docs(TODO-1.0): item 14 — Trigger-mode amp fades replaced by AHD with curves; amp envelope shape follows playback mode

TODO-1.0.md

@@ -2,7 +2,8 @@
 
 Post-1.0 queue for ReaSampler — chiefly the 9000 instrument, plus two
 extension-side bugs. Items 1–3 are the first batch, in Daniel's ordering
-(2026-07-28); items 4–13 are a second batch (2026-07-28, later the same day).
+(2026-07-28); items 4–13 are a second batch (2026-07-28, later the same day);
+item 14 is a third, single-item batch (2026-07-28, later again).
 Deliberately specified at the level of product
 intent, user-visible behavior, and acceptance criteria — **no implementation
 design, no file/module references**. These were authored while Phase Q was
@@ -47,13 +48,25 @@ written.
 
 A **second-batch second follow-up round** (2026-07-28, same day) closed item
 8's last two questions — Hold's 0–100% reference, and the scope of the
-1:1-overlay/combined-bound policy. **With that, no open question anywhere in
+1:1-overlay/combined-bound policy. **With that, no open question then in the
-this doc awaits a Daniel decision.** Everything still marked open is
+doc awaited a Daniel decision.** Everything still marked open in items 1–13 is
 verify-or-propose-at-implementation, not a blocker: item 9's loop-point
 regression verification and its spec details (crossfade units, storage
 confirmation, editing surface — each carries its own resolve-at-review path in
 the item), and item 11's does-a-user-facing-pitch-velocity-curve-already-exist
-check. Nothing is blocked on Daniel.
+check. Nothing in items 1–13 is blocked on Daniel.
+
+A **third batch** (2026-07-28, later again) appends item 14 — a single
+consolidation enhancement: in Trigger mode the amp envelope's
+fade-in-length/fade-out-length pair is replaced by item 8's AHD (with item 1's
+curves), so the amp envelope's staged shape follows the playback mode —
+Gate → AHDSR, Trigger → AHD. Item 8's sustain-stage scope rule then covers the
+amp envelope literally, not just by analogy (a one-line cross-reference is
+added there). Item 14 carries **one question awaiting a Daniel decision** —
+whether item 2's filter AHDSR follows the same mode-driven shape — so the doc
+is no longer decision-clean. Its other open question (stage-value state across
+the Gate/Trigger switch) is propose-at-implementation-review, not
+Daniel-blocking.
 
 Ordering note: item 1's curve/overlay treatment explicitly anticipates item 2's
 filter envelope ("filter to be added"), and item 3 layers on both. They can land
@@ -68,7 +81,10 @@ loop-sustain is a Gate-mode (Staged) feature and composes with item 3's
 Gate-unavailable-in-Spline rule. Item 13 (anti-aliasing audit) touches nearly
 every surface the other items repaint — sequencing it after the layout/knob
 work (1, 8, 10, 11, 12) likely avoids doing the polish twice; that is an
-observation, not a decision.
+observation, not a decision. Item 14 (third batch) rides directly on item 8's
+AHD definition and item 1's curve treatment — cheapest folded into or
+immediately after that combined work — and repaints amp-deck/overlay surface
+that items 10 and 13 later polish.
 
 ---
 
@@ -638,7 +654,9 @@ change that turns the pitch envelope from AD into AHD**.
   into or immediately after that work; item 1's sloped-segment rule reads
   Attack and Decay for the pitch AHD (Hold is flat, no curve dial). Item 3's
   Spline overlays are unaffected by construction: a spline always spans the
-  full sample width already.
+  full sample width already. Item 14 extends the AHD to the amp envelope's
+  Trigger mode, so this scope rule selects by the envelope's current shape
+  under the active playback mode — see item 14.
 
 **Open questions.**
 
@@ -904,3 +922,104 @@ high-DPI, high-resolution displays. Daniel named the visibly pixely surfaces:
 - The audit produces a short disposition list: surfaces checked, which needed
   work, which were already clean.
 - Daniel signs off by eye on the named surfaces.
+
+---
+
+## 14 — Enhancement: Trigger-mode amp envelope — fade-in/fade-out replaced by the AHD (with curves)
+
+**Daniel's ask (verbatim, 2026-07-28).**
+
+> the amp env trigger mode fade in length fade out changes to the AHD envelope
+> (with curves of course), to reduce code for the same thing, and consolidate
+> under the new design.
+
+**Intent.** Consolidation. In Trigger mode the amp envelope's fade-in-length /
+fade-out-length pair is retired and replaced by the same three-stage
+Attack → Hold → Decay envelope item 8 specifies for the pitch envelope — with
+item 1's per-segment curves. Daniel's stated motive is reducing code for the
+same job: one staged-envelope design covering what is currently two separate
+mechanisms doing the same thing. The product consequence: **the amp envelope's
+staged shape follows the playback mode** — Gate → AHDSR (sustain,
+right-anchored release, per item 8); Trigger → AHD (sustain-less).
+
+**Behavior.**
+
+- **Trigger mode: fades out, AHD in.** In Trigger mode the amp envelope is an
+  AHD per item 8's definition: Hold spans 0–100% of the time remaining after
+  Attack and Decay, so A + H + D ≤ sample length holds by construction and the
+  overlay is 1:1 with the waveform's time axis. The fade-in-length and
+  fade-out-length controls go away in Trigger mode; Attack and Decay carry
+  those roles under the new design.
+- **With curves.** The Trigger AHD's sloped segments — Attack and Decay; Hold
+  is flat, as everywhere — get item 1's full curve treatment: exponent 0.1–10,
+  inner dials, mid-segment overlay knots, tertiary-purple rendering.
+- **Gate mode unchanged.** In Gate mode the amp envelope remains the AHDSR
+  with item 8's right-anchored release. Item 9's loop-sustain spec (a
+  Gate-mode feature) is untouched.
+- **Item 8's scope rule now covers the amp envelope literally.** Item 8
+  settled that the 1:1-overlay property and the by-construction combined-time
+  bound apply to envelopes **without a sustain stage**, and the
+  right-anchored-release policy to those **with** one — Daniel's rationale:
+  "the 1:1 mapping only makes sense for trigger, not gated envelopes." With
+  this item the amp envelope in Trigger mode *is* sustain-less, so it takes
+  the 1:1 time-mapped overlay automatically; in Gate mode it keeps the
+  right-anchored release. The rationale now describes the amp envelope
+  directly, not just by analogy: the rule selects by the envelope's **current
+  shape under the active playback mode**, not by which processor the envelope
+  modulates. No new rule is needed — item 8's rule already decides both cases.
+- **Pre-existing instances reopen sounding identical.** The doc's standing
+  migration framing (items 1, 2, 11) applies: a project saved before this
+  change reopens with unchanged audible behavior — in particular, a Trigger
+  instance's prior fade-in/fade-out contour is reproduced by the loaded AHD.
+  The evident mapping (Attack ← fade-in, Decay ← fade-out, Hold ← the full
+  remainder, curve exponents at whatever value reproduces the prior fade
+  shape) is a verify-at-implementation detail, not a Daniel call; the gate
+  below states the requirement. A prior zero fade-out is Decay = 0 — the
+  abrupt end stays representable, so nothing the old controls could express
+  is lost.
+- **Cross-references.** Item 8 supplies the AHD definition and the scope rule
+  (this item is that rule's second consumer); item 1 supplies the curves —
+  sequencing: cheapest folded into or immediately after that combined work.
+  Item 3 is unaffected in Spline mode (a spline already plays as a
+  full-sample-length time function — the trigger model); its "save but
+  inactive" dual-state precedent bears on the second open question below.
+  Item 4's Trigger × Preserve end-of-sample click sits in the region the
+  fade-out currently governs — whichever of the two lands first, item 4's
+  gate must be re-verified under the surviving mechanism.
+
+**Open questions.**
+
+- **Does the filter AHDSR follow the same mode-driven shape?** Item 2's
+  filter envelope is the same staged machinery, so Gate → AHDSR /
+  Trigger → AHD would extend naturally — but Daniel said this only for the
+  amp envelope, and it is not asserted here. **Awaits a Daniel decision** —
+  currently the doc's only Daniel-pending question.
+- **Stage-value state across the Gate/Trigger switch — shared or per-mode?**
+  The Gate AHDSR and Trigger AHD share stage names (A, H, D); whether they
+  share *values* (one envelope whose S and R fall away in Trigger) or keep
+  per-mode state (item 3's "save but inactive" dual-state precedent) is
+  unspecified. Migration leans per-mode: an old instance carries both its
+  AHDSR values and its Trigger fade values, and a shared-value model cannot
+  preserve both modes' prior sound at once. Resolve at implementation review
+  with a proposal — not Daniel-blocking, but the sound-identical gate must
+  hold for whichever mode a saved instance plays in.
+
+**Acceptance criteria.**
+
+- In Trigger mode the amp deck shows Attack / Hold / Decay — no fade-in or
+  fade-out control anywhere in Trigger mode — with curve inner dials on
+  Attack and Decay and none on Hold; when the amp envelope is overlay-active
+  (item 1's radio), its overlay is 1:1 with the waveform time axis, and no
+  combination of A, H, D settings exceeds the sample length (Hold = 100%
+  exactly fills it — by construction, no clamp).
+- In Gate mode the amp envelope is the unchanged AHDSR: sustain stage,
+  right-anchored release per item 8.
+- Switching between Gate and Trigger playback switches the amp envelope
+  surface (deck and overlay) between AHDSR and AHD accordingly.
+- A project saved before this change reopens sounding identical: a Trigger
+  instance's prior fade-in/fade-out contour — including a zero fade-out's
+  abrupt end — is audibly reproduced by the loaded AHD.
+- The Trigger amp AHD behaves stage-for-stage like item 8's pitch AHD — Hold
+  semantics, curve treatment, and overlay mapping match. (This is the
+  observable proxy for the consolidation motive: one staged-envelope design,
+  two consumers.)