fix(tui): clear sticky currentFile pill when agent activity is quiet

[kelsonpw]

Summary

Salvaged from #738 by cherry-picking its unique commit onto a fresh branch from main. The original PR was stacked on the closed feat/v2-tui-redesign (#696); its git history carried ~35 commits of v2 orchestration scaffolding that couldn't be rebased onto main's parallel orchestration implementation.

Original commit preserved: fc8bc468

Test plan

• tsc clean
• eslint clean
• pnpm build clean
• CI will run vitest + Bugbot

Generated with Claude Code

---

Note

Low Risk
Low risk: only adjusts TUI rendering logic for the “currently editing” indicator and adds focused tests; no auth/data-flow changes.

Overview
Fixes the Progress tab’s sticky “currently editing …” pill so it stops claiming the agent is editing a file after activity has ended.

RunScreen now clears the last shown filename when either (a) the most recent fileWrites entry is terminal (applied/failed) and older than the new STALE_FILE_WRITE_MS grace window, or (b) post-agent steps begin (postAgentSteps.length > 0). Adds a new vitest suite covering in-flight display, stale-time clearing, immediate clearing on post-agent steps, and “heartbeat” behavior when new writes arrive.

^{Reviewed by Cursor Bugbot for commit e580915. Bugbot is set up for automated code reviews on this repo. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

Bugbot Autofix prepared a fix for the issue found in the latest run.

• ✅ Fixed: Tests assert on nonexistent "editing " prefix from missing component
  • Added the missing "editing " prefix to the current-file pill rendering in RunScreen.tsx (line 504), making the component output match what the tests assert on — positive assertions now correctly verify the pill is visible, and negative assertions genuinely validate that clearing works.

Or push these changes by commenting:

@cursor push 2cfe09d64b

Preview (2cfe09d64b)

diff --git a/src/ui/tui/screens/RunScreen.tsx b/src/ui/tui/screens/RunScreen.tsx
--- a/src/ui/tui/screens/RunScreen.tsx
+++ b/src/ui/tui/screens/RunScreen.tsx
@@ -501,7 +501,7 @@
             </Box>
             {currentFile && (
               <Text color={Colors.muted} wrap="truncate-end">
-                {currentFile}
+                editing {currentFile}
               </Text>
             )}
           </Box>

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^{Reviewed by Cursor Bugbot for commit a184ff9. Configure here.}