reasampler/docs/PLAN.md

# PLAN

The post-1.0 roadmap. Seventeen queued items consolidated into overlapping areas and
sequenced into a Phase → Wave → Track hierarchy that implementation specialists can be
dispatched against directly — **plus Phase Γ**, which did not come from those seventeen
(it came from a direct interview, 2026-08-01) and is scoped in
`docs/product/instrument-control-surface.md`.

## What this doc is, and how it relates to the others

- **`docs/PLAN.md`** (this file) — the active on-deck specification list. Each track is
  written so a specialist brief is writable from this file alone: goal, consolidated
  source items, surface boundary, behavior, acceptance criteria, open questions,
  prerequisites.
- **`docs/TODO-1.0.md`** — retained as the **verbatim-provenance appendix**. It holds
  Daniel's raw asks and every answer round, unedited; where this plan compresses a
  behavior bullet, that file is the backing record. Items are cited here by number
  (e.g. "consolidates items 1, 8, 14"). It is not a work queue any more; this file is.
- **`docs/TODO.md`** — deferred follow-ups with recorded rationale, unrelated to the
  seventeen (with one flagged intersection: see "Flagged for awareness" below).
- **`docs/COMPLETED.md`** / **`docs/ARCHIVE.md`** — doc-keeper's. When a track here
  finishes, its point is removed from this file and appended to `COMPLETED.md` with any
  deviation between landed code and spec noted.
- **`docs/product/`** — the product-design reasoning behind prior phases. Grep for a
  cited section rather than reading a file whole.

**Worktree slug convention:** `p<phase>-w<wave>-t<track>-<slug>`. Greek phase letters
transliterate: **Θ → `th`**, **Ξ → `xi`**, **Γ → `g`**. So Θ-W1-T1 dispatches into
`pth-w1-t1-zone-retirement` and Γ-W1-T1 into `pg-w1-t1-knob-interaction-law`.

## Decision state

Everything carried forward from `TODO-1.0.md` is classified **[verify]** (answerable by
reading code or running the DAW) or **[propose]** (a design call made at implementation
review with a proposal, not a Daniel call); that classification is preserved per
question, attached to the track that will answer it.

Θ-W3-T1's two genuine **[Daniel]** questions — which no amount of code-reading could
answer — are both ruled on and the track has landed; see `docs/COMPLETED.md` for the
full narrative. **Reload tier = Grouping B** (continuous knobs live: filter cutoff/Q/
morph/drive/mod amount/key-track, every envelope stage time and level; root note, loop
span, and start frame still trigger a full reload). **Mid-stage rule = candidate (iv),
hold normalized stage position** (φ = elapsed/duration held fixed across a duration
change, then advancing at 1/newDuration). **Phase Γ opened five [Daniel]-class forks (Γ-F1…Γ-F5) and all five are ruled** (Daniel,
2026-08-01) — the rulings are folded into the tracks below and indexed in
`docs/product/instrument-control-surface.md` §8.1. **One new fork, Γ-F6, is open**: it was
surfaced by the Γ-F2 ruling out of the vendored VST3 SDK, and Daniel has not seen it. It sits
on Γ-W1-T2, is **not blocking** — it is gated on a DAW measurement that track performs first
— and it has a pre-agreed fallback. No other track in this plan carries an unanswered
**[Daniel]**-class question.

### Flagged for awareness — not blocking, but decision-grade

1. **Item 15 has an unresolved cross-artifact seam, and it is the phase's largest
   unknown.** The instrument is a read-only bank consumer by invariant
   (`src/shell/instrument/CLAUDE.md`), and the one previous attempt at an
   instrument→extension relay (S13) closed with a **DEGRADED** spike verdict and was
   deferred (`docs/TODO.md`). Resample requires that crossing. Ξ-W2-T1 opens with the
   architecture decision and this plan names the candidates rather than assuming the
   deferred relay shape; see that track. Consequence to hold: if every candidate fails
   verification, item 15's "one click from inside the VST" framing is what gives, not
   the read-only invariant — the fallback is a bindable extension-side action.

2. **Phase Γ must land before Ξ-W2, and this is a correctness point, not a preference.**
   Ξ-W2's settled reset scope enumerates parameters by name; Γ adds rate, pitch offset and
   the limiter flag, so shipping the bake first means its reset list is incomplete on the
   day it lands. Γ's product doc pre-classifies all three against the ratified rule (all
   **reset**), so this costs no Daniel decision — only ordering. Second, weaker reason: Γ
   owns params-payload v14 and v15, and Ξ-W3's programmed-signal persistence will want the
   next rung; two phases contending for the ladder is the fight Θ's organizing constraint
   exists to avoid.

3. **The taper work inside Γ-W1-T1 is a one-way door with respect to automation.** Once
   VST3 parameters exist, the taper *is* the host-facing normalization, and re-tapering
   re-interprets every recorded automation point in project files we do not own and cannot
   migrate. Re-tapering is free today and permanently expensive afterwards. See
   `docs/product/parameter-automation.md` §4 — that doc is scoping only, nothing in it is
   scheduled here. **The same door applies to the stage-time ceiling**, which Γ-F3 left at
   2.0 s with a 10 s ambition recorded in `docs/TODO.md`: if that ceiling is ever raised, it
   wants to happen before the parameter system, not after.

## Phase-wide acceptance criteria

These bind every track in all three phases and are stated once here rather than repeated
per track. **Phase Γ adds five of its own**, stated in its phase header.

### Structural (root `CLAUDE.md`, Daniel 2026-07-28)

- **More directories is a must; more files is good; ~600-line file ceiling.** The
  ceiling is the *bar*; a responsibility seam is the *method*. Bisection-to-hit-the-
  number is rejected. `sampler_core.cpp` (956 lines) is the standing documented
  hot-path exception — Θ-W1-T1 re-seams it, and any surviving over-ceiling TU must
  carry the same explicit justification.
- **Templates where earned** — compile-time dedup with zero runtime cost, off the hot
  paths. Not for types that differ in name only.
- **SOLID is great, but saved CPU is better.** No dispatch-stack blowouts anywhere;
  prefer static polymorphism where the types are compile-time-known.

### Performance guardrails

Root `CLAUDE.md`'s five extension-side guardrails (peaks envelope compute, audition,
realtime-capture tick, JSON, `FxBypassGuard`) are unchanged by this plan; no track here
touches them. The instrument adds a sixth surface that binds every Θ track:

- **`process()` — the per-voice-per-sample path — takes no new indirection.** The
  filter tick, the envelope evaluation (staged *and* spline), the pitch-shift read, and
  the loop read all sit on it. Concrete, inlineable types only: **no `IEnvelope`, no
  `IFilter`, no virtual per-voice `tick()`**. A filter with two modes is a
  branch-predictable switch or a compile-time-known dispatch, never a vtable. Spline
  evaluation is a binary search over a point array, not a polymorphic curve object.
- **No allocation, no file I/O, no bridge call in `process()`.** The off-audio-thread
  `reloadInstrument` + atomic pointer swap stays the only way new state reaches the
  audio thread. Every new parameter this plan adds follows that path.
- **A split that would add a hot-path indirection is out of scope — rework it or drop
  it.**

### Product invariants

- **Capture and placement are separate acts.** No track here may place a timeline item.
  Item 15's bake explicitly must not, and one of its candidate architectures uses a
  *temporary* arrange mutation — that candidate must leave the arrange byte-identical.
- **Prune is the single, exclusive file-deletion authority.** Item 15's "replace" never
  deletes bytes; item 17's consolidation may not weaken any protection prune has today.
- **The instrument never writes the bank.** Item 15 is the first feature that needs to,
  and it resolves that by *asking the extension*, not by breaching the invariant.
- **Migration bar: a project saved before a change reopens sounding identical.** Holds
  everywhere except item 16's genuinely-multi-zone case, where Daniel deliberately
  relaxed it.
- **Every pure module gets a `<module>_tests` target** that runs without REAPER or a
  DAW. New pure modules in this plan are not optional-test.

---

## Phase Θ — ReaSampler 9000: one parameter set, a filter, shapeable envelopes, a legible editor

**Ships:** the instrument with the zone system retired, a resonant HP/LP filter stage in
the voice path, curve-shapeable and spline-drawable envelopes on all three EGs,
Gate-mode loop sustain, and a re-laid, high-DPI-clean editor — plus the two extension
drag/drop defects that block getting captures into it.

**Consolidates items** 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16.

**All seven waves have landed — Phase Θ is complete.** W1 through W7 each carry their own
landed note above; see `docs/COMPLETED.md` for every track's full narrative. Θ-W7 was
opened after Θ-W6-T1 shipped, to fix two rendering defects Daniel found by eye; it did not
exist in the plan when this phase was originally scoped.

**The organizing constraint.** Three surfaces in the instrument are single-writer by
nature and dictate the wave shape:

1. **The parameter model** (`zone_params.h` + `component_state_io`) — every parameter
   addition touches both. Two tracks adding parameters concurrently is a merge fight
   and two competing `ComponentState` version bumps.
2. **The voice render path** (`sampler_core.cpp`) — filter insertion, envelope
   evaluation, loop read, and the Trigger tail all live there.
3. **The Sample face** (`editor_paint_sample.cpp` 516 lines / `editor_input_sample.cpp`
   583 lines) — every UI item repaints it, and both are already at the ceiling.

Parallelism in this phase therefore comes from **splitting the Sample face into bands**
(done once, in Θ-W1-T1) and from **extension-side work being genuinely disjoint** — not
from running two parameter-model tracks at once. Where a wave has one track, the
collision is real and the serialization is the correct answer.

---

### Θ-W1 — Collapse and re-seam

**All three tracks have landed** — Θ-W1-T1 (`zone-retirement`), Θ-W1-T2
(`capture-handoff-bugs`), and Θ-W1-T3 (`filter-dsp-port`) — see `docs/COMPLETED.md` for
the full narrative of each. Between them: the zone subsystem is retired, the wave's two
responsibility seams (the `sampler_core` split, the Sample-face band split) are in
place, the two extension-side capture-handoff defects are fixed, and the filter DSP has
landed as a standalone pure module — Θ-W2-T1 has since wired it into the voice path (see
below).

---

### Θ-W2 — Filter in the voice path; waveform and chrome bands

**Depends on W1 for:** the one-parameter-set model and the `sampler_core` seam that T1
writes the filter into; the `filter` module T1 wires up; the Sample-face band split and
band-stack allocator that T2 and T3 fill; and W1-T1's key-range answer, which decides
what T3's piano strip displays. Authoring any of this against the per-zone model means
writing storage plumbing W1 deletes.

**All three tracks have landed** — Θ-W2-T1 (`filter-voice-path`), Θ-W2-T2
(`stereo-waveform-lanes`), and Θ-W2-T3 (`toolbar-and-piano-strip`) — see
`docs/COMPLETED.md` for the full narrative of each. Between them: the filter sits in the
per-voice signal path with its own deck, the waveform band shows both channels in
stereo mode behind a type-enforced full-height overlay contract, and the chrome band's
toolbar and piano strip are cleaned up per spec. The three tracks were disjoint by
band — T1 owned the parameter model and the deck band, T2 owned the waveform band, T3
the chrome band — and none re-allocated the band stack.

---

### Θ-W3 — Live parameters, then the staged envelope system

**Depends on W2 for:** the filter envelope's existence — items 1, 8, and 14 govern
*three* envelopes, and the filter is the third; and for the Filter deck, which must
exist before it can receive a corner radio switch and inner curve dials. T1 additionally
depends on W2-T1 for the filter itself: the filter is the first control set where the
latched-at-note-on delivery model fails audibly, and it is what made the defect visible.

**Both tracks have landed** — Θ-W3-T1 (`live-parameter-delivery`) and Θ-W3-T2
(`staged-envelope-curves`) — see `docs/COMPLETED.md` for the full narrative of each.
Between them: every continuous playback control (filter cutoff/Q/morph/drive/mod
amount/key-track, every stage time and level on all three envelopes) now reaches a
sounding voice live instead of latching at note-on, and the envelope-overlay editor
grew from an amp-only fixture into the shared graphical surface for all three
envelopes — a corner radio switch per deck (none active by default), curve-shapeable
segments on every sloped stage (0.1–10 exponent, an inner dial paired with an overlay
knot), the release-right-anchored AHDSR layout against the pitch envelope's 1:1 AHD,
and the Trigger amp/filter fade pair folded into a Trigger AHD, consolidating what
were two staged-shape mechanisms into one. The Trigger × Preserve end-of-sample click
is fixed; the landed fix is wider than scoped, also ringing out Gate × Preserve ×
source-exhaustion, previously a hard cut. The ordering was deliberately serial — T1's
live-delivery mechanism landed first so T2's new curve exponents and Trigger AHD
fields were authored directly into it rather than backfilled afterward.

---

### Θ-W4 — Loop sustain and the velocity deck

**Depends on W3 for:** the envelope system both tracks compose with — T1's loop-sustain
is the Gate-mode sustain the AHDSR releases out of, and T2's bipolar pitch/filter curves
modulate targets whose envelopes W3 just reshaped. T2 additionally depends on W2-T1 for
the filter's existence and on W2-T3 for the preview button's toolbar position.

**Both tracks have landed** — Θ-W4-T1 (`gate-loop-sustain`) and Θ-W4-T2
(`velocity-deck-and-bipolar-curves`) — see `docs/COMPLETED.md` for the full narrative of
each. Between them: loop points are now a usable feature, with a Gate-mode loop acting
as the sustain and a parameterized crossfade at the seam; and the three velocity-curve
popups (amp, pitch, filter) now live together in a new VELOCITY deck group, with the
pitch and filter curves bipolar and flat-by-default so their modulation is off until
drawn, while the amp curve stays unipolar and unchanged, and the preview button's text
is replaced by a drawn play-triangle glyph. Params payload reached v11 with T1's loop
block and v12 with T2's velocity→pitch curve appended after it.

---

### Θ-W5 — Spline EGs

**Depends on W4 for:** the bipolar velocity-curve domain (W4-T2) — the spline algorithm
is **singly implemented and multi-referenced**, so its enhancement must land against the
final consumer set, and the last consumer to change domain is the pitch/filter velocity
curve; and for the Gate-mode loop (W4-T1), since "Gate is unavailable in Spline mode" is
only a real, testable rule once Gate has something to be unavailable *for*. It also
depends on W3's radio switch, which is how a spline contour reaches the overlay at all.

**Θ-W5-T1 has landed** — `spline-egs` — see `docs/COMPLETED.md` for the full narrative.
It shipped a free-drawn alternative to every staged envelope: pitch, filter, and amp
EGs can switch Staged → Spline and have their contour drawn directly on the waveform
overlay. The one shared monotone-spline implementation gained hard points — sharp
corners, no smoothing on either adjacent segment — flowing to every consumer including
the existing velocity→amp transfer curve, no fork. Both Staged and Spline state persist
simultaneously (saved-but-inactive, lossless round-trip); params payload reached v13,
and v12 projects still load. Gate is unavailable while a Spline EG is active; the
contour is a pure time function over the full sample length, normalized and drawn 1:1
with the sample's time axis. Point grammar converged on left-click add / right-click
delete / control-click hard-smooth toggle, one grammar across both spline consumers.
Staged segment knobs and their inner curve dials render disabled and reject edits while
Spline is active. Point-count ceiling: 128, a musical bound rather than a performance
one. A follow-on change in the same track reworked deck cell width: `-1` in `cellIds`
now means one cell's width, reserved and redistributed, rather than a blank cell holding
geometry — a Trigger face that drops Sustain and Release gets wider cells instead of
dead slots; group widths, row packing, deck height, and Gate-mode cell widths are
unchanged.

---

### Θ-W6 — Editor legibility pass

**Depends on W5 for:** the last change to a drawn surface. Item 13 is an audit whose
output is a disposition list over "every class of drawn surface," and item 10's sizing
pass is judged by eye over the finished layout — running either while the spline contour,
the disabled-knob state, or the deck inventory was still moving would have meant
auditing and then re-auditing. Θ-W5-T1 has landed (see `docs/COMPLETED.md`), so that
surface has stopped moving and this dependency is satisfied. The source doc names this
sequencing as an observation (item 13 after the layout/knob work); this plan adopts it
as the boundary.

**One track.** Both items repaint essentially every surface in the editor; concurrent
tracks would collide everywhere.

**Θ-W6-T1 has landed** — `legibility-and-antialiasing` — see `docs/COMPLETED.md` for the
full narrative. It shipped both halves together: knobs grew 28→40 px (inner curve dial
14→20), the deck cell 48×58→60×74, and the label band 12→16 px, now drawn in
`Font::Label` rather than `Font::Micro` — group captions and toggle segments deliberately
stayed `Font::Micro`, since bumping them would outgrow row 1's headroom at the floor
width. The editor's default/minimum size grew 840×620→980×680 to fit the wider deck at
floor width; an existing saved instance's window grows on open, and the floor is
validated by a derived test rather than literals. All fourteen time-constant labels now
read in ms (display-only; internal representation untouched) — `holdFraction` knobs,
`Len %`, and the bank panel's duration readout stayed out of scope. Double-click resets
each ring independently — outer ring resets the value, inner dial resets the exponent to
1.0 — reaching the chrome's preview-velocity knob too via a shared `inKnobFace` rule.

The antialiasing audit fixed knob arcs and needle, the inner dial arc and needle, staged
and spline envelope slopes, the spline contour, the velocity-popup trace, the waveform
outline, and the preview triangle; node handles, curve knots, knob discs, buttons, piano
keys, loop markers, borders, gradients, and text were already clean. The disposition
table is a standing artifact in `docs/product/visual-design-language.md` §8. The
piano-key open question is answered: not aliasing — every key is an axis-aligned
`LICE_FillRect`, so the earlier width defect was integer-division residue in the tiling,
not a sloped edge. High-DPI host scaling itself is unverified (deferred, see
`docs/TODO.md`).

All visual outcomes remain pending Daniel's by-eye sign-off on `dev`.

---

### Θ-W7 — Arc-and-spline antialiasing fix

**Depends on W6 for:** a drawn surface to find a defect on — this wave did not exist in
the plan; it was opened after Daniel found two rendering defects by eye once Θ-W6-T1
shipped, so the audit's own output is what surfaced them.

**One track.**

**Θ-W7-T1 has landed** — `arc-and-spline-aa` — see `docs/COMPLETED.md` for the full
narrative. The stacked-`LICE_Arc` knob and dial rings never reached an opaque core (peak
alpha measured 138/255), and the staged/spline envelope and velocity-curve traces were
fully aliased rather than gapped, from integer `cy` quantizing the slope. Both defects,
plus the two needles, now route through one pure analytic thick-stroke rasterizer —
coverage in a new `core/ui/stroke_aa`, the single LICE blend in a new
`shell/instrument/editor_stroke` — replacing `LICE_Arc` and `LICE_ThickFLine` outright.
Measured: arc peak alpha 138/255 → 255/255, arc perpendicular-weight ripple 67% → 5%,
spline weight ripple 29% → 3%, at a cost of +0.09 ms per full editor repaint. Daniel then
ruled every sub-2 px stroker width up to 2 px, since the stroker only guarantees an
opaque core at width ≥ 2 px; the knob track arc, the inner-dial needle, and the deck's
mini velocity trace each moved 1.0 → 2.0 px. `docs/product/visual-design-language.md` §8
is corrected — a false "keeps every ring antialiased" claim is deleted, the rows are
re-dispositioned with measurements, and the audit's methodological lesson (verifying
which primitive was called is not verifying what it rasterized) is recorded as a standing
blockquote. All visual outcomes remain pending Daniel's by-eye sign-off on `dev`.

---

## Phase Ξ — The resample loop

**Ships:** one consolidated, fully robust provenance/usage tracking system, and on top of
it the one-click in-sampler resample — dial → bake → dial again, with the bank as the
medium each iteration passes through.

**Consolidates items 15, 17.**

**Why these two and not more.** Item 17 is a **prerequisite of meaning** for item 15's
bank-side half: the replace-vs-add rule is "does provenance-tied usage exist," which
denotes nothing until the consolidated lineage records exist. Item 17 is otherwise
independent of the editor chain — which is what makes Ξ-W1 concurrency-safe with Θ.

**Ξ-W2 onward requires Phase Θ complete.** Item 15 presupposes the processing surface it
bakes — "filtering, pitching, amp all set up nice" is the instrument items 1, 2, 3, and 14
build — and its settled reset scope enumerates the filter parameters, the spline contours,
and the loop points by name. Baking a processing chain that does not exist yet is not a
schedule preference; the feature is not expressible. Phase Θ landed as of Θ-W7-T1 (see
`docs/COMPLETED.md`); this gate is satisfied.

---

### Ξ-W1 — Consolidated tracking, and the programmed-note model

#### Ξ-W1-T1 — `tracking-consolidation`

**Landed** — see `docs/COMPLETED.md` for the full narrative. The provenance/usage
territory is now one system: a new `src/core/tracking/` directory holds `origin_ledger`
(the record family — `OriginRecord`/`OriginKind`, the insertion-ordered `OriginLedger`,
its JSON codec, and the `Fresh`/`Loaded`/`Unreadable`/`FutureVersion` load
classification) and `tracking_authority` (the one decision surface: `pruneProtection`
and `tiedUsageExists`), retiring `core/model/owned_manifest`. Both prune's protected set
and the resample's replace-vs-add decision are computed from one borrowed
`TrackingState`, so the two safety-critical consumers cannot drift apart.
`sample_usage` deliberately **stays in `core/wire`** — the consolidation is of the
decisions, not the codecs. The deferred persisted-instance-identity fix was **not**
folded in — the deferral is restated in `docs/TODO.md`, its one home. This track
landed `OriginRecord`'s birth-time `parentSampleId` chain as the lineage mechanism, but
**Ξ-W2-T1's "naming and lineage" open question (jointly held with this track) is
unaffected and still theirs to close** — display naming and user-readable iteration
lineage were not decided here.

#### Ξ-W1-T2 — `note-program-model`

**Landed** — see `docs/COMPLETED.md` for the full narrative. The programmed-capture-
signal model is a new pure module directory, `src/core/instrument/note/` — a fourth
peer of `engine/`/`map/`/`ui/` under `core/instrument/` — holding `musical_division`,
`tempo`, and `note_program` (`Velocity`, the denominated `OffsetAmount`, the anchored
`StartOffset`/`EndOffset`, `NoteProgram`, `resolveNote`). **Both open questions below
are answered, for Ξ-W3-T1:** negative offsets are legal in both directions (sign
uniform, positive is later in time; only an inverted window is refused, reported via
`ResolvedNote::windowCollapsed`), and the denomination seam is confirmed — note length
stays musical-division-only, and an offset stores the denomination it was entered in.

---

### Ξ-W2 — The bake chain

**Depends on Ξ-W1 for:** the consolidated lineage records that make replace-vs-add
computable (T1) and the programmed-note record the offline pass renders (T2). **Also
depends on all of Phase Θ** — see the phase note above.

**One track.** The bake is one gesture and one chain; the architecture decision at its
head governs every step after it.

#### Ξ-W2-T1 — `resample-bake-chain`

**Goal.** One click bakes the dialed sound into a bank capture, re-points the instance at
it, and hands the instrument back at neutral — the dial → bake → dial-again loop, run
without leaving the sampler.

**Consolidates item 15 (the chain; the popup UI is Ξ-W3-T1).**

**Surface boundary — owns:** whichever seam the architecture decision selects (see below),
plus `shell/capture/capture_orchestrator` (a resample entry point alongside
`captureAndIndexOne`), `core/model/bank_model` + `owned_manifest` at the add boundary,
`shell/actions` (a new action, if the decision needs one), and the instrument-side bake
trigger. **Does not own** the capture-signal popup's UI — that is Ξ-W3-T1.

##### The architecture decision — this track's first deliverable, before any chain work

Item 15 requires a click **inside the VST3 editor** to cause a **bank write**, and the
instrument is a read-only bank consumer by invariant. The one prior attempt at this
crossing (S13) closed **DEGRADED** and was deferred. Resolve this before building the
chain. Two orthogonal choices:

**Decision 1 — how the click crosses to the extension.**
- **(1a) Ext-state request key + extension-side timer poller**, with a claim/clear nonce —
  the shape S13 spiked and deferred. It needs a new instrument WRITE seam into ext-state,
  though the `rsusage_`-prefixed guarded write already establishes the precedent that such
  a seam can exist without weakening the read-only-*bank* invariant. Known cost: the
  cross-process handshake race the S17 spec rejected.
- **(1b) Direct action invocation over the VST-host bridge — the lead candidate.** A
  REAPER-hosted VST3 already resolves REAPER API functions **by name** over the host
  callback (that is how the instrument reads `GetProjExtState`), and can fetch its own
  host context — the track/take/project it was instantiated in. If `NamedCommandLookup`
  and `Main_OnCommand` resolve the same way, the editor can invoke the extension's bake
  action **synchronously**, with no request key, no poller, and no nonce — which dissolves
  the S13 problem for this case rather than re-litigating it. **[verify]** against
  `vendor/reaper-sdk/sdk/` (`reaper_plugin.h`, `video_processor.h`,
  `reaper_plugin_functions.h`) that both resolve over the callback, and that calling them
  from the editor's UI thread is safe. This is a verification task, not an assertion — do
  not build on it until confirmed.
- **(1c) No crossing — a bindable extension-side action only.** Fallback. It abandons
  Daniel's "from directly inside the ReaSampler 9000" framing, so it is the answer only if
  (1a) and (1b) both fail. If it is taken, say so explicitly rather than quietly shipping
  a panel button.

**Decision 2 — what actually renders the audio.**
- **(2a) Headless voice-engine render, extension-side.** The extension reads the instance's
  component state, reconstructs the engine from the shared pure core, renders the
  programmed note, and banks the result through the normal capture add-path. Exact and
  fully deterministic. **Trade-off:** the extension currently links `component_state_io`
  but deliberately **not** `sampler_core`/`pitch_shift` — `component_state_io` was split out
  precisely to avoid pulling the voice engine into the extension. This reverses that.
- **(2b) REAPER offline render of the hosting track**, with the programmed note. Reuses
  `OfflineRenderBackend` and with it the whole precision-invariant apparatus — exact
  bounds, bit-identical repeats, relative paths, tail control — for free. **Trade-offs:**
  it needs a *temporary* arrange mutation to program the note (the realtime backend's
  temp-track-created-and-removed-cleanly is the precedent), and the existing scope model
  has no "this one FX only" scope, so post-instrument track FX would be baked in unless a
  new bypass scope is added. The arrange must be byte-identical afterward.
- **(2c) The instrument renders, the extension banks it.** The instrument produces the
  audio (it already owns the engine) into a temp file or shared buffer; the extension
  moves it into the bank and indexes it. Splits the work along the existing ownership
  line — but adds a handoff artifact and its cleanup.

**Recommended sequence for the decision:** verify (1b) first — if it holds, the crossing
is nearly free. Then pick between (2a) and (2b) on the strength of the
"only-the-instrument, not the track chain" requirement: Daniel's ask says "send a trigger
or gate **through the sampler** offline," which favours (2a) or (2c) unless (2b) gains a
single-FX bypass scope. Record the verdict in this track's review, and if the verdict is
DEGRADED, escalate rather than improvise — the fallback is (1c) + (2a).

**Behavior — the chain.**
- **One gesture, whole chain.** A single click performs: offline pass → capture → bank
  update (replace or add-distinct) → instance re-point → parameter reset. **One action
  from the user's side, not a wizard.**
- **Offline pass through the instrument's own processing.** The audio is produced by
  sending a trigger or gate through the sampler **offline** — the instrument's own voice
  path, with filtering, pitching, and amp exactly as dialed. The recapture is of that
  processed output, not of the raw source.
- **The recapture is a bank capture like any other** — project-relative, indexed,
  browsable from any surface that browses the bank, recorded in the owned-file manifest,
  and governed by the same safety rules as every file the system creates.
- **The note is the capture's root.** The rendered note is the capture's root note — which
  is exactly why **the root-note parameter is not reset by resampling**: capturing at root
  is what makes root survivable, and resetting it would detune every subsequent iteration.
- **Gate's hold and tail come from the programmed window.** The programmed note length is
  the Gate hold bound — the gate holds for the note length, then releases; a Gate loop
  cycles within the held span and the render still terminates. The **end offset** is the
  home of the tail policy: captured time past the note's end is where the release rings.
- **Replace, or add distinct.** When nothing else references the source capture, the
  recapture **replaces** it as the bank entry; when other references exist, the original
  entry stays and the recapture is **added as a new distinct capture**. "Other reference"
  means **any usage of the source capture tied to it by the provenance/recapture system**
  — Ξ-W1-T1's records. Read plainly: the reference universe is the resample system's own
  lineage records, **not** the prune-protection universe. Bank multi-membership, items
  placed in the arrange, and a plain hold by another instance outside any recapture
  lineage do **not** force add-distinct, and need not for safety — the superseded file
  survives until prune, and prune's protection universe is unchanged and broader.
- **Replacement never destroys audio bytes.** "Replace" means the bank entry now denotes
  the recapture; the superseded file is not deleted. Prune remains the system's only
  file-deletion authority — resample writes a new file and retires the old one to
  reclaimable-by-prune status; it never overwrites or deletes it. Until a prune reclaims
  it, the pre-bake audio survives on disk — **the iterate loop's built-in recovery floor.**
- **The instance re-points** at the new/corrected bank capture and plays the baked sound.
- **Parameters reinitialize to default** — destructive to the dialed settings **by
  design**: the processing now lives in the recaptured audio, and neutral controls are the
  starting point for the next iteration.
- **Reset scope: only what the bake baked in.** Ratified by Daniel, not derived:
  - **Reset** (their effect is in the audio): the envelope contours — staged and spline
    alike — the filter parameters, master gain, the pitch envelope/engine settings, the
    velocity transfer curves (their effect at the programmed velocity is in the audio), and
    the loop points (they shaped the render, and old positions are meaningless against new
    audio).
  - **Survive** (mapping facts, not present in the audio): the **root note**, whatever
    remains of key mapping (key-tracking; any key-range concept Θ-W1-T1 settled), and the
    VOICE group (polyphony behavior leaves no trace in a single rendered note).
- **No timeline item, ever.** Resampling is a capture act: it writes a file to the bank and
  updates the index; nothing is placed in the arrange view. Any framing that auto-inserts
  the recapture is invalid — and if architecture (2b) is chosen, its temporary programming
  item must leave the arrange byte-identical.
- **Undo/recovery: a plus, not a requirement.** Welcome if it falls out cheaply; the
  feature ships without it. The guaranteed recovery path is the superseded file surviving
  on disk until a prune reclaims it.

**Acceptance criteria.**
- On a dialed-in instrument, one click yields all of: a recapture in the bank, the instance
  holding that recapture, and the baked-in audio parameters at their defaults — with the
  root note and the other surviving mapping parameters untouched.
- **The bake is audible and faithful:** after the click, playing the programmed capture
  note (root, at the programmed length, offsets, and velocity, in the active mode) through
  the now-neutral controls sounds as the dialed instrument sounded just before the click —
  the processing has moved from the controls into the audio.
- **A Gate-mode bake terminates on its own:** the gate holds for the programmed note
  length, then releases — even with loop-sustain active, the render ends. No indefinite
  capture.
- **After the bake the root note is unchanged** — iteration never detunes; the next bake
  plays the same root.
- **Sole-reference case:** the bank afterwards shows the recapture where the source
  capture's entry was; no other bank entry is disturbed. **Other-references case**
  (provenance-tied usage of the original exists, computed by Ξ-W1-T1): the original entry
  is untouched, a distinct new entry appears, and **every other holder of the original
  sounds exactly as before.**
- **The click deletes no file:** the superseded audio file still exists on disk afterwards,
  and only a later prune — under the settled orphan rules, only when nothing references it
  — can reclaim it.
- **The arrange timeline is untouched:** no item appears anywhere, on any track, and if a
  temporary programming item was used it is gone and the arrange is byte-identical.
- **Iteration composes:** dial → click → dial → click bakes the second pass onto the
  first's result, repeatable indefinitely.
- **Save/reload:** an instance holding a recapture reloads and plays it exactly like any
  other loaded capture.
- The bake adds nothing to `process()` — the offline pass runs off the audio thread.

**Open questions.**
- **The architecture decision [propose, with a verification step].** See above. The (1b)
  bridge verification is **[verify]**; the choice among the candidates is **[propose]**.
- **Extension presence [propose].** The instrument plays self-contained with the extension
  absent, but the bank is the extension's surface and resampling mutates the bank. The
  natural answer is that resample **requires the extension present and is cleanly
  unavailable — not silently lossy — without it**; propose the exact behavior at review.
- **Reset-scope edge cases [verify].** The rule is settled and the per-parameter
  classification is ratified. Only a genuinely new parameter — one arriving with a Θ track
  and absent from the ratified lists — is classified **against the rule** and surfaced at
  review. Not a new Daniel call. (Θ adds: curve exponents → reset; spline contours →
  reset, already named; the filter's velocity/key-tracking mod → reset with the filter;
  loop crossfade → reset with the loop points; the Staged/Spline mode flag → classify.)
- **Naming and lineage [propose, jointly with Ξ-W1-T1's lineage-record question].** When
  add-distinct fires, the new capture needs a display name (derived from the original?),
  and the bank some way to read iteration lineage across repeated bakes. One proposal,
  both tracks.
- **Provenance of the recapture — homed in item 17**, i.e. Ξ-W1-T1. A resample's recipe is
  the instrument's own settings, not a track's chain. Nothing to decide here beyond
  consuming that answer.

---

### Ξ-W3 — The capture-signal popup

**Depends on Ξ-W2 for:** the bake chain that the popup programs and its preview must not
diverge from. The acceptance criterion "preview and bake cannot diverge" requires one
render path, which W2 owns — building the preview against a second path is exactly the
defect the criterion exists to catch.

**One track.**

#### Ξ-W3-T1 — `capture-signal-popup`

**Goal.** Let the user program the capture signal — note length, offsets, velocity — and
hear it before committing the bake.

**Consolidates item 15 (the popup sub-feature).**

**Surface boundary — owns:** `core/instrument/ui/curve_popup`'s sibling — a new pure popup
geometry module for the capture-signal sheet (mirror the `curve_popup` precedent: centered
sheet, width/height clamps, title row, Close button rect, outside-sheet dismissal test) —
plus the editor's popup paint/input wiring in the deck or chrome band, and the preview
trigger's call into W2's render path. Reads Ξ-W1-T2's note-program record; does not
re-own it.

**Behavior.**
- **A popup menu programs the capture signal:** **note length**, **start and end offsets —
  in ms AND in beats** — and **velocity**.
- **A preview trigger button** auditions the capture note exactly as currently programmed
  — the user hears the bake before committing it — and the offline pass renders that same
  programmed performance.
- **Note length is a musical-division picker** spanning 1/64th to 64/1 with dotted and
  triplet multipliers.
- **Offsets are anchored** — start to note-on, end to note-off — and each is readable and
  editable in **both** ms and beats, the two views of one stored value.
- **Beat-denominated values resolve against the project tempo under the cursor.** The
  shell reads the tempo; the arithmetic is Ξ-W1-T2's.
- **The programmed velocity is the render velocity** — material because the velocity
  transfer curves modulate amp, pitch, and filter at that velocity.
- House-consistent: drawn through the shared kit by palette role, geometry pure and
  CTest-covered, no decorative animation.

**Acceptance criteria.**
- The popup exposes: note length as a musical-division picker spanning **1/64th to 64/1
  with dotted and triplet multipliers**; start and end offsets, **each readable and
  editable in both ms and beats**, anchored to note-on and note-off respectively; and
  velocity.
- **Its preview trigger auditions the capture note exactly as programmed, and the bake
  renders that same programmed performance — preview and bake cannot diverge.** Verify
  structurally (one render path), not just by ear.
- **Beat-denominated values resolve against the project tempo under the cursor:** the same
  programmed division yields a correspondingly different rendered duration when the tempo
  at the cursor differs.
- The programmed signal persists with the instance and round-trips save/reload.
- The popup's geometry and dismissal test are pure and unit-tested; no hit-test math lands
  in shell code.

**Open questions.** Both of Ξ-W1-T2's residuals (negative offsets; the note-length
denomination seam) surface here as UI consequences — if T2 answered them, this track
implements the answer; if T2 deferred either, this track is where it becomes visible and
must be closed.

---

## Phase Γ — The instrument's control surface

**Ships:** the deck reflowed into two categorical rows with a double-height MASTER bus deck,
a PITCH/RATE deck with playback-rate and baseline-pitch controls, a master limiter with
dynamic reported latency and a real output meter, one consistent knob interaction/taper law
across every variable control, a fix for staged contour traces drawing straight, and a
re-approached loop/crossfade marker UX under an explicit chrome-row loop enable.

**Consolidates:** none of the seventeen. Phase Γ came from a direct interview with Daniel
(2026-08-01); the product reasoning, the measured layout table, the invariant collisions and
the fork rulings are in **`docs/product/instrument-control-surface.md`**. Read §1.2 (the
layout table) and §7 (collisions) before dispatching any track here — every number in this
phase is derived there, and `docs/TODO.md`'s old deck-rework geometry is superseded.

**Fork state.** The phase's five original forks are **all ruled** (Daniel, 2026-08-01) —
indexed at spec §8.1, folded into the tracks below:
- **Γ-F1** — `kEditorMinHeight` stays **680**.
- **Γ-F2** — the limiter has **lookahead with DYNAMIC reported latency** (zero when off,
  the lookahead when on, reported to host PDC). *This inverted the product recommendation;*
  W1-T2's scope grows accordingly — spec §3.1.1.
- **Γ-F3** — the stage-time ceiling stays **2.0 s** in this phase. The 10 s ambition is
  carried in `docs/TODO.md` with its rationale and its prerequisites.
- **Γ-F4** — there **is** an explicit loop enable, and it lives on the **chrome row**, not
  in a deck. W2-T2's scope grows accordingly — spec §6.4.
- **Γ-F5** — MASTER's reserved slot is **one** cell. The 90 px headroom argument behind
  that is spec §1.6 and governs every future control addition.

**One fork remains open — Γ-F6, on W1-T2** (spec §8.2): the VST3 SDK defines
`restartComponent(kLatencyChanged)` as a host **deactivate/reactivate**, and this plugin's
`setActive` is destructive in both directions. Not blocking; gated on a DAW measurement W1-T2
performs first, with constant reported latency as the pre-agreed fallback.

**Sequencing against Phase Ξ — Γ runs BEFORE Ξ-W2.** Two reasons, both the same shape as
Ξ's own stated gate:
1. **The bake bakes the control surface.** Ξ-W2's settled reset scope enumerates parameters
   by name; Γ adds rate, pitch offset and the limiter flag. Shipping Ξ-W2 first means its
   reset list is incomplete on the day it lands. (Γ's doc §3.4 pre-classifies all three
   against the ratified rule — all **reset** — so this is a sequencing point, not a new
   Daniel question.)
2. **One params-payload ladder.** Γ takes v14 and v15. Ξ-W2 does not currently bump the
   payload, but Ξ-W3's programmed-signal persistence will, and two phases contending for the
   ladder is exactly the fight Θ's organizing constraint calls out.

**The organizing constraint.** Four surfaces are single-writer and dictate the wave shape:
`ui/deck_values.cpp` (the taper law, then the two new controls), `editor_paint_waveform.cpp`
(the contour trace, then the loop marks), the deck descriptors in `ui/deck_groups.cpp` +
`ui/knob_deck.cpp` (the new group, then the reflow), and the params-payload ladder. **Every
wave boundary below is one of those collisions**, not a preference. Where a wave has more
than one track, the tracks are disjoint by surface.

**Phase-wide acceptance criteria** (in addition to the ones stated at the top of this file):
- **Bypassed means byte-identical.** With the limiter off, the per-sample output path is
  byte-identical to today's bare ramped multiply — the same discipline that makes
  `live == nullptr` byte-identical to the pre-live core and the filter's exact skip at
  `modAmount == 0` hold the at-rest path unchanged.
- **No `ComponentState` sound change.** A project saved before this phase reopens sounding
  identical: absent rate lifts to 100 %, absent pitch offset to 0 st, absent limiter flag to
  bypassed. Re-tapering a knob (Γ-W1-T1) changes needle angles only — the payload stores raw
  engine doubles, so saved values reload bit-identical.
- **`kVelocityPitchRangeSemitones` / `kPitchDepthMaxSemis` (24.0) does not move.** It is
  load-bearing in the v12 wire format. The new Pitch knob **reads** it; it does not mint a
  second ±24 constant.
- **The window floor is 1190 × 680 and must not exceed 1280 × 720.** A track that pushes the
  floor past 1280 has failed, not overrun. **`kEditorMinHeight` stays 680** (Γ-F1). The
  remaining **90 px of width headroom is the budget for the life of this layout** — one deck
  cell is 60 px, so there is room for exactly one more, once. Spec §1.6 states the ledger;
  read it before adding any control. Chrome-row additions are a **separate purse** (they are
  paid for out of the title slot, not the floor) and must not be charged against this one.
- **Reported latency is zero unless the limiter is on.** `getLatencySamples()` returns 0 with
  the limiter bypassed, in every track and at every point in the phase. Only W1-T2 may
  introduce a non-zero value, and only under the limiter-on condition.
- **Geometry stays pure.** Every new layout, cap, label and hit-test rule lands in a pure
  CTest-covered module (`knob_deck`, `sample_bands`, `waveform_view`), never in a painter.

---

### Γ-W1 — Foundations

**Depends on:** nothing in this phase. All three tracks are disjoint by surface — T1 owns
editor input and the value/taper layer, T2 owns the engine and processor, T3 owns the
waveform painter's envelope trace. None touches the deck descriptors.

#### Γ-W1-T1 — `knob-interaction-law`

**Goal.** One consistent, unit-category-driven interaction and taper rule across every
variable control, landed **before** any new control is added so the new ones are authored
into it rather than retro-fitted.

**Spec:** `docs/product/instrument-control-surface.md` §4.

**Surface boundary — owns:** `core/instrument/ui/deck_values` (the taper maps, the
snap-unit table, `resetDeckParam`), `core/instrument/ui/param_slider` (the drag law),
`shell/instrument/editor_input_*` (modifier read + re-anchor), and the modifier-reading
helper the three input paths share. **Does not own** any deck descriptor, any parameter, or
the waveform painter.

**Behavior.**
- **Shift snaps to whole numbers in the control's displayed unit**; **Ctrl scales the drag by
  0.05**; **Shift+Ctrl = Shift wins** (Ctrl is ignored — with an integer-quantized output a
  finer drag yields the same sequence, so this is identity, not a compromise).
- **Snap unit by category:** ms knobs → whole ms; semitone knobs (incl. Rate, when it
  arrives) → whole semitones; percent/fraction knobs → whole percent; the 12 curve-exponent
  inner dials → whole numbers (which puts 1.0, the linear neutral, one snap away); master
  gain → whole dB; already-integer controls unchanged. Full table in the spec §4.2.
- **Mid-drag modifier transitions re-anchor** — on every press *and* release during an active
  drag, the current value becomes the anchor value and the current cursor position the anchor
  position. The value is continuous across the transition; only the rate changes. Without
  this the grab-anchored absolute drag (`kKnobDragRangePixels = 128`) jumps by
  `(1 − 0.05) ×` the accumulated delta.
- **Millisecond knobs become log-scaled.** Exactly 0 s at norm 0 and exactly
  `kEnvTimeMaxSeconds` at norm 1, monotone throughout; **10 ms lands within 0.12–0.20 of
  travel and 100 ms within 0.42–0.52**. The ceiling stays **2.0 s** — it reads
  `kGateStageMaxSeconds`, which the AHDSR overlay's schematic scale is derived from, and the
  two must agree.
- **Semitone knobs become log2/centre-expanded.** Symmetric, exactly 0 at centre, exactly
  ±`kPitchDepthMaxSemis` at the ends, monotone; **±7 st reached at 50–58 % of each
  half-travel**.
- **`resetDeckParam` bypasses the taper** — it writes the default value directly instead of
  round-tripping through `norm → value`. This *removes* the power-of-two dependency the
  header currently documents rather than working around it; that comment
  (`deck_values.h:42-46`) becomes wrong and must be rewritten.
- **Scope is the parameter, not the widget.** Deck knobs (outer ring and inner dial),
  envelope stage nodes and curve knots all honour it — they are surfaces onto one model, and
  a snap on one but not the others is a divergence. **Waveform markers are explicitly
  excluded**: they carry a shipped zero-crossing snap on the same modifier space and their
  domain is frames.

**Acceptance criteria.**
- Every taper change is verified **persistence-neutral**: a project saved before the change
  reopens with bit-identical stored values and identical audio; only needle angles move.
- Holding Shift mid-drag on each unit category lands the documented whole unit; releasing it
  does not jump the value.
- Holding and releasing Ctrl mid-drag is continuous — no step at either transition.
- Double-clicking any knob (outer ring and inner dial independently) lands **exactly** on its
  default at every taper, verified against a default-constructed `PlaySeconds` rather than a
  round trip.
- The log/log2 landmark positions above are asserted in `deck_values`' own tests.
- One shared modifier-read helper serves all drag surfaces; no second modifier grammar exists.

**Open questions.** None **[Daniel]** — fork Γ-F3 is ruled: **the ceiling stays 2.0 s.** The
10 s ambition Daniel described (*"a horrifically long decay with tight exp"*) is carried as a
`docs/TODO.md` entry, and **this track lands both of its prerequisites**: the log taper (which
is what makes a higher ceiling usable at the low end rather than unusable) and the reset
bypass (which retires the power-of-two dependency — 2.0 is a power of two, 10.0 is not).
**Neither is optional on that basis alone** — they are already required by this track — but
the engineer should know the reset bypass is doing double duty, and should not "simplify" it
back into a norm round-trip.

#### Γ-W1-T2 — `master-bus-audio`

**Goal.** The master limiter and the meter's **audio and publication halves**, plus **the
plugin's first latency reporting** — no editor drawing. Landing the audio ahead of the deck is
what lets Γ-W3 draw against real published state instead of a stub.

**Spec:** `docs/product/instrument-control-surface.md` §3.1, **§3.1.1 (latency — read this
first)**, §3.2–3.3, §3.5, §7.10, §8.2.

**Surface boundary — owns:** a new pure limiter module and a new pure meter-ballistics
module under `core/instrument/engine/` (each with its own `<module>_tests` target),
`shell/instrument/reasampler_processor` (the chain, the published block state, **and the
`getLatencySamples` / `restartComponent(kLatencyChanged)` path**), and **params payload v14**
(the limiter enable flag). **Does not own** MASTER's deck geometry or any drawing — that is
Γ-W3-T1.

**Behavior.**
- **Chain:** `voice mixer → master gain (existing ramped multiply) → limiter (bypassable) →
  output bus`, with the meter tapped at the **bus output, post-limiter**.
- **Limiter: a single toggle, no configurable controls.** Baked ceiling **−0.3 dBTP**.
  Default **off**. **No makeup gain, ever, of any kind** — transparent at rest.
  Stereo-linked detection (max |L|,|R| drives one gain) so the image is not moved.
- **True-peak detection is sidechain-only** — an oversampled detector in the sidechain, never
  oversampling the signal path. Factor is the engineer's call under the measure gate.
- **Lookahead, with DYNAMIC reported latency (Γ-F2, ruled).** `getLatencySamples()` returns
  **0** when the limiter is off and **the lookahead in samples** when it is on; the toggle
  calls `IComponentHandler::restartComponent(kLatencyChanged)`. **None of this exists today** —
  there is no `getLatencySamples` override, no `kLatencyChanged`, and no `restartComponent`
  call site anywhere in `src/`; the plugin ships the SDK default of 0. This track introduces
  the plugin's first latency reporting.
- **The restart is the risky part and it is fenced.** The SDK defines `kLatencyChanged` as a
  host **deactivate/reactivate** (`pluginterfaces/vst/ivsteditcontroller.h:105-108`), and this
  plugin's `setActive` is destructive in both directions (`reasampler_processor.cpp:85-109`) —
  deactivate frees every sounding voice, reactivate re-decodes the WAV. Four requirements, all
  acceptance criteria:
  1. **Verify the whole call sequence against the vendored Steinberg SDK** before writing it,
     including the ordering rule that the new latency is what `getLatencySamples` returns
     *after* `setActive(true)` — so **the reported value must derive from persisted state, not
     from a transient the deactivate clears.**
  2. **Prove the restart does not disturb the output bus arrangement.** The output stays one
     permanently-stereo bus, never renegotiated.
  3. **Ship a regression test in the spirit of `testDualMonoStereoSampleRendersCentered`** —
     a dual-mono capture rendered across a limiter toggle stays centered, L ≡ R.
  4. **`restartComponent` is never called from `process()`.** Main/UI thread only, and
     coalesced so repeated clicks produce one restart per settled state.
  **This is NOT the change `reasampler_processor.cpp:66-68` forbids.** That warning is against
  reintroducing per-mode **bus** renegotiation (`kIoChanged` class), which panned a dual-mono
  capture hard right in the host's pin re-routing; `kLatencyChanged` is a different flag and the
  bus is untouched. But the precedent — mid-session `restartComponent` in this plugin has
  already shipped one real regression — is exactly why (2) and (3) are non-negotiable.
- **Flipping the toggle during playback: apply immediately, do NOT defer to a transport
  boundary** (product ruling, spec §3.1.1). A deferred restart leaves the plugin misaligned by
  the lookahead with no visible cue, which is worse than a visible interruption; and the host,
  not the plugin, schedules the deactivate/reactivate anyway. Two mitigations are in scope:
  the engage/disengage is covered by a short (≤ 10 ms) equal-gain crossfade so **the plugin
  emits no discontinuity of its own**, and the limiter enable is classified **not automatable**
  (`docs/product/parameter-automation.md` §3.8) so nothing can flip it at rate. It is also
  **not** the plugin's `kIsBypass` parameter.
- **Per block the processor publishes, as relaxed atomics:** per-channel peak `max|x|`, a
  latched clip flag, and the block's maximum gain reduction. **No dB conversion, no
  ballistics, no hold timers on the audio thread** — the UI converts and runs ballistics from
  block peaks and elapsed time. This widens the existing advisory-peak pattern
  (`reasampler_processor.h:109-113`), which is not reusable as-is.
- **Meter ballistics (pure, unit-tested):** instantaneous rise; **fall 20 dB/s**; peak-hold
  latched at the running max, **held 1.5 s**, then falling at the same rate; scale **linear in
  dB over −60…+6 dBFS**; clip latches at block peak ≥ 0 dBFS and is cleared on request.
- **`ComponentState` payload v14** appends the limiter flag as a strict suffix on the existing
  discipline; a v13 blob is a strict prefix and lifts to bypassed.

**Acceptance criteria.**
- **With the limiter bypassed the rendered output is byte-identical to the pre-change build**,
  asserted by a regression baseline, not by ear.
- With the limiter engaged, no output sample exceeds the ceiling on program material that
  exceeds it by up to +12 dB; with it bypassed and gain driven, the output does exceed
  0 dBFS (proving the toggle is doing the work).
- **Nothing is louder at rest with the limiter on.** A signal that never reaches the threshold
  is bit-identical engaged and bypassed.
- No allocation, no lock, no transcendental on the per-sample path; the measure-and-report
  gate reports per-voice-block CPU with the limiter engaged at 32 voices.
- The meter-ballistics module is pure and CTest-covered: rise, 20 dB/s fall, 1.5 s hold, clip
  latch/clear, and the dB↔pixel map are all asserted without a host.
- A project saved before this change reopens with the limiter bypassed and sounding identical.
- **`getLatencySamples()` returns exactly 0 with the limiter off**, and the lookahead in
  samples with it on — asserted against the persisted flag, and correct across a
  deactivate/reactivate cycle.
- **A dual-mono capture rendered across a limiter toggle stays centered** (L ≡ R), and the
  output bus arrangement after a latency-change restart is identical to before it.
- **The plugin emits no hard step at the toggle** — the engage/disengage crossfade is asserted
  on a rendered signal, not judged by ear.

**Open questions.**
- **[Daniel] fork Γ-F6 — is the deactivate/reactivate cost acceptable?** (spec §8.2.) **Not
  blocking, and this is the track's FIRST deliverable:** a verification spike in REAPER —
  flip the limiter with notes held, during playback and while stopped, and **record what
  actually happens** (do notes cut? is the re-decode perceptible? does transport hiccup?).
  The SDK mandates the deactivate/reactivate; what REAPER does with it is DAW-verifiable only.
  Ship the ruled dynamic-latency design regardless; if the observed behaviour is as ugly as
  the SDK's worst case allows, the **pre-agreed fallback is constant reported latency** (the
  delay line engaged whether or not the limiter is on), which needs one word from Daniel and
  **no DSP change** — only the latency-reporting predicate moves. Report the measurement to
  Daniel with a recommendation; do not choose the fallback unilaterally.
- **[verify]** `temp_cortex/` has already been assessed and **rejected** (spec §3.5) — do not
  re-litigate it, and do not transplant from it.
- **[verify]** whether `setActive(true)`'s `reloadInstrument()` can reuse the already-decoded
  `SampleData` on a latency-restart reactivate rather than re-reading the bridge and
  re-decoding the WAV. If it cannot cheaply, that is an **accepted cost to be recorded**, not
  a reason to restructure `setActive` — its destructive shape is deliberate and its reasoning
  (ghost sustained voices on reactivate) is documented at the call site.

#### Γ-W1-T3 — `contour-trace-curves`

**Goal.** Staged envelope segments draw as the curve their exponent defines, so the
mid-segment knot stops floating off its own trace.

**Spec:** `docs/product/instrument-control-surface.md` §5.

**Surface boundary — owns:** `shell/instrument/editor_paint_waveform.cpp`'s staged-envelope
trace and any pure tessellation helper it needs. **Does not own** the loop/crossfade marks
(Γ-W2-T2), `envelope_overlay`'s vertex model, or the drawn-EG (spline) trace.

**Behavior.** The defect is verified: `editor_paint_waveform.cpp:218` drops knots
(`if (v.knot) continue;`) and joins the remaining vertices with straight strokes, and
`curveMap` is never called in the paint path even though the exponent is in scope at `:211`.
Knot *positioning* already honours the exponent via `curveMidLevel`
(`envelope_overlay.cpp:94-105`) — that divergence is the visible symptom. The fix draws each
sloped stage through **the same `curveMap` the audio uses**, so trace and sound cannot
diverge; tessellation approach is the engineer's call.

**Acceptance criteria.**
- **At every exponent the knot's centre lies on the trace, within 1 px** — the reported defect,
  stated as the gate.
- **At exponent 1.0 the segment is visually identical to today's straight line.**
- No visible faceting at the widest segment the canvas can produce; a fixed low tessellation
  count is not acceptable at full width.
- All three envelopes, both play modes, all sloped stages (attack/decay/release) — one paint
  path, one fix.
- The established trace grammar is unchanged: one weight, `kEnvTracePx = 2.0`, through the
  analytic stroker. Both overlay layout policies (AHDSR right-anchored schematic, AHD 1:1)
  are honoured unchanged. The spline overlay's own trace is untouched.
- **Audio is unchanged** — this is a drawing defect only; a regression baseline proves it.

---

### Γ-W2 — New controls, and the overlay's marks

**Depends on Γ-W1 for:** T1 depends on W1-T1 — Rate and Pitch must be authored into the
finished taper/modifier law, not retro-fitted into it (and the semitone taper must exist
before a second semitone knob does). T2 depends on W1-T3 — both write
`editor_paint_waveform.cpp`, and running them together is a merge fight in one file.

**Disjointness — restated after the Γ-F4 ruling, because it changed.** T1 owns the parameter
model, the engine and the deck descriptors; T2 owns the waveform band's marks and their pure
geometry **and now also the chrome row's loop enable**. The two are disjoint at the module
level with **one named exception: `shell/instrument/editor_session.cpp`.** T1 may touch it for
the third commit tier's routing; **T2 owns `pickedMarkers` and `applyMarkers` there and nothing
else.** The partition is by function and the two do not overlap — this is a textual merge
adjacency, not a semantic contention — but it is a shared file in a phase whose wave boundaries
are otherwise single-writer surfaces, so it is stated rather than discovered at merge. Whichever
track lands second rebases onto the first.

**The format ladder stays clean.** The loop enable maps onto the existing
`SampleLoop::hasLoop`, which is already persisted and whose `start`/`end` are already written
unconditionally — **no new field, no version bump** — so T1 keeps sole ownership of payload v15
exactly as specced.

#### Γ-W2-T1 — `pitch-rate-deck`

**Goal.** PITCH becomes **PITCH/RATE**: three knobs (`Key Trk | Rate | Pitch`) under the
existing Varisp|Presrv toggle, with both new controls wired through the engine.

**Spec:** `docs/product/instrument-control-surface.md` §2.

**Surface boundary — owns:** `core/instrument/engine/play_params.h` +
`core/instrument/map/play_seconds.h` (the two new fields),
`core/instrument/map/component_state_io` + `params_payload` (**payload v15**),
`core/instrument/engine/voice.{h,cpp}` (the compounding and the note-on latch),
`core/instrument/ui/deck_groups` (the PITCH/RATE descriptor **and** the three-state live
predicate), `core/instrument/ui/deck_values` (the two new bindings). **Does not own** the
deck's row layout — that is Γ-W3-T1 — nor the real time-stretcher (Γ-W4-T1).

**Behavior.**
- **Rate: 50 %–200 %, default 100 % at true knob centre, exponential taper** — 50 % = −12 st,
  200 % = +12 st, musically symmetric. This is **linear in semitones over ±12** and is the
  stated exception to W1-T1's centre-expansion law (which applies to semitone knobs whose
  throw exceeds ±12).
- **Pitch: a baseline pitch offset, ±24 semitones**, centred, on W1-T1's centre-expanded
  semitone taper. **Reads `kPitchDepthMaxSemis`; does not mint a second constant.**
- **Varispeed:** keytrack ratio × rate ratio × pitch-offset ratio **compound into a single
  read-increment multiply**; the rate offset applies to the varispeed pitch. Composes with
  the pitch envelope's existing per-frame `ratio_` multiply — **no new per-sample stage**.
- **Preserve:** rate is an **absolute** value driving **duration only**; keytrack and pitch
  offset drive the pitch shifter. **Interim implementation:** a resampled read with the
  resulting pitch change cancelled in the existing SOLA shifter. This is an explicit duration
  control, **not** a covert Preserve path — `core/instrument/CLAUDE.md`'s "never wire
  `WDL_Resampler` as the duration-preserving path" is untouched. Quality is Γ-W4-T1's.
- **Rate is latched at note-on**, delivered by a **third commit class**: published into the
  live block like any live parameter, read only by `snapLive`, never by `applyLive`.
  `isLiveDeckParam`/`liveCommitFor` widens from two states to three
  (`Live` / `NoteOnLatched` / `Reload`) in that one predicate — **not** a second table, and
  **not** the reload tier (a swept knob must never trigger a WAV re-decode). **Record the
  reason in the header:** loop resolution and contour mapping are note-on folds, so live rate
  means re-folding a resolved loop and re-mapping a contour mid-note.
- **Pitch is live** — under Varispeed one more factor in a multiply the pitch envelope already
  performs; under Preserve an addend to a shift the pitch envelope already modulates.
- **Loop points scale with rate; contours scale with rate.** Neither rewrites stored values:
  the loop is source-frame facts traversed at the new increment (Varispeed) or the new read
  rate (Preserve), and a contour is a function of normalized position. **Staged envelope stage
  times do NOT scale** — 30 ms is 30 ms at any rate. That asymmetry is deliberate: a contour is
  of the sample, a staged envelope is of the performance.
- **Deck descriptor:** three cells; `captionWidth` **70**, hard ceiling **80** (above that the
  caption row overtakes the 180 px knob row and the group exceeds 192). If the text will not
  fit at 80, narrow the `Varisp|Presrv` segments 48 → 44 (ceiling becomes 88) — **do not widen
  the group**.
- **Payload v15** appends both fields as a strict suffix; a v14 blob lifts to rate 100 % /
  pitch 0 st, bit-identical playback.

**Acceptance criteria.**
- Rate at 50 % plays an octave down and half speed under Varispeed; at 200 %, an octave up and
  double speed. Under Preserve the same settings change duration only — pitch is unchanged
  within the shifter's tolerance.
- Rate at exactly 100 % and Pitch at exactly 0 st render **bit-identical** to the
  pre-change build, in both engines.
- Shift-drag on Rate lands on whole semitones (so an octave and a fifth are reachable by
  hand); Shift-drag on Pitch lands on whole semitones; Ctrl gives cents on both.
- **A Rate change while a note sounds does not alter that note**; the next note-on takes it.
  **It does not trigger a reload or an engine rebuild** — assert the tier, not just the sound.
- A Pitch change **does** move a sounding note, in both engines.
- With a loop set, changing Rate changes the loop's audible period without moving either
  waveform marker.
- The PITCH/RATE group measures **exactly 192 px**; adding the two `DeckParam`s produces a
  compile error in `isLiveDeckParam`'s exhaustive switch until they are classified.
- A v14 project reopens at rate 100 % / pitch 0 st and sounds identical.

**Open questions.** None **[Daniel]**. **[propose at review]** the exact interim
resample+cancel composition and its clamp behaviour at the range extremes, which Γ-W4-T1 then
replaces.

#### Γ-W2-T2 — `loop-crossfade-ux`

**Goal.** Give the loop an explicit enable, make the loop and crossfade marks legible, and
paint the crossfade where it is actually heard.

**Spec:** `docs/product/instrument-control-surface.md` §6 — **read §6.1 (the diagnosis),
§6.4 (the enable) and §6.5 (trade-offs) in full before starting.** This is the phase's one
genuinely designed surface; the sections are the brief.

**Surface boundary — owns:** `shell/instrument/editor_paint_waveform.cpp`'s marker/loop draw,
`shell/instrument/editor_input_waveform.cpp`'s marker hit-test routing,
`core/instrument/ui/waveform_view` (cap rects, label boxes, the label-suppression rule — all
pure, all CTest-covered), and — **new, from the Γ-F4 ruling** —
`core/instrument/ui/sample_chrome` (the enable's rect in the toolbar control run),
`shell/instrument/editor_paint_chrome` + `editor_input_chrome` (its draw and hit-test), and
`shell/instrument/editor_session.cpp`'s **`pickedMarkers` / `applyMarkers` only** (the
retention rule — see the wave header for the shared-file partition). **Does not own**
`loop_span`, the crossfade model, any parameter, or any `ComponentState` version. **This
track changes drawing, hit-testing and one editor-state retention rule — no format change.**

**Behavior.**
- **An explicit loop enable on the CHROME ROW (Γ-F4, ruled).** A two-segment `Loop Off|On`
  toggle joins the toolbar row's right-anchored control run, **immediately left of the
  `Mono|Stereo` toggle**, with Browse still rightmost. Loop is a waveform-overlay concept and
  **has no deck** — a deck cell was never the right home. Because the run is right-anchored
  and the title slot absorbs it, **this costs zero window width and none of the 90 px
  headroom**; if the title will not hold its text at the 1190 floor, **the enable's segments
  narrow — the floor does not move.**
- **The enable IS `SampleLoop::hasLoop`. No new field, no version bump.** The field already
  exists (`play_params.h:210`), is already what `resolveLoop` refuses on
  (`loop_span.cpp:12`), and is already persisted in the payload's `loopOverride` block —
  where **`start`/`end` are written unconditionally whatever `hasLoop` says**
  (`params_payload.cpp:31-36`), so the wire can already carry "off, with a span remembered."
  What changes is the field's *provenance*: today it is derived from the marker gesture, and
  after this track it is **user-owned**, with the gestures as shortcuts onto it.
- **Collapse-to-off survives as a shortcut, not as a second state machine.** `hasLoop` is the
  single authority; four gestures reach it:
  | Gesture | Enable | Span | Crossfade |
  |---|---|---|---|
  | Enable → On | on | retained | retained |
  | Enable → Off | off | **retained** | **retained** |
  | Collapse the span onto itself | off | **destroyed**, re-parked at `defaultLoopBounds` | **zeroed** |
  | Drag either loop mark while off | **on** | takes the drag | retained, re-clamped |
- **Two consequent behaviour changes, each with its reason.** (a) `pickedMarkers`'
  re-park (`editor_session.cpp:221-226`) currently triggers on `!hasLoop`; it must become
  conditional on the span being **invalid** (collapsed / inverted / out of range) rather than
  on the enable being off — a toggle whose off→on does not restore what was there is a delete
  button, not a toggle. (b) `applyMarkers`' crossfade zeroing (`:240-243`) moves from "the
  enable is off" to "the span was destroyed." **The original reasoning is preserved, not
  overruled:** it zeroes so a stale length cannot silently re-apply against a span that no
  longer exists; with the span retained, its clamp bound is retained too and there is nothing
  stale.
- **The "drag me" affordance splits into two off-states.** Off with **no span ever set** —
  pair parked at `defaultLoopBounds`, Disabled, caption `DRAG TO SET LOOP`. Off with a **span
  retained** — pair Disabled *at its own positions*, caption `LOOP OFF` (there is nothing to
  "set"). In both, **dragging a mark turns the enable on** — the shipped drag-to-create
  gesture survives and now teaches the enable by demonstration.
- **In Trigger the enable draws Disabled and inert, and does NOT clear `hasLoop`** —
  Disabled-not-hidden, the same grammar as the marks, with its state restored on the return to
  Gate. This transitively covers the drawn-EG case via `enforceGateUnavailableWhileDrawn`
  (`play_params.h:198-205`), which forces Trigger whenever an envelope is drawn — one
  predicate, not a second rule. **Disabled-but-grabbable (the off marks) vs.
  Disabled-and-inert (Trigger) is deliberate:** the user's own off is reversible by the very
  gesture on offer; Trigger's refusal comes from the engine and no drag can talk it out of it.
- **One mark grammar: line + shaped cap + label. The cap IS the grip.** Four marks:
  **START** (`accent/primary`, solid right-pointing triangle cap, solid line — the only
  primary-ink mark, because it is the only one always in effect); **LOOP** (`accent/secondary`,
  L-cap opening right); **END** (`accent/secondary`, L-cap opening left); **XFADE**
  (`accent/secondary` reduced alpha, ramp cap, **dashed** line — a soft boundary). This
  replaces the bare 10 px orphan tab that today marks the crossfade with no line of its own.
- **Labels** in `Font::Micro`/`TextDim`, drawn **beneath** the trace and handles in z-order.
  A mark's label **re-draws on top on hover or drag** of that mark. **A label is suppressed if
  its box would overlap one already placed**; placement order is grabbed/hovered first, then
  START, LOOP, END, XFADE. Occlusion by an envelope node is **accepted and named** — the cap
  shape carries the identity permanently, the label is for learning.
- **The crossfade moves to `[loopEnd − crossfade, loopEnd)`** — where it is audible. The
  handle moves to the loop-end side; **drag direction is unchanged** (left lengthens), so the
  muscle memory survives.
- **The crossfade region draws as a top-and-bottom edge wedge, NEVER as a second fill.** A
  triangular band at the overlay's top and bottom edges growing from zero at
  `loopEnd − crossfade` to ~10 px at `loopEnd`. **This is a hard constraint:** the region is
  now *inside* the loop span, where a translucent fill would stack on the 0.20 loop fill, and
  the envelope trace crossing that fill is a known, accepted under-floor pair at 2.25:1
  (`editor_paint_waveform.cpp:28-34`), whose own note says the FILL is what changes if it is
  ever resolved. **The loop fill's peak alpha must stay exactly 0.20.**
- **The ingredient draws as a ghost.** `[loopStart − crossfade, loopStart)` draws the mirror
  wedge at half alpha, no handle — **a hairline dashed outline at rest, filling in on hover or
  drag of the crossfade handle**. This makes the `crossfade ≤ min(start, loopLength)` clamp
  self-explanatory: the fade stops growing exactly when the ghost's left edge reaches START or
  LOOP, so the user sees the reason instead of hitting an invisible wall.
- **Trigger mode:** the loop pair and the crossfade mark draw **Disabled and are not
  grabbable**, with a dim `LOOP — GATE ONLY` caption — Disabled rather than hidden, matching
  the editor's existing Gate-segment grammar, and because hiding a set loop on a mode flip
  destroys information the user put there. START stays fully live.

**Acceptance criteria.**
- The four marks are distinguishable by ink and cap shape with the labels suppressed, and
  named when they are not.
- **The shaded crossfade region sits over the frames where the fade is audible** — verify
  against a rendered loop, not by reading the code.
- Every mark is grabbable by its cap; grabbing a mark shows its label.
- The crossfade at its clamp shows the ghost's left edge coincident with the bounding mark.
- **The loop fill's peak alpha is unchanged at 0.20** and the accepted 2.25:1 trace pair is
  neither improved nor worsened.
- In Trigger, no loop mark accepts a grab, the chrome enable is Disabled and inert, and the
  reason is on screen. Returning to Gate restores the enable's prior state.
- **Turning the enable off and on again restores the loop exactly** — same span, same
  crossfade, no re-park. Collapsing the span instead turns it off, re-parks at
  `defaultLoopBounds` and zeroes the crossfade. Both paths asserted.
- **Dragging a loop mark while the enable is off turns it on**, in both off-states.
- **The enable costs no window width:** `kEditorMinWidth` is unchanged by this track, asserted
  by the same derived test that guards the floor.
- **No `ComponentState` version moves; no new persisted field; `resolveLoop` is untouched;
  audio is unchanged.** The enable round-trips save/reload through the existing
  `loopOverride` block, in both states, with the span retained across an off.
- All cap/label/suppression geometry is pure and unit-tested; no hit-test math in the painter.
  The enable's rect lands in `sample_chrome` alongside the rest of the control run.

**Open questions.**
- **[propose at review, then verify by hand]** The claim-arbitration inputs change:
  `markerHandleRect` today gives a tab to the crossfade only, and `resolveWaveformClaim`
  breaks ties by smallest nominal target area. Giving every mark a cap-grip changes the
  candidate set **and every nominal area in it**. The arbitration must be re-derived, and
  `docs/TODO.md`'s open entry *"Pre-existing staged-envelope-node shadow at zero-attack"*
  must be **re-evaluated against the new cap geometry and its outcome recorded** — resolved or
  worsened, either is acceptable, silence is not.
- **No [Daniel] questions.** Fork Γ-F4 is ruled — there **is** an explicit enable and it is on
  the chrome row, in this track. The prior framing ("an enable needs a cell, so it is a Γ-W3
  layout decision") was wrong and is retired: loop has no deck, so it never needed one.
- **[propose at review]** every site that currently *infers* `hasLoop` — two in
  `editor_input_waveform` (`:255`, `:258`), two in `editor_session` (`:222`, `:236`) — is now
  writing to a user-visible control rather than to an internal flag. Re-read each in that
  light; "it still compiles" is not a disposition.
- **Named escalation, not a fallback to take silently:** if the top strip reads crowded in the
  DAW, the pre-designed answer is the marker rail (spec §6.2, Direction 2) — a larger build
  that would also dissolve the arbitration problem structurally. Escalate; do not improvise a
  half-rail.

---

### Γ-W3 — The reflow

**Depends on Γ-W2 for:** the PITCH/RATE descriptor (W2-T1) — the reflow measures the real
three-cell group, and laying it out against a forecast of that group means re-measuring
afterward. **Depends on Γ-W1 for:** W1-T2's published meter/GR/clip state, which MASTER's
deck draws; drawing against a stub would mean building the meter twice.

**One track.** The row law, the group inventory, the double-height deck and the window floor
are one geometry decision spread over `knob_deck`, `deck_groups`, `sample_bands` and the deck
painter. Splitting it would put two tracks in the same three pure modules.

#### Γ-W3-T1 — `deck-reflow`

**Goal.** Two categorical rows plus a double-height MASTER bus deck, inside a 1280 × 720
ceiling, returning 112 px to the waveform.

**Spec:** `docs/product/instrument-control-surface.md` §1 (the whole section, incl. the §1.2
measured table **and §1.6, the headroom ledger**) and §3.2–3.3 (what MASTER draws). **§7 lists
the invariants this track invalidates or widens — read it before touching `knob_deck.h`.**

**Surface boundary — owns:** `core/instrument/ui/knob_deck` (the row law, the double-height
group, the justification), `core/instrument/ui/deck_groups` (row assignment, FILTER's toggle
move, MASTER's inventory), `core/instrument/ui/sample_bands` (`kEditorMinWidth`), and
`shell/instrument/editor_paint_deck` (the MASTER meter/limiter/bubble draw). **Does not own**
any parameter, the limiter DSP, or the waveform band.

**Behavior.**
- **Row 1 (sound), one row, non-negotiable:** PITCH/RATE 192 · FILTER 432 · VELOCITY 192 ·
  VOICE 164 = **980** natural.
- **Row 2 (contour):** PITCH ENV 252 · FILTER ENV 312 · AMP ENVELOPE 312 = **876** natural.
- **MASTER is double-height (216 px) and right-anchored**, outside both rows, 142 px wide.
- **FILTER's `Band|Notch` moves from its row-toggle position to the caption corner**, taking
  the group 524 → **432** (−92 px). It occupies FILTER's currently-unused `captionToggle2`
  slot — **no new geometry is required**.
- **VOICE keeps its `Retrig|Legato` row toggle.** Moving it to the caption makes VOICE
  *wider* (226, not narrower), because its caption row is the binding side. Verified; do not
  "fix" it.
- **Justification law, applied to BOTH rows:** space-between within the row block; slack
  divided equally among the row's (n−1) gutters, integer residue to the leftmost;
  **no gutter narrower than `kDeckGroupGap` (12)**. **Decks are never stretched.** MASTER is
  not part of either row's justification.
- **Row block = 1020 px at the floor**, giving row 1 gutters 12/14/14 and row 2 gutters 72/72,
  at which width **FILTER's right edge and FILTER ENV's right edge both land on x = 636**.
  That tie-line, row 2's equal gutters, and row 1's minimum gutter being exactly
  `kDeckGroupGap` all hold at 1020 and only at 1020 — **this is why the floor is 1190 and not
  1186.** Above the floor the tie-line drifts and that is accepted (spec §1.3).
- **`kEditorMinWidth` 980 → 1190**; `kEditorMinHeight` **stays 680** (Γ-F1, ruled — the
  reflow's 112 px goes entirely to the waveform); deck band height 328 → **216**; waveform
  band at the floor 246 → **358**.
- **The 90 px of remaining headroom is the budget for the life of this layout**, and one deck
  cell is 60 px. **This is why MASTER's reserved slot is ONE cell** (Γ-F5, ruled): two would
  spend 60 of the 90 up front on a control nobody has named, leaving 30 — which would freeze
  row 1 forever, since any later row-1 addition needs 60. Widening MASTER later costs the same
  60 it would cost now, and by then the trade is against a real control instead of a guess.
  **State this ledger where a future reader will hit it** — spec §1.6 is its home, and a
  reader proposing a new knob needs to see it before they propose.
- **MASTER's interior** (spec §1.4, exact to the pixel): caption row with the limiter toggle
  and a **round** 12 px `warn` GR bubble in the far corner (non-interactive — the same slot the
  envelope decks' radio uses; round so it reads as a lamp, not a control); **gain knob in the
  upper-left cell at box-relative y = 26** and a **reserved empty slot at y = 138** — i.e. the
  two cells land on row 1's and row 2's knob baselines exactly, which is what stitches the
  spanning deck to both rows; **meter column 62 px wide × 186 px tall** on the right.
- **Three rules not to generalise wrongly:** MASTER's left column uses **fixed cell slots at
  the two baselines, NOT the horizontal run-division law** (that law would stretch one knob
  over 186 px); the reserved slot **draws nothing** (blank reads as breathing room, a dashed
  placeholder reads as unfinished); the meter is **one rect spanning both baselines**, not two
  per-row meters.
- **The meter draws W1-T2's published state**, with the ballistics run on the UI timer.
  **Bar count follows the same `LaneSplit` decision `waveformSurface` already folds** (channel
  mode ∧ source channel count) — one wide bar when the waveform draws one lane, two skinnier
  bars when it draws two. Not a second rule: a mono source in stereo mode is dual-mono, and
  two identical bars would be a lie.
- **Meter appearance:** bar in `accent/primary`; peak-hold tick 2 px in `text/primary`; clip
  cap in `warn`, latched, click-to-clear; scale linear in dB over −60…+6 with ticks every
  6 dB and numerals at 0/−12/−24/−36/−48/−60, the 0 dB tick heavier. **No green/yellow/red
  segmentation** — `warn` stays reserved for clip states.

**Acceptance criteria.**
- At the floor width the deck lays out in **exactly two rows plus the spanning MASTER**,
  **by construction** — asserted against the group inventory, not observed as a wrap outcome.
- Every group's width matches the §1.2 table exactly, **in both Gate and Trigger** (row 2's
  natural width is mode-stable at 876 because the reserve slots hold FILTER ENV and AMP at
  312 in both modes — assert it).
- Row 1 and row 2 are **flush left and flush right**; at the floor width the filter tie-line
  is exact (both edges at x = 636) and row 2's two gutters are equal.
- **`kEditorMinWidth` is 1190 and the floor is ≤ 1280 × 720**, asserted by a derived test
  rather than a literal (the Θ-W6-T1 precedent).
- The waveform band is **358 px at the floor**, and the deck band is 216.
- MASTER's gain knob shares a knob baseline with FILTER's knobs; its reserved slot shares one
  with AMP ENVELOPE's.
- The meter reads correctly in mono and stereo, the peak-hold tick holds 1.5 s, the clip cap
  latches and clears, and the GR bubble lights only while the limiter reduces gain.
- **With the limiter engaged the clip cap never latches** on material the limiter is catching;
  if it does, that is a defect report against W1-T2, not a user error.
- `knob_deck`'s and `sample_bands`' tests are updated to the new law, and the invalidated
  notes in `knob_deck.h` (the fourteen-pixel headroom figure; the cells-and-floor pairing) are
  **re-derived, not deleted** — spec §7.1, §7.4.

**Open questions.**
- **[propose at review]** Whether the greedy whole-group wrap survives at all as a sub-floor
  degrade, or is replaced outright by explicit row assignment. What is **not** optional: at
  and above the floor width the layout is the specified arrangement, reached by construction.
  `DeckLayout::rowCount`/`::height` change meaning either way (spec §7.3).
- **No [Daniel] questions.** Forks Γ-F5 (**one cell**) and Γ-F1 (**680 stays**) are both
  ruled; they are stated in Behavior above, not carried here as options.
- **[verify]** `deck_groups.cpp`'s `kEnvModeSegW = 23` ceiling rises to **47** once PITCH ENV
  is on row 2 (AMP binds at 55). No change is required; the comment stating the old ceiling
  stops being true and must be corrected (spec §7.2).

---

### Γ-W4 — The Preserve time-stretcher

**Depends on Γ-W2 for:** Rate existing as a shipped, working control on the interim
resample+cancel path. Landing the stretcher against a working feature makes it a measurable
quality upgrade with an A/B; landing them together would make one track responsible for both
a feature and an algorithm.

**One track.** **This is the phase's largest unknown** — flagged the way Ξ-W2-T1's crossing
was. If the measure-and-report gate fails, what gives is the *algorithm choice*, not Rate:
the interim path already ships in W2-T1, so the fallback is "keep the interim path and record
why," not "cut the feature."

#### Γ-W4-T1 — `preserve-time-stretch`

**Goal.** Replace the interim resample+cancel composition with a real pitch-preserving
time-stretcher written from established state-of-the-art literature.

**Spec:** `docs/product/instrument-control-surface.md` §2.5.

**Surface boundary — owns:** `core/instrument/engine/pitch_shift` and whatever new pure
module the stretcher needs, plus `voice.cpp`'s Preserve read path. **Does not own** any
parameter, any UI, or the varispeed path.

**Behavior and constraints.** The algorithm is **the engineer's call under a
measure-and-report gate — this plan deliberately names none.** The constraints:
- **CPU stance (Daniel, verbatim intent):** *"we should be efficient but accept the cost of
  high-quality algorithm choices. It's 2026, most people's computers can handle audio with
  ease. Just don't be wasteful."*
- **RT-safe:** no allocation, no I/O, no lock in `process()`; buffers sized at voice
  allocation or at the off-audio-thread reload, on `pitch_shift`'s existing pre-warm
  precedent.
- **Per-voice state, holding up at the 32-voice ceiling.** The gate is 32 simultaneous
  Preserve voices at 50 % and 200 %, not one voice at 100 %.
- **No new third-party dependency** (`pitch_shift`'s standing property).
- **No dispatch on the per-sample path** — concrete, inlineable types; no `IStretcher`.
- **Onset behaviour is a regression surface.** GA2 eliminated Preserve's ~25 ms onset latency
  by priming the ring with the actual upcoming source. **A stretcher that reintroduces an
  onset delay or a first-frame smear is a regression, not a trade-off.**

**Acceptance criteria.**
- **Rate 100 % with no shift is bit-identical to the un-stretched read.**
- Preserve speaks on frame 0 — no added onset latency, no first-frame smear, in any
  rate/shift combination.
- No audible metallic or phasey artefacting on sustained tonal material at ±6 st and
  75–133 % rate; transient material at 50 % / 200 % is no worse smeared than the interim path.
- The Gate sustain-loop contract is unchanged: **loop the source, shift the output** — loop
  points remain source-frame facts.
- **Measure and report before the algorithm is final:** per-voice CPU at 32 voices, added
  latency (must be zero at the onset), and A/B recordings against the interim path on three
  material classes (one-shot, tonal sustain, full-mix bounce). Report to Daniel; the choice
  is not final until he has heard the A/Bs.

**Open questions.** **[propose, with a measurement step]** the algorithm family itself.
**[verify]** that `core/instrument/CLAUDE.md`'s *"`WDL_Resampler` is not a Preserve engine —
never wire it as the duration-preserving path"* is honoured: Rate legitimately changes
duration under Preserve, so a resampled read is an explicit duration control, but the
*pitch-preserving* mechanism must not be a resampler.

---

## Traceability — all seventeen items

The check that nothing was dropped. Every row points at a track that exists above.

| # | Item (short) | Phase-Wave-Track | Worktree slug |
|---|---|---|---|
| 1 | Envelope editor: radio switch, curve dials, overlay recolor | Θ-W3-T2 | `pth-w3-t2-staged-envelope-curves` |
| 2 | MM preamp Filter — resonant HP/LP stage | Θ-W1-T3 (DSP) **+** Θ-W2-T1 (integration) | `pth-w1-t3-filter-dsp-port`, `pth-w2-t1-filter-voice-path` |
| 3 | Alternative Spline EGs | Θ-W5-T1 | `pth-w5-t1-spline-egs` |
| 4 | Bug: end-of-sample click, Trigger × Preserve | Θ-W3-T2 | `pth-w3-t2-staged-envelope-curves` |
| 5 | Bug: drag-out sometimes lands without audio | Θ-W1-T2 | `pth-w1-t2-capture-handoff-bugs` |
| 6 | Bug: FX-container drop loses the capture | Θ-W1-T2 | `pth-w1-t2-capture-handoff-bugs` |
| 7 | Stereo waveform shows both channels | Θ-W2-T2 | `pth-w2-t2-stereo-waveform-lanes` |
| 8 | Release anchoring; the Pitch AD becomes AHD | Θ-W3-T2 | `pth-w3-t2-staged-envelope-curves` |
| 9 | Loop points — regression + Gate loop-sustain | Θ-W4-T1 | `pth-w4-t1-gate-loop-sustain` |
| 10 | Knob/label sizing, ms units, double-click reset | Θ-W6-T1 | `pth-w6-t1-legibility-and-antialiasing` |
| 11 | Preview glyph; VELOCITY deck; bipolar curves | Θ-W4-T2 | `pth-w4-t2-velocity-deck-and-bipolar-curves` |
| 12 | Toolbar cleanup; full-width piano strip; tooltips | Θ-W2-T3 | `pth-w2-t3-toolbar-and-piano-strip` |
| 13 | Antialiased rendering audit for high-DPI | Θ-W6-T1 | `pth-w6-t1-legibility-and-antialiasing` |
| 14 | Trigger amp/filter fade → AHD consolidation | Θ-W3-T2 | `pth-w3-t2-staged-envelope-curves` |
| 15 | One-click in-sampler resample | Ξ-W1-T2 (note model) **+** Ξ-W2-T1 (bake chain) **+** Ξ-W3-T1 (popup) | `pxi-w1-t2-note-program-model`, `pxi-w2-t1-resample-bake-chain`, `pxi-w3-t1-capture-signal-popup` |
| 16 | Retire the zone mapping system | Θ-W1-T1 | `pth-w1-t1-zone-retirement` |
| 17 | Consolidate provenance/usage tracking | Ξ-W1-T1 | `pxi-w1-t1-tracking-consolidation` |

### Work in this plan that is not one of the seventeen

The table above is a completeness proof over `TODO-1.0.md` — every row points at a track,
so nothing from the source was dropped. It is deliberately **not** an index of the plan:
work that did not come from the source doc has no row, and inventing one would weaken the
proof it exists to give.

- **Θ-W3-T1 — `live-parameter-delivery`** (`pth-w3-t1-live-parameter-delivery`). Arose
  from Θ-W2-T1's implementation review, not from `TODO-1.0.md`. The first such track in
  this plan; see Θ-W7-T1 below for the second.
- **Θ-W7-T1 — `arc-and-spline-aa`** (`pth-w7-t1-arc-and-spline-aa`). Opened after
  Θ-W6-T1 shipped, when Daniel found two rendering defects by eye in the editor — not
  from `TODO-1.0.md`, and not a track this plan originally scoped. The second such track
  in this plan today; if others appear, they belong on this list rather than in the
  table.
- **All of Phase Γ** (`pg-*`). Seven tracks from a direct interview with Daniel
  (2026-08-01), not from `TODO-1.0.md`. Listed here as a block rather than per track,
  because the whole phase is outside the source doc; the product reasoning lives in
  `docs/product/instrument-control-surface.md` and the automation scoping it defers in
  `docs/product/parameter-automation.md`. Γ-W3-T1 additionally **discharges** the
  `docs/TODO.md` deck-rework entry, whose original "one row of taller decks with
  within-deck stacking" shape Daniel explicitly superseded.

### Deliberate compressions

Recorded so a reader of `TODO-1.0.md` can see what this plan did to the source, rather
than discovering it later:

- **Item 2 is split across two waves.** The DSP port (Θ-W1-T3) is deliberately separated
  from the integration (Θ-W2-T1) so the external-input dependency on Daniel's Cortex-M4
  code sits on a standalone, disjoint track instead of blocking a wave. Item 2's
  acceptance criteria are split accordingly — the range/resonance assertions land in
  W1-T3's tests, the audible/pipeline/deck criteria in W2-T1.
- **Item 2's filter envelope ships twice.** W2-T1 ships it in the existing staged AHDSR
  shape; W3-T2 gives it the curve treatment and the mode-driven Gate→AHDSR /
  Trigger→AHD shape. This is deliberate: waiting would put the filter behind the whole
  envelope system.
- **Item 4 lands in Θ-W3, not Θ-W1.** Its fix region is the region item 14 retires, and
  the only earlier instrument-side track owns the entire engine. Its acceptance gate is
  stated as the post-consolidation gate. It is not gated behind the *whole* editor chain
  — three waves of six — and the source doc itself requires re-verification under the
  surviving mechanism either way.
- **Item 11's filter velocity curve is split from item 2's filter velocity
  modulation.** W2-T1 wires the modulation path (following the amp/pitch precedents);
  W4-T2 sets the curve's bipolar domain and default and homes its button. Neither track
  can do the other's half.
- **Item 15's undo/recovery is carried as a note, not a criterion** — Daniel set it at
  exactly "a plus." The guaranteed recovery floor (the superseded file surviving until
  prune) is a criterion.
- **Nothing else was compressed.** Every other item's behavior bullets and acceptance
  criteria are carried at full strength into the track that owns it.

---

## Outline at a glance

```
Phase Θ — ReaSampler 9000: one parameter set, filter, shapeable envelopes, legible editor
  W1  Collapse and re-seam
      T1 zone-retirement ......................... 16
      T2 capture-handoff-bugs .................... 5, 6
      T3 filter-dsp-port ......................... 2 (DSP)      [needs Daniel's M4 code]
  W2  Filter in the voice path; waveform and chrome bands
      T1 filter-voice-path ....................... 2 (integration)
      T2 stereo-waveform-lanes ................... 7
      T3 toolbar-and-piano-strip ................. 12
  W3  Live parameters, then the staged envelope system      [T1 before T2 — serial]
      T1 live-parameter-delivery ................. (not one of the seventeen)
      T2 staged-envelope-curves .................. 1, 8, 14, 4
  W4  Loop sustain and the velocity deck
      T1 gate-loop-sustain ....................... 9
      T2 velocity-deck-and-bipolar-curves ........ 11
  W5  Spline EGs
      T1 spline-egs .............................. 3
  W6  Editor legibility pass
      T1 legibility-and-antialiasing ............. 10, 13
  W7  Arc-and-spline antialiasing fix
      T1 arc-and-spline-aa ....................... (not one of the seventeen)

Phase Ξ — The resample loop            (W1 concurrency-safe with Θ from Θ-W2 onward)
  W1  Consolidated tracking, and the programmed-note model
      T1 tracking-consolidation .................. 17
      T2 note-program-model ...................... 15 (model)
  W2  The bake chain                      [requires all of Phase Θ, and Phase Γ before it]
      T1 resample-bake-chain ..................... 15 (chain)
  W3  The capture-signal popup
      T1 capture-signal-popup .................... 15 (popup)

Phase Γ — The instrument's control surface        (none of the seventeen; runs before Ξ-W2)
  W1  Foundations                            [3 tracks, disjoint by surface]
      T1 knob-interaction-law ....... modifiers + ms/semitone tapers + reset bypass
      T2 master-bus-audio ........... limiter + meter ballistics + processor   [payload v14]
      T3 contour-trace-curves ....... staged traces draw curved, knot on its trace
  W2  New controls, and the overlay's marks  [2 tracks]
      T1 pitch-rate-deck ............ Rate + Pitch, Varisp/Presrv compounding  [payload v15]
      T2 loop-crossfade-ux .......... four-mark grammar; fade painted where it is heard
  W3  The reflow                             [1 track]
      T1 deck-reflow ................ two rows + double-height MASTER; floor 1190x680
  W4  Preserve time-stretch                  [1 track]
      T1 preserve-time-stretch ...... real stretcher      [measure-and-report gate]
```