feat(ui): remove top-level Changes tab, keep session-level d diff

[senamakel]

Summary

Removes the top-level Changes tab from the TUI. A Git diff is a property of one session — what it changed since it launched — not a view over the whole fleet, so it now lives only at the session level: press d on a session row in the Sessions tab to swap the harness terminal for that session's launch diff; d/Esc swaps it back.

What changed

Removed (the tab surface):

• "Changes" from both TABS arrays (workflows build 8→7, slim build 7→6) — src/tui/src/ui/app/types/model.rs
• the "Changes" => draw_changes render dispatch arm, the Changes hint line, and the "Changes" => "Diff" compact tab label — render/mod.rs
• the if tab == "Changes" key-dispatch arm and its refresh_changes on tab-enter — keys/mod.rs, state.rs
• the capital D shortcut from the Sessions rail (it jumped to the now-gone Changes tab) — keys/sessions.rs
• open_selected_harness_changes (dead with the tab gone) and the dead draw_changes tab wrapper — changes/mod.rs, render/changes.rs

Kept (the session d path — unchanged behavior):

• toggle_harness_diff_pane and draw_harness_diff → draw_changes_into, the render path the Sessions tab already used
• the shared GitChangesState, on_changes_key bindings (↑↓ files, j/k line, [/] hunk, b baseline, c/C/e comments, r refresh)
• the SDK-side git_review model

Both access paths already shared this state, so the session d pane retains the full review surface — only the top-level tab and its D shortcut were removed.

Tests:

• Removed shift_d_on_a_selected_harness_opens_its_changes_tab (tested the removed D).
• Removed the two compact_tab_label("Changes", …) assertions.
• Rewrote the oversized-diff-line wrapping tests to render via draw_harness_diff (the remaining path) instead of the removed tab arm.
• Reworded the Changes section of the in-app keyboard help to describe d on a session row.

Configuration / API changes

None. No public API, config, or persistence change — purely a TUI surface removal.

Validation

cargo build
cargo clippy --all-targets -- -D warnings
cargo fmt --check
cargo test

All green, zero test failures.

🤖 Generated with Medulla

Summary by CodeRabbit

• Navigation
  • Removed the standalone Changes tab from the main navigation.
  • Git diffs now open directly from a session row using lowercase d.
• Diff Viewing
  • Added a two-pane diff view with baseline selection, file and comment details, and improved scrolling for long changes.
  • Press d or Esc to return to the harness terminal.
• Usability
  • Updated keyboard help and improved focus when entering Hosts.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 7b681c45-fc05-46c3-97ba-fceecbb1a56f

📥 Commits

Reviewing files that changed from the base of the PR and between 4ab56c9 and c6b5e57.

📒 Files selected for processing (3)

• src/tui/src/ui/app/render/tests.rs
• src/tui/src/ui/app/state.rs
• src/tui/src/ui/app/types/model.rs

🚧 Files skipped from review as they are similar to previous changes (3)

• src/tui/src/ui/app/state.rs
• src/tui/src/ui/app/render/tests.rs
• src/tui/src/ui/app/types/model.rs

---

📝 Walkthrough

Walkthrough

The standalone Changes tab was removed from tab lists, key handling, rendering, and state entry logic. Git diff access remains in the Sessions harness pane through draw_harness_diff, with updated help text and tests.

Changes

Session diff navigation

Layer / File(s)	Summary
Remove standalone Changes tab src/tui/src/ui/app/types/model.rs, src/tui/src/ui/app/changes/mod.rs, src/tui/src/ui/app/keys/*, src/tui/src/ui/app/render/mod.rs	The Changes tab, its tab lists, navigation method, key handling, rendering dispatch, and shortcut labels were removed.
Route diff access through sessions src/tui/src/ui/app/state.rs, src/tui/src/ui/app/changes/mod.rs, src/tui/src/ui/app/render/settings/help.rs	Hosts focus is initialized during tab entry. Harness diff access uses the Sessions pane. Help text describes session-row d navigation and d or Esc for return.
Update diff validation src/tui/src/ui/app/render/tests.rs, src/tui/src/ui/app/tests/harness_pane.rs	Rendering tests now use the harness diff path. Obsolete standalone Changes-tab assertions were removed.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Suggested labels: severity: low

Suggested reviewers: tinysweeper

Poem

I’m a rabbit in Sessions, quick and bright,
I press d to view the diff in sight.
The old Changes tab hopped away,
Harness panes now guide the way.
Back with d or Esc—goodnight!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes removing the top-level Changes tab while retaining session-level diff access with the d key.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

---

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[coderabbitai]

🧹 Nitpick comments (2)

src/tui/src/ui/app/render/tests.rs (1)

138-140: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Move these imports to the module import group.

Keep ChangedFile, tab_pos, and PaneView with the file-level imports. Do not declare imports inside app_on_an_oversized_diff_line.

As per coding guidelines, “Keep imports grouped at the top of Rust source files.”

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/tui/src/ui/app/render/tests.rs` around lines 138 - 140, Move the
ChangedFile, tab_pos, and PaneView imports into the file-level import group at
the top of the test module, and remove their local import declarations from
app_on_an_oversized_diff_line.

Source: Coding guidelines

src/tui/src/ui/app/types/model.rs (1)

76-83: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Document the non-workflow TABS constant.

The documentation at Lines 55-61 applies only to the workflow-enabled constant. Add equivalent /// documentation before Line 76.

As per coding guidelines, “Every public Rust item—including functions, types, traits, fields, and variants—must have a /// documentation comment.”

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/tui/src/ui/app/types/model.rs` around lines 76 - 83, Add a `///`
documentation comment immediately before the public non-workflow `TABS`
constant, documenting the tabs it exposes and matching the equivalent
workflow-enabled `TABS` documentation.

Source: Coding guidelines

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@src/tui/src/ui/app/render/tests.rs`:
- Around line 138-140: Move the ChangedFile, tab_pos, and PaneView imports into
the file-level import group at the top of the test module, and remove their
local import declarations from app_on_an_oversized_diff_line.

In `@src/tui/src/ui/app/types/model.rs`:
- Around line 76-83: Add a `///` documentation comment immediately before the
public non-workflow `TABS` constant, documenting the tabs it exposes and
matching the equivalent workflow-enabled `TABS` documentation.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: c4e0c2a8-a681-4d11-8d7e-f4d9467e5212

📥 Commits

Reviewing files that changed from the base of the PR and between 1e8a255 and 4ab56c9.

📒 Files selected for processing (10)

• src/tui/src/ui/app/changes/mod.rs
• src/tui/src/ui/app/keys/mod.rs
• src/tui/src/ui/app/keys/sessions.rs
• src/tui/src/ui/app/render/changes.rs
• src/tui/src/ui/app/render/mod.rs
• src/tui/src/ui/app/render/settings/help.rs
• src/tui/src/ui/app/render/tests.rs
• src/tui/src/ui/app/state.rs
• src/tui/src/ui/app/tests/harness_pane.rs
• src/tui/src/ui/app/types/model.rs

💤 Files with no reviewable changes (4)

• src/tui/src/ui/app/keys/sessions.rs
• src/tui/src/ui/app/keys/mod.rs
• src/tui/src/ui/app/render/mod.rs
• src/tui/src/ui/app/render/changes.rs

[tinysweeper]

tinysweeper found nothing blocking. Approving.

             $0.0075 · 148,878 in / 10,997 out · 93,296 cached (63%) · openrouter/openai/text-embedding-3-small, z-ai/glm-5.2 · 560 embedded
critique:    $0.0032 · 65,032 in  / 8,119 out  · 55,697 cached (86%) · z-ai/glm-5.2
security:    $0.0036 · 63,038 in  / 1,338 out  · 19,003 cached (30%) · z-ai/glm-5.2
tests:       $0.0005 · 14,298 in  / 1,180 out  · 12,868 cached (90%) · z-ai/glm-5.2
description: $0.0002 · 6,510 in   / 360 out    · 5,728 cached (88%)  · z-ai/glm-5.2

[tinysweeper]

What this change touches

10 files, +74 -100 across 7 components. It reaches 6 untouched components (60 graph nodes walked). 12 further components left out to keep the diagram readable.

flowchart LR
  n0["src/tui/src/ui/app/changes<br/>1 file +17 -32"]:::changed
  n1["src/tui/src/ui/app/render<br/>3 files +19 -24"]:::changed
  n2["src/tui/src/ui/app<br/>1 file +21 -16"]:::changed
  n3["src/tui/src/ui/app/types<br/>1 file +14 -4"]:::changed
  n4["src/tui/src/ui/app/tests<br/>1 file +1 -15"]:::changed
  n5["src/tui/src/ui/app/keys<br/>2 files +0 -8"]:::changed
  n6["src/tui/src/ui/app/render/settings<br/>1 file +2 -1"]:::changed
  n7["src/tui/src/ui/app/changes<br/>2 files reached"]:::impacted
  n8["src/link/src<br/>1 file reached"]:::impacted
  n9["src/sdk/src/mcp<br/>1 file reached"]:::impacted
  n10["src/sdk/src/mcp/tools<br/>1 file reached"]:::impacted
  n11["src/sdk/src/ui/git_review<br/>1 file reached"]:::impacted
  n12["src/sdk/tests/support<br/>1 file reached"]:::impacted
  n1 -->|8 refs| n11
  n1 -->|6 refs| n8
  n1 -->|6 refs| n9
  n1 -->|5 refs| n3
  n2 -->|5 refs| n3
  n4 -->|5 refs| n3
  n5 -->|5 refs| n3
  n1 -->|4 refs| n12
  n6 -->|4 refs| n3
  n2 -->|3 refs| n11
  n4 -->|3 refs| n2
  n1 -->|2 refs| n10
  n2 -->|2 refs| n8
  n3 -->|2 refs| n8
  n5 -->|2 refs| n8
  n6 -->|2 refs| n8
  n7 -->|2 refs| n3
  n1 -->|1 ref| n6
  n2 -->|1 ref| n1
  n2 -->|1 ref| n4
  n2 -->|1 ref| n5
  n2 -->|1 ref| n7
  n4 -->|1 ref| n8
  n7 -->|1 ref| n8
  classDef changed fill:#0d4429,stroke:#238636,color:#e6edf3
  classDef impacted fill:#161b22,stroke:#6e7681,color:#c9d1d9
  classDef flagged fill:#5a1e02,stroke:#d93f0b,color:#ffffff
  classDef blocking fill:#67060c,stroke:#f85149,color:#ffffff

Loading

_{Green: changed. Grey: untouched, reached through an import or a call. Orange: has findings. Red: has a finding that blocks the merge.}

Component		Files	Lines	Findings
src/tui/src/ui/app/changes	changed	1	+17 -32	—
src/tui/src/ui/app/render	changed	3	+19 -24	—
src/tui/src/ui/app	changed	1	+21 -16	—
src/tui/src/ui/app/types	changed	1	+14 -4	—
src/tui/src/ui/app/tests	changed	1	+1 -15	—
src/tui/src/ui/app/keys	changed	2	+0 -8	—
src/tui/src/ui/app/render/settings	changed	1	+2 -1	—
src/tui/src/ui/app/changes	reached	2	—	—
src/link/src	reached	1	—	—
src/sdk/src/mcp	reached	1	—	—
src/sdk/src/mcp/tools	reached	1	—	—
src/sdk/src/ui/git_review	reached	1	—	—
src/sdk/tests/support	reached	1	—	—

Changed files

src/tui/src/ui/app/changes

• src/tui/src/ui/app/changes/mod.rs

src/tui/src/ui/app/render

• src/tui/src/ui/app/render/changes.rs
• src/tui/src/ui/app/render/mod.rs
• src/tui/src/ui/app/render/tests.rs

src/tui/src/ui/app

• src/tui/src/ui/app/state.rs

src/tui/src/ui/app/types

• src/tui/src/ui/app/types/model.rs

src/tui/src/ui/app/tests

• src/tui/src/ui/app/tests/harness_pane.rs

src/tui/src/ui/app/keys

• src/tui/src/ui/app/keys/mod.rs
• src/tui/src/ui/app/keys/sessions.rs

src/tui/src/ui/app/render/settings

• src/tui/src/ui/app/render/settings/help.rs