Prev/Next navigation in expanded block view

[Shayshez]

Summary

Screen.Recording.2026-09-10.at.18.54.00.mov

• Adds Prev/Next chevrons (and Left/Right arrow key shortcuts) to the
  block detail header so you can step through adjacent blocks in the
  same lane without closing back to the chain gallery each time.
• Reuses the existing detailBlockId prop-swap mechanism already
  exercised by swap-tone (same blockId, new tone) rather than any new
  unmount/remount boundary, so it doesn't touch [Feature]: Retain chain scroll position when closing expanded block view #82/[Feature]: Retain chain scroll position when adding new block #114's scroll-restore
  work at all.
• Stepping is lane-local and skips insert slots, clamped at the lane's
  ends (no wraparound); a branch only taps the signal into the other
  lane, it never reorders or merges the two arrays, so this is correct
  in stereo too regardless of branching.
• Both chevrons and the arrow-key shortcut disable while a model switch
  is in flight (switchModel has no cancel handle, so a step mid-switch
  is ignored rather than left to race), and the arrow listener ignores
  keydowns while an input/textarea/select/editable element has focus so
  it doesn't fight normal typing or dropdown navigation.
• showEq/eqView deliberately survive a step (not reset) so you can
  compare EQ curves block to block — but the EQ body otherwise looks
  identical regardless of which block it's showing, so a step left no
  visible sign of which block you landed on. Fix: a small tone-title
  label in the shared card header, shown only while the EQ view is open
  (the non-EQ body already shows the title prominently). It reads
  straight off the tone prop, so it updates automatically on every
  step with no new state or effect.

Depends on #115 (issue #82's scroll-restore fix): this branch is
based on feature/chain-scroll-restore rather than main directly,
since this change extends the exact onBack code path #115 rewrote.
Until #115 merges, this PR's diff includes its commit too — that's
expected for a stacked PR, not a mistake.

Fixes #83

Test plan

• ./script/test-dsp.sh — 140/140 tests pass on this branch
• tsc -b / eslint clean on the changed files
• Full plugin build (Release, Standalone) succeeds
• Manually verified in a freshly built Standalone: Prev/Next chevrons
  and arrow keys step correctly, disable at lane boundaries, and the
  EQ header shows the current block's title while stepping

🤖 Generated with Claude Code

[woodybury]

@Shayshez LGTM couple notes:

please rebase with the edits i made to scroll position
i'd rather just hide left/right arrows when viewing the EQ

[Shayshez]

Hey @woodybury
while working through this navigation problem, I ended up prototyping a different approach: instead of prev/next chevrons, a persistent strip showing the whole chain (block types, empty insert slots, bypass state) that you can click into directly from any position - no stepping through one block at a time.

Chain-Map.mov

Quick demo attached - if this direction looks good to you, I'd extract just this feature cleanly onto its own branch off main before opening a PR. (Note: this is running on my personal experimental branch with several other features I'm trying out)

I think this solves the underlying problem this PR is aiming at more completely, and also connects to #84 (chain view real estate) as an alternative way to keep the chain visible while working inside a block. Happy to clean this up and open it as its own PR if you think it's a better direction than the chevrons here - otherwise happy to leave this PR as-is, your call.

[woodybury]

@Shayshez neat i'll share this with our designer and get thoughts. since this is a bigger chain will likely take some design iteration

[Shayshez]

@woodybury

Recorded another clip showing more progress on this: quick access to the EQ (at the bottom of each chip), drag-to-reorder, and double-click to toggle bypass. Also added scrolling support for when the chain gets long.

Makes a real difference for usability and speed once you've got more than a few blocks stacked up. It also hooks into the tooltip bar at the bottom of the plugin, so hovering a block always shows its name there (same as everywhere else in the UI).

ChipsUI.mov