librarian/docs/debug_log.md

Debug Log

A running log of notable bugs fixed in Librarian, newest first. Add new entries at the top. Each entry records the symptom, the root cause, how it was fixed, and the files/lines touched, with the commit that carries the fix for context.

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2026-06-17 — Inline rename could rename the WRONG file after a background refresh

Commit: 18318c7 — "Code Review fixes" (branch feat-phase2)

Symptom

Start an inline rename (F2) on a file, then — before pressing Enter — let the open folder change on disk (an external tool adds/removes/renames a sibling, e.g. an editor's temp/.lock churn). Pressing Enter renames a different file than the one whose name is being edited. Silent data corruption.

Root cause

Rename stored only { index, value } — a positional row index. The folder watcher fires DirChanged → Reloaded, whose recompute_rows() re-sorts and rebuilds self.rows. After the re-sort, renaming.index points at whatever file now occupies that row, and RenameCommit did self.rows.get(state.index) and renamed that row's target. The same positional-index hazard scrambled the selection during a streaming search: SearchBatch re-sorts every batch but — unlike Reloaded — did not re-map the selection, so a click / Delete made mid-stream acted on the wrong hit.

Fix

Carry file identity, not row position, across a recompute:

• Rename gained a path: PathBuf captured at RenameStart; RenameCommit renames that path (and derives the old name from it), ignoring the possibly-stale index.
• SearchBatch now captures selected_paths() before recompute_rows() and calls restore_selection() after, exactly as the Reloaded arm already did (re-select by path).

Affected files & lines

crates/librarian-app/src/main.rs:

• L192–202 — Rename: added the path identity field (doc'd why index can go stale).
• L1616–1628 — RenameStart: capture the lead path into Rename.path.
• L1635–1655 — RenameCommit: rename state.path, not rows[index].
• L2071–2076 — begin_pending_rename: set path for a programmatic rename.
• L1137–1160 — SearchBatch: capture/restore selection by path across the re-sort.

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2026-06-17 — Background refresh / stale landing list clobbered the visible view

Commit: 18318c7 — "Code Review fixes" (branch feat-phase2)

Symptom

Two related glitches:

1. Run a search in a folder; while results show, anything changes the folder on disk → the results vanish, replaced by the normal folder listing, and the search silently stops streaming.
2. From "This PC", open a drive and immediately navigate into a folder. The slow drive-list enumeration finishes after you've arrived and overwrites the folder with the "This PC" drive grid, dropping the loading overlay early.

Root cause

Both are "a stale/background producer clobbers the current view":

1. Reloaded's success arm set self.content = Content::Folder { entries } unconditionally — even with Content::Search on screen. The search subscription was still alive, so subsequent SearchBatches were then dropped (content no longer Search).
2. ThisPcLoaded / WslLoaded carried no load token, so a slow list_drives result applied even after a newer navigation. (Last session's F2 guarded the reverse direction — navigating away from a virtual root — by bumping the token in load_current; this is the other half.)

Fix

• Reloaded (Ok) bails when Content::Search is active, and DirChanged skips the read entirely during a search — the search owns the screen; clearing it re-reads the folder fresh.
• ThisPcLoaded / WslLoaded now carry the load token (captured when load_current dispatches list_drives / list_wsl_distros) and drop on mismatch.

Affected files & lines

crates/librarian-app/src/main.rs:

• L606–607 — ThisPcLoaded / WslLoaded: added a u64 load-token field.
• L1192–1210 — handlers: drop on token mismatch.
• L1247–1252 — DirChanged: skip the refresh while a search is active.
• L1275–1281 — Reloaded (Ok): don't overwrite an active Content::Search.
• L1792–1812 — load_current (ThisPc / Wsl): capture and tag the load token.

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2026-06-17 — Review hardening: overlay lock, tab session reset, config & grid guards

Commit: 18318c7 — "Code Review fixes" (branch feat-phase2)

Summary

Lower-severity fixes from the same comprehensive review:

• Modal-overlay total-lock gaps — ViewModeChanged, SortBy, and SearchDebounced bypassed the loading overlay's input lock (a floating pick_list dropdown or a deferred search debounce could fire during a cold load and release the lock early). Added them to is_input_shortcut. → main.rs L3578–3586.
• New tab inherited a stale thumbnail session — reset_flat didn't clear overlay_loading / thumb_token / bg_queue, so a new tab could show the previous tab's spinner and keep pumping its background thumbnail queue. reset_flat now supersedes the session. → main.rs L843–849.
• Non-finite persisted column width — a corrupt nan / inf entry in the columns config parsed to a valid f32 and pushed a NaN width through compute_col_px into iced layout (f32::clamp returns NaN unchanged). decode_rule now rejects non-finite values (+ regression test). → columns.rs L119–131.
• Grid window arithmetic — visible_thumb_keys computed row * cols before clamping; switched to saturating_* so an extreme stale scroll_y can't overflow a usize or invert the slice range (matches the window_for hardening in afd23ed). → main.rs L2370–2376.
• De-duplicated name comparison — hoisted the triplicated case-insensitive name compare into librarian_core::cmp_name_str, now called by the folder, search-results, and tree-children sorts (a single point to later switch to StrCmpLogicalW). → sort.rs L77, lib.rs L19, main.rs search/tree sorts.

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2026-06-17 — WSL folder load: column "pinch" + inconsistent loading screen

Commit: 20347e3 — "WSL loading screen fix" (branch feat-phase2) The fix is confined to crates/librarian-app/src/main.rs. That commit also bundles unrelated in-flight phase-2 work (rows.rs, model.rs, sort.rs, lib.rs, docs/phase2_simplify_review.md) — those files are not part of this fix.

Symptom

Navigating into a WSL folder (e.g. \\wsl.localhost\Ubuntu\...) showed a different loading experience than thumbnail loading: the details-view columns visibly pinched to their minimum widths and then snapped back when the listing arrived, and there was no spinner overlay. On fast local folders this flashed by; over WSL's slow 9P network reads it sat on screen long enough to be jarring.

Root cause

Two unrelated loading paths existed:

• Thumbnail loading used a modal overlay (loading_overlay): a rotating spinner + "Loading…" on a semi-transparent scrim drawn over the existing grid, so nothing reflowed.
• Folder loading (load_current) instead blanked the list immediately — set Content::Folder { loading: true }, cleared rows, and reset col_measure to default. With no rows to measure, the auto-fit columns collapsed to MIN_COL_W (the pinch), and no overlay was shown during the directory read at all. The nice overlay only ever appeared later, for the thumbnail phase.

Fix

Unified folder loads onto the same modal overlay, and kept the previous folder on screen (dimmed, under the overlay) instead of blanking — which removes the pinch:

• load_current (the Path branch) no longer touches content/rows/columns. It raises overlay_loading and a new per-tab load_pending flag, then kicks off the read. The previous folder stays visible under the spinner.
• Message::Loaded clears load_pending, then adopts the new folder's column layout and resets col_measure (deferred from navigation), swaps in the entries, and hands off to the thumbnail session. In details view the overlay simply releases onto correctly-sized columns; in grid views it carries into thumbnail loading.
• load_pending replaced the old Content::Folder { loading } marker (which only existed to blank + later resume a mid-load tab), so that field was removed. The flag is parked/restored per tab via TabState.
• Edge case covered: a disk-change refresh (Message::Reloaded) landing mid-navigation now fulfills the pending load (adopts columns, clears the flag) instead of leaving it stuck.

Because all navigation (back/forward/up/refresh/tree/address) routes through load_current, the unified overlay + no-pinch behavior applies everywhere.

Affected files & lines

crates/librarian-app/src/main.rs:

• L299–301 — Content::Folder: removed the loading: bool field.
• L408–413 — Librarian struct: added the per-tab load_pending: bool field.
• L450–454 — updated the overlay_loading doc comment (now covers folder reads).
• L521 — TabState: added load_pending: bool.
• L695 — new(): init load_pending: false.
• L771 — snapshot_flat: park load_pending.
• L792 — restore_flat: restore load_pending.
• L823 — reset_flat: reset load_pending = false.
• L898–901 — show_active: resume a mid-load tab via if self.load_pending.
• L1169–1205 — Message::Loaded: clear load_pending (L1173), adopt columns (L1178–1179), drop the loading field, release the overlay on the error path.
• L1216–1231 — Message::Reloaded: mid-navigation guard (std::mem::take, L1226), drop the loading field.
• L1677–1735 — load_current: removed the eager column reset; landing-page arms (ThisPc/Wsl) reset columns to default; the Path branch keeps the previous folder and raises load_pending (L1729) + overlay_loading (L1730).
• L2492–2493 — empty_list_message: key the "Loading…" placeholder off load_pending (only seen at startup / fresh tabs, where there is no previous folder).