fix(ssh): preserve git state on disconnect

[janburzinski]

Description

this fixes two crashes i have had yesterday.

• preserve last known git state when ssh refreshes fail temporarily
• treat ssh disconnect/timeouts as recoverable git refresh errors
• prevent failed background refreshes from emitting stale/empty updates
• catch and log pty onExit handler errors instead of crashing

Checklist

• I kept this PR small and focused
• I ran a self-review before opening this PR
• I ran the relevant local checks or explained why not
• I updated docs when behavior or setup changed
• I added or updated tests when behavior changed, or explained why not
• I only added comments where the logic is not obvious
• I used Conventional Commits for commit
  messages and, when possible, the PR title

[greptile-apps]

Greptile Summary

This PR fixes two crash scenarios on SSH disconnect by teaching the LiveModel-backed SSH git layer to distinguish recoverable transport errors (disconnects, timeouts) from real git failures. A new shared transport-errors.ts module is introduced so both git-service.ts and ssh-git.ts use the same predicate; a separate fix catches errors thrown inside PTY onExit handlers before they can propagate.

• ssh-git.ts: computeRefs, computeRemotes, computeStatus, and computeHead now return Result<T, E> directly. On a recoverable SSH error they return err(error) instead of throwing, so LiveModel.scheduleBackground() routes the failure to onError (a log.warn) and keeps the last-good cached value rather than re-throwing into an unhandled microtask rejection.
• git-service.ts: Recoverable SSH errors are re-thrown through previously silent .catch(() => ({ stdout: '' })) and empty-fallback catch blocks, so they reach computeStatus/computeHead rather than being swallowed as empty results.
• local-pty.ts: onExit handler invocations are now wrapped in a try/catch that logs the error instead of propagating it through the node-pty callback chain.

Confidence Score: 5/5

Safe to merge — all changes are narrowly scoped to SSH error paths and the PTY exit callback, with no changes to happy-path logic.

The fix correctly exploits the LiveModel contract: returning err() from compute() keeps the cached value and routes the failure to onError instead of crashing. The git-service changes only affect previously-silent catch blocks that were already swallowing errors. The PTY change adds defensive error handling with no impact on normal exit flow. New tests cover the two background-refresh scenarios and the onExit handler case.

No files require special attention.

Important Files Changed

Filename	Overview
apps/emdash-desktop/src/main/core/ssh/transport-errors.ts	New shared utility that centralises recoverable SSH error detection via error codes and message regex; used by both git-service.ts and ssh-git.ts.
apps/emdash-desktop/src/main/core/runtime/legacy/ssh-git.ts	compute() functions changed to return Result<T,E> directly; recoverable SSH errors now return err() so LiveModel keeps last-good state instead of crashing via unhandled microtask rejection.
apps/emdash-desktop/src/main/core/git/legacy/git-service.ts	Recoverable SSH errors are re-thrown through previously-silent catch handlers (diff numstat, getHeadInfo, getRemotes) so they propagate up to the LiveModel boundary correctly.
apps/emdash-desktop/src/main/core/pty/local-pty.ts	onExit handler invocations are now wrapped in try/catch; errors are logged rather than allowed to propagate through the node-pty callback chain.
apps/emdash-desktop/src/main/core/runtime/legacy/ssh-git.test.ts	New test file; covers recoverable SSH error propagation through GitService, background refs refresh (LegacySshGitRepository), and background status refresh (LegacySshGitWorktree).
apps/emdash-desktop/src/main/core/pty/local-pty.test.ts	New test case verifies that onExit handler errors are caught and logged rather than thrown.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant Timer as Interval Timer
    participant Worktree as LegacySshGitWorktree
    participant LM as LiveModel
    participant CS as computeStatus()
    participant GS as GitService
    participant TE as isRecoverableSshTransportError

    Timer->>Worktree: pollStatus() invalidate()
    Worktree->>LM: scheduleBackground()
    LM->>CS: compute()
    CS->>GS: getFullStatus()
    GS-->>CS: throws SSH error
    CS->>TE: isRecoverableSshTransportError(error)
    TE-->>CS: true
    CS-->>LM: return err(error)
    Note over LM: completed=false, dirty=true
    LM->>LM: onError log.warn (no crash)
    Note over LM: cached value preserved, no subscriber update emitted

Loading

%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
sequenceDiagram
    participant Timer as Interval Timer
    participant Worktree as LegacySshGitWorktree
    participant LM as LiveModel
    participant CS as computeStatus()
    participant GS as GitService
    participant TE as isRecoverableSshTransportError

    Timer->>Worktree: pollStatus() invalidate()
    Worktree->>LM: scheduleBackground()
    LM->>CS: compute()
    CS->>GS: getFullStatus()
    GS-->>CS: throws SSH error
    CS->>TE: isRecoverableSshTransportError(error)
    TE-->>CS: true
    CS-->>LM: return err(error)
    Note over LM: completed=false, dirty=true
    LM->>LM: onError log.warn (no crash)
    Note over LM: cached value preserved, no subscriber update emitted

Loading

_{Reviews (2): Last reviewed commit: "refactor(ssh): share transport error rec..." | Re-trigger Greptile}

[janburzinski]

@greptileai