fix(tasks): preserve dirty diff edits

[janburzinski]

Description

• fix saving edits made in diff tabs
• show dirty state on diff tabs
• keep dirty diff previews open

Screenshot/Recording (if applicable)

https://streamable.com/g0c66y

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 extends the Monaco model lifecycle to cover disk working-tree diff tabs in addition to file tabs, so dirty edits made in a diff editor survive tab-switching and renderer unmounts. It also adds a dirty indicator dot to diff tab items, prevents a dirty preview diff tab from being silently replaced, and fixes Ctrl+S to operate on the active editable path (file or editable diff).

• getEditableBufferPath + allOpenEditablePaths: new helper + computed deduplicates editable paths across panes, feeding the existing register/unregister reaction and replacing allOpenFilePaths in the lifecycle store.
• openDiffPreview dirty guard: a dirty disk-diff preview is now promoted to a permanent tab rather than replaced when a new preview is requested.
• saveAllFiles + _hasOpenEditableTabForPath: save-all now includes editable diff paths, and the clearBuffer call is guarded against clearing content that another editable tab still owns.

Confidence Score: 4/5

Safe to merge for the core happy-path flows; one edge case involving tab group transitions on dirty diff tabs can silently discard unsaved edits, already flagged in a prior review pass.

The implementation correctly extends the Monaco model lifecycle to editable diff tabs and the new tests cover the main scenarios well. The one outstanding concern — a dirty disk-diff tab that transitions to the staged group via transitionDiffTab loses its buffer content without a save dialog, because the group change causes the path to leave allOpenEditablePaths and _unregisterModels is called before the user is prompted — was introduced by hooking disk-diff tabs into the lifecycle reaction and was flagged in a prior review comment. Everything else (preview promotion, dirty indicator, save-all extension, clearBuffer guard) is well-handled.

file-model-lifecycle-store.ts and tab-manager-store.ts — specifically the interaction between the allOpenEditablePaths reaction and transitionDiffTab mutations.

Important Files Changed

Filename	Overview
apps/emdash-desktop/src/renderer/features/tasks/editor/editor-provider.tsx	Replaces activeFilePath with activeEditablePath for Ctrl+S and paste handlers — minimal, correct change that extends keyboard save to editable diff tabs.
apps/emdash-desktop/src/renderer/features/tasks/editor/stores/file-model-lifecycle-store.ts	Extends register/unregister lifecycle reaction from allOpenFilePaths to allOpenEditablePaths; fixes clearBuffer guard to use editable-path check; the transitionDiffTab scenario (disk→staged on a dirty tab) still triggers _unregisterModels and clears the buffer without a save dialog.
apps/emdash-desktop/src/renderer/features/tasks/tabs/tab-group-manager-store.ts	Adds allOpenEditablePaths computed (deduplicated across panes) alongside the existing allOpenFilePaths; clean, mirrors the existing pattern exactly.
apps/emdash-desktop/src/renderer/features/tasks/tabs/tab-manager-store.ts	Adds getEditableBufferPath helper, activeEditablePath / openEditablePaths computeds, isDirty + bufferUri on ResolvedDiffTab, and dirty-aware preview replacement in openDiffPreview; logic is correct for the happy path, though the transitionDiffTab edge case can bypass the save dialog.
apps/emdash-desktop/src/renderer/features/tasks/tabs/tab-manager-store.test.ts	New diff-tab test suite covers: editable path exposure for disk diffs, dirty-preview promotion instead of replacement, and confirmed absence of bufferUri for staged diffs; mock setup is correct and properly reset in beforeEach.
apps/emdash-desktop/src/renderer/features/tasks/view/tab-bar/diff-tab-item.tsx	Adds unsaved-changes dot indicator to diff tabs, mirroring the existing file-tab dirty indicator pattern; status icon is correctly hidden when the dirty dot is shown.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant UI as User / Tab Bar
    participant TM as TabManagerStore
    participant FML as FileModelLifecycleStore
    participant MR as ModelRegistry
    participant RPC as IPC / clearBuffer

    UI->>TM: openDiffPreview(diskDiff)
    TM->>MR: isDirty(previewBufferUri)?
    alt preview is dirty
        TM->>TM: "promote preview.isPreview = false"
        TM->>TM: create new preview tab
    else preview is clean / non-editable
        TM->>TM: replace preview in-place
    end

    Note over TM,FML: allOpenEditablePaths reaction
    TM-->>FML: allOpenEditablePaths changed (path added)
    FML->>MR: registerModel(path, disk/git/buffer)

    UI->>TM: closeTabWithGuard(tabId)
    TM->>FML: closeHandler(tabId)
    FML->>MR: isDirty(bufferUri)?
    alt dirty
        FML->>UI: confirmClose dialog
        UI-->>FML: save / discard / cancel
    end
    FML->>TM: closeTab(tabId)

    Note over TM,FML: allOpenEditablePaths reaction
    TM-->>FML: allOpenEditablePaths changed (path removed)
    FML->>FML: _hasOpenEditableTabForPath?
    alt no other editable tab for path
        FML->>RPC: clearBuffer(path)
    end
    FML->>MR: unregisterModel(uri)

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sequenceDiagram
    participant UI as User / Tab Bar
    participant TM as TabManagerStore
    participant FML as FileModelLifecycleStore
    participant MR as ModelRegistry
    participant RPC as IPC / clearBuffer

    UI->>TM: openDiffPreview(diskDiff)
    TM->>MR: isDirty(previewBufferUri)?
    alt preview is dirty
        TM->>TM: "promote preview.isPreview = false"
        TM->>TM: create new preview tab
    else preview is clean / non-editable
        TM->>TM: replace preview in-place
    end

    Note over TM,FML: allOpenEditablePaths reaction
    TM-->>FML: allOpenEditablePaths changed (path added)
    FML->>MR: registerModel(path, disk/git/buffer)

    UI->>TM: closeTabWithGuard(tabId)
    TM->>FML: closeHandler(tabId)
    FML->>MR: isDirty(bufferUri)?
    alt dirty
        FML->>UI: confirmClose dialog
        UI-->>FML: save / discard / cancel
    end
    FML->>TM: closeTab(tabId)

    Note over TM,FML: allOpenEditablePaths reaction
    TM-->>FML: allOpenEditablePaths changed (path removed)
    FML->>FML: _hasOpenEditableTabForPath?
    alt no other editable tab for path
        FML->>RPC: clearBuffer(path)
    end
    FML->>MR: unregisterModel(uri)

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_{Reviews (3): Last reviewed commit: "fix(diff): clear buffers after discard" | Re-trigger Greptile}

[janburzinski]

@greptileai

[janburzinski]

@greptileai