fix av switch hiding branches in tall stacks

[simsinght]

Reported on Discord: in a 12-branch stack in a ~20-row terminal, av switch only showed av-stack-04 and below (and no header), but the hidden branches were still selectable.

Bubbletea v2's inline renderer drops the top lines of any frame taller than the terminal, and av switch rendered the whole tree without handling WindowSizeMsg. The tree now scrolls to keep the selected branch on screen, with the header and help line always visible. When the tree fits, output is unchanged.

Also accepts esc to cancel av switch, and its help line now says esc cancel. Other prompts are unchanged since they still only accept ctrl+c.

Adds stackutils.RenderTreeWithLineRanges so the view knows which lines each branch occupies; RenderTree output is unchanged.

Follow-up, not in this PR: adopt_tree_selector likely has the same tall-tree issue.

Tested: TestSwitchViewScrollsToChosenBranch (fails on master: 41 lines vs a 20-row limit), TestSwitchViewEscCancels, and manually in a 20-row tmux pane with the reported stack.

Summary by CodeRabbit

• Usability
  • The branch switch screen now keeps the selected branch visible as you navigate, including when the terminal is resized.
  • Press Escape or Ctrl+C to cancel switching.
  • The screen displays contextual status information and help for its available controls.

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✅ FlexReview Status

Common Owner: aviator-co/engineering (expert-load-balance assignment)
Owner and Assignment:

• ✅ aviator-co/engineering (expert-load-balance assignment)
  • Slack: #fr-eng-notifications
  • Assigned: jainankit
  Owned Files

  • 🔒 cmd/av/switch.go
  • 🔒 cmd/av/switch_test.go
  • 🔒 internal/utils/stackutils/render_tree.go

Review SLO: 7 business hours if PR size is <= 200 LOC for the first response.

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ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Organization UI
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• Run ID: b5001bad-7f24-481f-89ee-f633eb43920e

📥 Commits

Reviewing files that changed from the base of the PR and between 6a11f1e and 43eba41.

📒 Files selected for processing (3)

• cmd/av/switch.go
• cmd/av/switch_test.go
• internal/utils/stackutils/render_tree.go

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📝 Walkthrough

Walkthrough

The switch view now keeps the selected branch in the visible tree viewport, updates the viewport on navigation and resize, and accepts Escape as a cancel key. The tree renderer can return line ranges for rendered branches.

Changes

Switch view

Layer / File(s)	Summary
Track rendered branch line ranges internal/utils/stackutils/render_tree.go	RenderTreeWithLineRanges returns the rendered tree and a line range for each branch. The existing RenderTree uses the renderer without range tracking.
Keep the selected branch visible cmd/av/switch.go, cmd/av/switch_test.go	The switch view uses branch ranges to limit the tree to the visible viewport and adjusts its scroll offset on navigation and resize. Escape and Ctrl+C both cancel. Tests check branch visibility while scrolling and cancellation with Escape.

Priority: ⬇️ Low

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

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant KeyInput
  participant SwitchViewModel
  participant RenderTreeWithLineRanges
  participant TerminalView
  KeyInput->>SwitchViewModel: Send selection or resize message
  SwitchViewModel->>RenderTreeWithLineRanges: Render tree and collect branch ranges
  RenderTreeWithLineRanges-->>SwitchViewModel: Return tree lines and branch ranges
  SwitchViewModel->>TerminalView: Display visible tree lines and help bindings

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Suggested reviewers: tulioz

Merge Risk: ⚪ Minimal · up to 43eba

No confirmed issue blocks merging after normal checks.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 8 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 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 the main change: fixing hidden branches in av switch for tall stacks.
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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