Review Diff Mode -- Combined UX Report

Sources:

• claude/audit-review-diff-mode-nGTV4 -- UX Audit & Bug Report
• claude/test-review-diff-mode-7xnTV -- Manual Testing Bug Report

Date: 2026-04-10 Editor version: Fresh 0.2.22 (debug build, commit 9ab13b3) Test environments: tmux, 120x35 and 160x45 terminals, Linux 4.4.0

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Executive Summary

Two independent UX testing sessions were conducted on Review Diff mode. After cross-referencing and deduplicating, 9 distinct bugs were identified, sorted below from most dangerous to least.

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Bugs by Criticality

Tier 1 -- Hangs / Unrecoverable State

BUG-5: Side-by-Side Drill-Down Hangs for Deleted Files

Field	Value
Criticality	HANG
Reported in	Bug Report #3
E2E test	test_bug5_deleted_file_drill_down_hangs

Pressing Enter on a deleted file shows "Loading side-by-side diff..." indefinitely. The user is stuck -- no timeout, no error, no way out except closing the tab. This is the only bug that produces a UI hang.

Root Cause: review_drill_down() calls editor.readFile(path) for the new version. For a deleted file the file doesn't exist, readFile returns null, the function exits early but the "Loading..." status persists and the view is never created nor cleaned up.

Fix: Detect deleted-file status before calling readFile. Show OLD content on the left and an empty pane on the right. Clear the loading status on error.

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BUG-2: Terminal Resize Destroys Review Diff Layout (Unrecoverable)

Field	Value
Criticality	UNRECOVERABLE CORRUPTION
Reported in	Bug Report #2
E2E test	test_bug2_resize_destroys_review_diff_layout

Resizing the terminal while in Review Diff mode causes the toolbar, header, separator, and content to disappear. The layout does not recover even after resizing back. Neither r (refresh) nor navigation keys restore it. Pressing Home causes diff content to render below the status bar.

Fix: The resize event handler must trigger a full re-layout of all Review Diff panels. The design doc specifies listening to the resize event but this path is broken.

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Tier 2 -- Entire Feature Surface Broken

BUG-1: CompositeInputRouter Is Dead Code -- Side-by-Side Keyboard Nav Broken

Field	Value
Criticality	FEATURE INOPERABLE
Reported in	Audit #3, Audit #4, Bug Report #6
E2E tests	test_bug1_side_by_side_vim_keys_produce_editing_disabled, test_bug1_side_by_side_escape_does_not_close, test_bug1_side_by_side_tab_does_not_switch_pane

All vim-style keys (j/k/Tab/n/p/Escape) in the side-by-side diff view produce "Editing disabled in this buffer". Only q and arrow keys partially work.

Root Cause: CompositeInputRouter (crates/fresh-editor/src/input/composite_router.rs) implements the full routing but is never called from app/input.rs. Key events fall through to the standard text-editing path, which rejects them.

Fix: In app/input.rs, after mode binding resolution, check if the active buffer is composite. If so, route through CompositeInputRouter::route_key_event() and dispatch the RoutedEvent. The code is already written and unit-tested -- it just needs to be connected.

Also resolves: BUG-9 (viewport scroll).

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Tier 3 -- Silent Failures (Features Don't Work, No Error)

BUG-3: File Explorer Steals Focus from Review Diff on Launch

Field	Value
Criticality	SILENT FAILURE
Reported in	Audit #1, Bug Report #1
E2E test	test_bug3_file_explorer_steals_review_diff_keys

When File Explorer is open (default state), opening Review Diff does not transfer focus. All review-mode keybindings silently fail -- j triggers the File Explorer's quick-search instead.

Workaround: Ctrl+E toggles focus, but this is not discoverable.

Fix: In start_review_diff(), explicitly move focus to the review diff files panel after creating the buffer group.

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BUG-4: Hunk Navigation (n/p) Non-Functional in Diff Panel

Field	Value
Criticality	SILENT FAILURE
Reported in	Audit #5, Bug Report #4
E2E test	test_bug4_hunk_navigation_n_does_not_move_cursor

Pressing n/p in the diff panel does nothing. No error, no movement. Other review-mode keys (c, s, u, d) work from the same panel, so the mode bindings are resolving -- the handler logic itself is broken.

Root Cause candidates:

1. state.hunkHeaderRows empty (not populated for current file)
2. state.diffCursorRow not updated by programmatic cursor moves
3. Stale byte offsets causing jumpDiffCursorToRow() to silently bail

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BUG-6: Comments from Files Panel Never Display Inline

Field	Value
Criticality	SILENT DATA LOSS (visual)
Reported in	Bug Report #5
E2E test	test_bug6_comment_from_files_panel_not_visible_in_diff

Comments added from the files panel are stored but never rendered inline in the diff view. The user thinks the comment was saved (status bar says "Comment added") but it's invisible. Comments ARE stored in the session file, so no actual data loss, but the user cannot see or interact with them in the UI.

Root Cause: getCurrentLineInfo() returns no line-level info when the files panel is focused. pushLineComments() skips comments without line_type/old_line/new_line.

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BUG-9: Down Arrow Doesn't Scroll Viewport in Side-by-Side View

Field	Value
Criticality	SILENT FAILURE
Reported in	Bug Report #6
E2E test	test_bug9_side_by_side_down_arrow_no_viewport_scroll

In side-by-side diff, pressing Down updates the status bar line number but the viewport stays frozen at the top.

Note: Symptom of BUG-1. Likely resolved once CompositeInputRouter is wired.

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Tier 4 -- UX Annoyances / Missing Keybindings

BUG-7: Escape Does Not Exit File Explorer Focus

Field	Value
Criticality	UX GAP
Reported in	Audit #2
E2E test	test_bug7_escape_does_not_exit_file_explorer_focus

When the File Explorer has focus, pressing Escape does nothing. Users must know Ctrl+E to escape. Minor, but compounds with BUG-3 to make the first-use experience confusing.

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Tier 5 -- Cosmetic

BUG-10: Toolbar "Export" Label Truncated with File Explorer Open

Field	Value
Criticality	COSMETIC
Reported in	Bug Report #8
E2E test	test_bug10_toolbar_export_label_truncated

With the File Explorer sidebar open, the toolbar's e Export hint is truncated to e E or missing entirely.

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Features Verified Working (Both Reports Agree)

Feature	Status
File list navigation (j/k/Up/Down/Home/End/PageUp/PageDown)	Working (after focus is correct)
File list boundary clamping	Working
Tab focus toggle (files <-> diff)	Working, robust under rapid toggling
s (stage file/hunk)	Working
u (unstage file/hunk)	Working
d (discard) with confirmation dialog	Working
r (refresh)	Working
c (comment) prompt	Working (but inline display broken -- BUG-6)
N (note)	Working
x (delete comment)	Working
e (export to markdown)	Working
Enter (drill-down to side-by-side)	Working (except deleted files -- BUG-5)
Side-by-side diff layout and alignment	Working
Horizontal scrolling in side-by-side	Working
Long line handling	Working
q (close)	Working
Diff coloring (added/removed/context/word-level)	Working
Section headers (Staged/Changes/Untracked)	Working

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Prioritized Fix Order

Order	Bug	Criticality	Effort	Rationale
1	BUG-5	Hang	Low-Med	Only hang in the feature. Deleted file drill-down traps the user.
2	BUG-2	Unrecoverable	Med-High	Terminal resize destroys UI with no recovery path.
3	BUG-1	Feature inoperable	Medium	Highest ROI: one wiring change unlocks all side-by-side keyboard nav. Also fixes BUG-9.
4	BUG-3	Silent failure	Low	Auto-focus on launch. One-line fix, eliminates first-use confusion.
5	BUG-4	Silent failure	Medium	Hunk nav is a core workflow feature.
6	BUG-6	Silent data loss	Medium	Comments are stored but invisible.
7	BUG-9	Silent failure	Low	Likely fixed by BUG-1. Verify only.
8	BUG-7	UX gap	Low	Escape to leave File Explorer.
9	BUG-10	Cosmetic	Low	Toolbar label truncation.