enable epoch quarantines late native opens, canonical surface keys keep focus, generation, poison, and route state together, and a temporary native lane limit pins the surface to the shared lane until a full frame re-bases it.
The comparison against #8531 finds the earlier relay/session flap evidence, while #15475 remains the separate unresolved-dial lifecycle and cancellation bug. This PR does not change that dial owner or claim the missing relay-credential cause. PR #15429 remains evidence only: its Iroh rollback, pin revert, and negotiation disablement are not required to reproduce or prevent the lane-credit failure here. The independent lane-churn reproduction in PR #15135 is credited without taking over that branch.
Closes #15482.
Testing
0ff89bcbb3crecords the red pending-open regression;90a2600e2d0and later commits repair lane admission, generation quarantine, focus ordering, and background-output routing.b01c662a1feadds deterministic tests for pre-disable opens, release cleanup during fallback, retiring-stream capacity, canonical key/poison state, and shared-lane fallback.c084fec2b18implements the lifecycle and canonical-identity repair, then merges withorigin/mainat58a9cbca53cin744a9c1cdea.python3 scripts/verify-local.py --all, Swift syntax, wiring, workspace package groups, determinism,swift_file_length_budget.py, andgit diff --checkpass. No local Xcode build, Swift build/test, or XCUITest was run per the issue instructions.Changelog
Fixed: focused mobile render output no longer churns native uni-streams or lets pending/retiring streams exhaust phone credit.
Demo Video
Not applicable: this is a transport and reconnect fix without a deterministic visual UI change.
Checklist
Summary by cubic
Fixes the iOS TestFlight reconnect loop where background render-grid output churned per-terminal QUIC streams and exhausted the phone's negotiated uni-stream credit. Closes #15482.
Written for commit 5faf56c. Summary will update on new commits.
Summary by CodeRabbit