Segment bar: stable clip numbers, scroll preservation, boundary-accurate playback

[morepriyam]

Fixes #126

What changed

Stable clip numbers

• New label column on segments, minted from a new monotonic last_clip_number counter on projects — assigned once when the clip is recorded/imported, never renumbered on reorder, gaps left by deletes are intentional. Shown as a small badge on each thumb, so "move 7 between 3 and 12" stays meaningful however the draft is shuffled. label is cosmetic metadata only — it is never part of the segment-set signature, so a future rename feature can't invalidate a merged transcript.
• Migration backfills existing rows from sort_order, dedupes any historically raced order values, seeds last_clip_number per draft, then adds a unique (project_id, sort_order) index (Add DB indexes (schema defines none) #64). The renumber step avoids SQLite window functions (no ROW_NUMBER()), so it runs on older bundled SQLite builds.
• addSegment computes order via max()+1 and mints label from last_clip_number inside one transaction — fixes the count() order race (recorder: stopRecording idempotency, cameraReady latch, segment-order race #96, item 3). reorderSegments renumbers in two bulk passes (park on negatives, then a single CASE update) so the unique index holds mid-update without per-row round-trips. .pulse imports renumber sequentially (a foreign bundle with duplicate orders can no longer abort the import).

Scroll ownership

• No more auto-scroll-to-newest — recording a clip never moves the bar; the user's scroll position wins.
• Delete preserves your place — the pre-delete offset is restored (clamped to the new content width) instead of snapping to the start.

Preview playback correctness + playhead polish

• Playhead boundary jank fixed: advancing (or tapping) to another clip left positionMs at the outgoing clip's near-end value for one render, so the knob jumped mid-thumb into the next thumbnail, then slid back to its left edge. Position is now reset in the same render as the selection swap — the knob lands exactly on the incoming thumb's left edge.
• Clips play to their true end: the timeUpdate handler advanced up to 60 ms before the out-point, cutting the last frames of every clip. Under the destructive-edit model the out-point is the file's end, so playToEnd (which always fires) is now the sole advance trigger.
• End of draft parks at the end (was: seeked to the START of the last clip while paused — the seek bug from player: gapless segment preview (preload next player) + end-of-draft seek bug + missing-file handling #97).
• Failed clip load can't wedge the session: replaceAsync(...).then(begin) now has a .catch that disarms the swap guards (also from player: gapless segment preview (preload next player) + end-of-draft seek bug + missing-file handling #97).

Tests

• The px↔ms track mapping is extracted to track-mapping.ts and unit-tested: draft start → x 0, draft end → last thumb's right edge, segment boundaries → incoming thumb's LEFT edge, proportional in-clip mapping, zero-length-clip skipping, px↔ms round-trip.

Scope notes

• Drag-to-trash is kept (decided against removing it for now); the gesture-audit item in Segment bar: simplify gesture surface, keep scroll position on delete, stable per-clip numbers #126 is otherwise resolved by the changes above.
• The dual-player gapless preload from player: gapless segment preview (preload next player) + end-of-draft seek bug + missing-file handling #97 is intentionally not part of this — separate change.

Manual test checklist

• Record 10+ clips, scroll to the middle, record another → bar does not move
• Delete a mid clip (preview → trash) → scroll position preserved
• Reorder far-apart clips → number badges unchanged
• Play through a whole draft → knob lands on each thumb's left edge at every boundary, no mid-thumb jump
• Last clip plays to its final frames; knob parks at the track's end; play again restarts
• Import a .pulse bundle → clips numbered 1..n in bundle order

Screenshots

Stable clip numbers — delete clip 2 of 5

Before (main: bar renumbers)	After (badge labels keep their numbers)

Scroll preservation on delete + stable numbers through reorder

ScreenRecording_07-26-2026.14-08-40_1.mov

[horner]

@morepriyam Do we have a test package? I want to be able to click a button and pull down 2-3 projects that we know to be simple, average, and complex. Average being 10-15 clips, Complex being like 80.

[morepriyam]

@horner Yes, locally. Dev builds have one-tap seed buttons on the library screen (src/dev/seed.ts) that build 4 purpose-built drafts from bundled fixtures:

1. Curated mixed (6 clips): mismatched portrait/landscape, 1080p/4k, 30/60fps, h264/hevc. The simple one.
2. Speed uniform (20 clips, ~2 min): 20x the recorder-match clip, exercises the passthrough fast path.
3. Speed mixed (20 clips): 14 recorder-match + 6 outliers, the average real-world case.
4. Wild imports (12 clips): one per hostile format (HDR 10-bit, 120fps slo-mo, VFR, WhatsApp baseline, screen-rec, no-audio, Opus, rotation variants, square, NTSC, mono 44.1k).

Seeding is idempotent, re-pressing is a no-op.

I haven't gone as high as 80. Long runs at that scale heat my phone up noticeably and repeated test runs take a real bite out of the battery. Can add a ~80 clip tier from the same fixtures if we want it, it just needs a device someone doesn't mind cooking.

[Copilot]

Pull request overview

This PR improves the recorder segment bar’s UX and the preview player’s boundary correctness while introducing a stable, per-clip creation ordinal in the DB so segment identity survives reorder/delete. It also extracts and tests the track px↔ms mapping used by the playhead cursor for more reliable boundary behavior.

Changes:

• Add created_ordinal to segments plus a unique (project_id, sort_order) index; update segment insertion/reorder/import paths to be race-safe and ordinal-stable.
• Preserve segment-bar scroll position on delete (and stop auto-scroll-to-newest on record) while updating the bar’s drag handle UI to display the stable ordinal badge.
• Fix preview playback boundary behavior (end-of-draft parking, boundary position reset, play-to-end advance) and extract track mapping math into unit-tested helpers.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/features/recorder/use-preview.ts	Playback boundary correctness, end-of-draft behavior, and swap error handling improvements.
src/features/recorder/track-metrics.ts	Adjust vertical lane metrics to accommodate the new ordinal/handle pill.
src/features/recorder/track-mapping.ts	New pure ms↔px mapping helpers extracted from the playhead cursor for testability.
src/features/recorder/track-mapping.test.ts	Unit tests covering draft/segment boundary mapping and round-trips.
src/features/recorder/segment-bar.tsx	Scroll preservation on delete, removal of auto-scroll-to-newest, and ordinal pill drag-handle UI.
src/features/recorder/playhead-cursor.tsx	Use extracted mapping helpers and tweak cursor line sizing/layout.
src/features/draft-transfer/unpack.ts	Ensure imported segments get sequential createdOrdinal after sorting to satisfy unique order index.
src/db/schema.ts	Add createdOrdinal column and unique index definition for (projectId, order).
src/db/legacy-migration.ts	Backfill createdOrdinal for legacy draft migration inserts.
src/db/drafts.ts	Transactional max()+1 order/ordinal assignment and two-pass reorder to satisfy the unique index.
drizzle/migrations.js	Register the new Drizzle migration.
drizzle/meta/0011_snapshot.json	Drizzle schema snapshot update reflecting the new column and index.
drizzle/meta/_journal.json	Drizzle journal update for migration 0011.
drizzle/0011_segment_ordinal.sql	Migration to add/backfill created_ordinal, dedupe/renumber sort_order, and add unique index.

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[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

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[Copilot]

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[horner]

This is a really good PR. I love the screenshots.

[morepriyam]

301ac80 adds forward-looking schema support for user-renamable clips: a nullable label column on segments plus migration 0012_segment_label (ALTER TABLE segments ADD label text;, no backfill needed — NULL = unnamed).

Design notes:

• label sits alongside created_ordinal as cosmetic identity: reorder/delete never touch it, and the UI is expected to fall back to the ordinal badge when unnamed.
• It's excluded from the segment-set signature, so renaming a clip can never invalidate a merged transcript.
• No reads/writes yet — the rename UI, renameSegment helper, and draft-transfer pack/unpack support are intentionally left for a follow-up.

Type-check and full test suite pass (119 tests).

[Copilot]

Pull request overview

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Pull request overview

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Pull request overview

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Pull request overview

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Comments suppressed due to low confidence (1)

src/db/schema.ts:50

• The PR description (and linked issue notes) still describe a new created_ordinal column on segments, but the shipped schema implements stable clip identity via projects.lastClipNumber + segments.label. Please update the PR description to match the actual schema (or rename the columns to match the documented concept) so future migrations/data-debugging don’t have two competing models for “stable clip numbers.”

  // Monotonic badge counter: the highest clip number ever minted for this draft. Bumped on
  // every clip added, never decremented — so deleting (or renaming) a clip can never cause
  // its number to be reused.
  lastClipNumber: integer('last_clip_number').notNull().default(0),

[morepriyam]

The tests are done on a physical device again after the changes, ready to merge