#139 feat(sessions): shorten titles from the middle, window lines to the match

Summary

Session-finding §4.5 — row readability (plan: docs/session-finding-plan.md). Follows PR #137. The custom title is this app's primary way to tell sessions apart — the user hand-titles every non-throwaway session — and it was the least readable thing in the row.

The measurement that reframed this

Taken from the reference machine's 125 unique custom titles:

Median title length	44 chars — against a 35-char cut
Longer than the cut	64%
Written as A -> B > C chains, newest step at the END	38%
Titles sharing their first 35 characters	48 of 125
Largest such group	8 sessions, all rendering as fred-ff nextjs backend and mcp arch

The last row is the point: this was never mainly a search problem. 38% of titles were ambiguous while simply browsing, because head-only truncation removes exactly the segment that distinguishes one session from the next.

What changed

1. Titles shorten from the middle — truncateMiddle(text, 60) giving head … tail, so a chain keeps its newest step:

before   fred-ff nextjs backend and mcp arch
after    fred-ff nextjs backend and mc…ive > canva debug

The budget went 35 → 60. That number is a starting point, not a conclusion — it needs looking at against the real window, and is expected to move.

2. The full title is on a title= attribute. Previously there was no way to read a long title at all; now hovering shows it.

3. Searching moves each line's window to the match. windowAroundMatch() shifts a capped line so the first match is inside it, with ellipses marking what was cut. Applied through one fitToRow() helper to the title, first and last message, branch, and last AI reply — one rule, six call sites.

This is the other half of the same defect: a row would satisfy the filter and then display nothing explaining why. Measured — 39% of first prompts and 42% of last prompts are longer than the space they render in.

4. Issue #138 — the matched-prompt line no longer reads as a message line. It used #999, the same grey as the first-message line, one pixel smaller, and its ⌕ marker (U+2315) is illegible at 11px — reported as • and then ρ by the person who asked for the feature. It is now amber, in the same family as SEARCH_HIGHLIGHT_STYLE, with a worded match #N marker.

Implementation notes

Both helpers are pure and live in session-search.ts beside extractSnippet, so they are unit-testable without the renderer. The row calls them through a single fitToRow(text, max) closure that picks match-windowing while a search is live and middle-truncation otherwise — the alternative was six call sites each deciding for themselves, which is how the last PR's bugs happened.

One thing deliberately not changed: §4.5's R3, where the ⌕ line is suppressed when the match lands in prompt #0 or the last prompt even though those lines are themselves capped. It needs no separate fix — once those lines window to the match, suppressing the duplicate is correct again. R3 was a symptom of the missing window, not an independent bug.

npx tsc --noEmit clean. Prettier: the two touched pure modules are fully formatted; in switcher-ui.tsx only the line breaks this PR introduced are fixed, per docs/session-finding-plan.md §7.11 — that file carries over a thousand pre-existing violations and no CI lint gate.

Tests

82 pass (+8). Mutation-verified rather than assumed:

Reverted	Result
truncateMiddle → plain head slice	2 failed / 80 passed
windowAroundMatch → always fall back	2 failed / 80 passed
(restored)	82 passed

The load-bearing case asserts two titles that are identical for 35 characters render differently after truncation — the browsing failure above, expressed as a test.

How to test (yarn make)

1. Long titles — a chain-style title should now show its tail; the eight fred-ff nextjs backend and mcp arch sessions should be distinguishable at a glance.
2. Hover a shortened title → the tooltip shows the whole thing.
3. Search for a word that appears late in a title (or late in a first message) → the line should shift so the highlight is visible, with a leading ….
4. Search for a word near the start → the line should look exactly as it does when not searching (no needless shifting).
5. match #N line — search for something in a middle prompt; the line should read as amber with a labelled marker, clearly not another message line.
6. Width check — 60 chars is a guess at what fits. If titles now crowd the badges, say so and it moves.

Follow-ups

• The 60-char budget, pending the look in step 6.
• Branch stays on line 1 in this PR. Moving it to line 2 would give it permanent room but is a visible layout change, deliberately not bundled here.

Closes #138.

🤖 On behalf of @grimmerk — generated with Claude Code

---

Summary by cubic

Shortens long session titles from the middle and windows capped lines to include a visible match, so each row shows why it matched. Previously titles were head-truncated to 35 and matches could be hidden; now titles render as a 60‑char head … tail with a tooltip, and search shifts each capped line to include a match without overrunning its cap.

• Implements truncateMiddle(text, 60) and windowAroundMatch() in src/session-search.ts; a single fitToRow in src/switcher-ui.tsx applies them to the title, branch, first/last user message, and last assistant reply.
• Matching uses one rule: find matches case-insensitively via toLowerCase() exactly as matchesAllWords, then translate offsets back to the source so highlights align, including Unicode folding and matches that begin inside a folding expansion; query words are literals, not regex.
• If the ordinary rendering already shows a later occurrence, keep it; otherwise window to the earliest hit. Long matched words are kept whole (or shown from their first character if longer than the window). Budgets include ellipses and are always honored; tiny budgets (≤2) fall back.
• Matched-prompt line: neutral grey text with an amber “match #N” chip matching the highlight color. Hovering a shortened title shows the full title.
• Tests: 94 cover cap enforcement, Unicode folding/offset translation (including mid-expansion starts), earliest‑vs‑visible occurrence behavior, and long‑word handling.
• Note: the 60‑char title budget may need tuning if it crowds badges.

Summary by CodeRabbit

• Improvements

  • Long session titles and related text now preserve meaningful beginnings and endings when shortened.
  • Search results show match-centered windows across titles, branches, prompts, snippets, and responses.
  • Full titles remain available through tooltips.
  • Search snippets now use clearer amber, bold “match #N” indicators for easier navigation.

• Bug Fixes

  • Improved matching for repeated occurrences and Unicode text in search results.
  • Reduced duplicate or irrelevant snippet displays.

• Documentation

  • Updated release documentation for version 1.0.86.