feat: find-in-files sidebar, command bar with :cd re-root, terminal tabs + diff viewer

[jaivial]

1. Summary

SpiceEdit had no way to search across a project from the sidebar, no way to change the working directory once the editor was running, and no shell access. Users opening spiceedit in a directory had to quit and relaunch from another path to browse a different project, and grep-style cross-file search only existed as a centered modal that clobbered its state on every open.

This PR adds four user-facing features built on the existing modal and event-loop patterns. First, a persistent Find-in-files panel in the sidebar with a Files/Find header tab strip — a second grep surface whose query and results survive independently of the Esc-F modal, grouped into per-file accordions with click-to-jump. Second, a command bar (Esc-: or the menu) whose first built-in command is cd: it re-roots the file tree, the finder's project index, git status and every search surface at the target directory — nvim's :cd behavior — with bash-style Tab completion (common-prefix extension, then cycling; ~, absolute and relative paths; trailing-slash drill-down). Third, terminal tabs: a PTY-backed shell runs inside an editor tab, opened with Esc-`, the ≡ menu, or a "+" button pinned to the far right of the tab bar — keystrokes go straight to the child shell, and the tab closes with its usual × affordance. Fourth, a git-changes diff viewer, plus a fix so absolute-path completion splices the full directory prefix back into the token.

All six commits were developed and merged incrementally via fork PRs #1–#3 with go test -race ./... green at every step.

2. Root Cause (bug fix df72919)

• Symptom: typing cd /var/www/new and pressing Tab completed to bare newvillacarmen, dropping /var/www/ from the token.
• Root cause: commandSearchBase in internal/app/commandbar.go returned an empty splice prefix for absolute tokens, so candidates were inserted without their directory part.
• How the fix addresses it: the absolute branch now returns the dirname as the splice prefix (with a single-slash special case at filesystem root), so Tab yields /var/www/newvillacarmen.
• Prevention: TestCommandCompletionAbsolute pins nested absolute completion, Tab-cycling prefix survival, and root-level tokens.

3. Flow

sequenceDiagram
    participant U as User
    participant CB as Command bar
    participant FS as Filesystem
    participant T as File tree
    participant F as Finder index

    U->>CB: Esc : cd /var/www/new + Tab
    CB->>FS: ReadDir(/var/www)
    FS-->>CB: matching directories
    CB-->>U: common prefix, then cycle
    U->>CB: Enter
    CB->>FS: Stat(target)
    FS-->>CB: valid dir
    CB->>T: rebuild at new root
    CB->>F: recreate + Rebuild (background)
    F-->>CB: finderRebuiltEvent
    CB-->>U: sidebar + finder point at new root

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Screenshots

Command bar with directory completion — suggestion popup above the input, match count on the right:

Absolute-path completion fix — /tmp/opencode/spicedemo/new + Tab completes the full path, not just the last segment:

After cd + Enter — the sidebar re-roots at the new directory (nvim :cd behavior), open tabs survive, and the status bar flashes the new root:

Sidebar Find-in-files panel — Files/Find tab strip, per-file accordions with match lines:

Terminal tab — a shell running inside an editor tab (Esc-` or the ≡ menu), file tree and terminal side by side:

New-terminal "+" button — pinned to the far right of the tab bar; clicking it opens a second terminal tab:

4. Changes

App (event loop / UI)

File	Change
internal/app/app.go	Tab-bar terminal button geometry, sidebar-tab and search state, command-bar routing in key/mouse/draw chains, reroot support wiring, menu row for the command bar.
internal/app/commandbar.go	New: command bar — input handling, bash-style directory completion (common prefix, cycling, ~/absolute/relative), cd validation, reroot of tree/finder/git status/search state.
internal/app/sidebarsearch.go	New: sidebar Find-in-files panel — query input, per-file accordion groups, click-to-jump, independent of the Esc-F modal.
internal/app/searchfiles.go	New: centered find-in-files modal the sidebar panel shares its grep backend with.
internal/app/diffviewer.go	New: git-changes modal — dirty-file list plus scrollable per-file unified diffs.
internal/app/leader.go	New Esc-leader bindings: : command bar, F find-in-files.
internal/app/modals.go	closeAllModals / anyModalOpen cover the command bar and new modals.
internal/app/find.go	Find bar no longer swallows keystrokes while the new surfaces own the keyboard.
internal/app/gitstatus.go	Exposes the repo root and status snapshot the diff viewer renders.

Editor / Finder

File	Change
internal/editor/terminal.go	New: PTY-backed terminal tab with resize and scrollback handling.
internal/editor/terminal_unix.go, internal/editor/terminal_windows.go	Platform PTY/ConPTY shims for the terminal tab.
internal/editor/tab.go	Tab kinds for terminals and image previews; keyboard routing opt-out for terminal tabs; far-right "+" new-terminal button geometry in the tab bar.
internal/editor/comment.go	Comment toggle no-op guard for non-text tabs.
internal/finder/grep.go	New: project grep producing content matches for both search surfaces.
internal/icons/icons.go	Terminal glyph for the tab bar.

Tests

File	Change
internal/app/commandbar_test.go	New: completion (single/common-prefix/cycle/nested/absolute/tilde), cd validation, re-root wiring, Esc-: routing, drawing.
internal/app/sidebarsearch_test.go	New: sidebar panel state and result grouping.
internal/app/searchfiles_test.go, internal/app/diffviewer_test.go, internal/app/terminal_test.go, internal/editor/terminal_test.go	New coverage for the find-in-files modal, diff viewer and terminal tabs.
internal/finder/grep_test.go	New: grep matching and gitignore behavior.
internal/app/app_test.go	Menu-layout geometry expectations updated for the new row.

Config / Docs

File	Change
README.md	Documents the command bar, sidebar search, terminal tabs and diff viewer.
go.mod, go.sum	PTY and gitignore dependencies for terminals and grep.
internal/version/version.go	Version bump to 0.0.44.

5. Verification

• go test -race ./... — all 12 packages pass on every commit (run before each fork PR merge).
• gofmt -l — no new unformatted files.
• go vet ./... — clean.
• Manual smoke (real terminal, tmux, 120x34): Esc-: opens the bar; cd /tmp/…/spicedemo/ shows 4 directory candidates; …/new + Tab completes the full absolute path; Enter re-roots the sidebar (see screenshots); clicking the Find tab and typing func returns 4 per-file accordions; Esc-` opens a terminal tab, the far-right "+" button opens a second one, and both shells accept input in parallel with the editor.
• Coverage of new UI logic: same-package tests beside every new source file, tcell.NewSimulationScreen for draw assertions, t.TempDir() for filesystem state.