#6706 fix(desktop): recover the Files tab from listings that fail during a host outage

Problem

Customer report (the "right sidebar is a complete mess" feedback): the Files tab doesn't refresh when switching projects until a manual refresh, folders won't open, files won't open.

The v2 failure mode, reproduced deterministically over CDP: a directory listing that fails during a workspace switch (host-service restarting, relay flap) is never retried, leaving the Files tab permanently empty. The Refresh button can't recover it — doRefresh only re-lists already-loaded directories, and after a failed initial load there are none, so it issues zero requests (confirmed via console logs). A Refresh clicked mid-outage even commits the empty result and wipes a previously loaded tree.

Fix (all in useFilesTabBridge.ts)

• Failed listings retry with bounded exponential backoff (1s→15s, 5 attempts); the root always qualifies, other dirs only while still known and expanded.
• doRefresh always re-lists from the root, so it can bootstrap an empty tree.
• doRefresh aborts without committing on transport-level failures (isHostServiceConnectionError); typed errors (NOT_FOUND) still drop a genuinely deleted directory.
• When the host connection (re)opens, re-fetch the unloaded root and any expanded dirs still awaiting children — covers outages that outlast the backoff window.

Verification

A/B over CDP against the dev app, identical journey (Files tab loaded → hold host-service down 30s via SIGKILL loop → switch workspace mid-outage → let the host respawn):

tree rows	during outage	host back +25s	Refresh ×2
before	0	0 — stuck	0 — no requests sent
after	0	45 — self-healed, no clicks	45 kept during a fresh outage

Also verified unaffected happy paths still work: workspace switch A→B→A, lazy subfolder expansion, file open, external folder rename while expanded, create-then-rename bursts.

bun test (2706 desktop tests), typecheck, and biome all pass.

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Summary by cubic

Recovers the Files tab after host outages by retrying failed directory listings and letting Refresh bootstrap from the root. Previously, a listing failure during a workspace switch left the tab empty; Refresh sent no requests and could commit an empty tree.

Key changes

• Retries failed listings with bounded exponential backoff (1s–15s, max 5). Root always eligible; nested dirs only if still known and expanded.
• Refresh always re-lists from the root and aborts committing on transport-level failures; typed errors (e.g., NOT_FOUND) still remove genuinely deleted dirs.
• On host connection open, re-fetches the unloaded root and any expanded dirs awaiting children.
• Clears per-dir failure counts on success and on workspace switch. All changes are contained in useFilesTabBridge.ts.

Summary by CodeRabbit

• Bug Fixes
  • Improved file and folder loading reliability after temporary connection failures.
  • Added automatic retries for failed directory listings, including expanded folders and the workspace root.
  • Prevented incomplete file results from appearing when the host connection is unavailable.
  • Cleared outdated loading errors after successful refreshes and workspace changes.