#3765 was closed unmerged in favor of #3771 (its rebased form), which has now
landed. Update the v26.6.4 SmartMTR ref so the changelog points at the PR that
is actually in the history.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

…#3772)

Release-prep for **v26.6.4**. Docs/metadata only — no code changes.

## CHANGELOG
New `## [v26.6.4]` entry built from the **80 commits** since v26.6.3, in
the house style (headline + New features / CAT-rigctld parity / Fixes &
hardening / Internal / Governance / Packaging). Headlines: KiwiSDR
public-receiver browser, SmartMTR meter view, agent automation/test
bridge, GPU-composite slice flags + multi-GPU selector, accessibility
pass, CAT/rigctld parity, Constitution v2.0.0. `[Unreleased]` preserved
above it.

## Version bump → 26.6.4
`CMakeLists.txt`, `README.md`, `AGENTS.md` (kept in sync), plus a new
`<release version="26.6.4">` in the AppStream metainfo.

## Doc refresh
- **README**: KiwiSDR highlight added; SmartMTR +
multi-GPU/GPU-composite folded into existing highlights.
- **ROADMAP**: retargeted to post-v26.6.4; dropped already-shipped items
wrongly listed in-flight/queued (H1 Phase 2, L1–L4, RigctlPty);
"Recently shipped" refreshed with the v26.6.4 set; added Flathub +
KiwiSDR-followup forward items.
- **AGENTS**: KiwiSDR subsystem pointer added (the one new subsystem
with no mention); constitution principle numbering verified intact
post-v2.0.0.

## Notes
- Release date stamped **2026-06-23** in CHANGELOG + metainfo — adjust
if tagged on another day.
- Provenance language kept out of the release-facing docs
(CHANGELOG/README/ROADMAP) intentionally; the internal clean-room
practice stays documented in CONSTITUTION/AGENTS/CONTRIBUTING.
- The CHANGELOG SmartMTR line lists #3765 — land #3771 (its rebased
form) before tagging so that ref is accurate.

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---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

… truth (#3773) (#3775)

## Summary

Closes #3773. Consistency follow-up to #3771.

#3771 introduced `m_meterMenuOpen` as the explicit open-state for the
SmartMTR meter selector and switched the `paintEvent` underline onto it
(the child `m_meterMenuRow->isVisible()` reads false while the flag is
hidden and rasterized into a GPU sprite). This retires the two remaining
`m_meterMenuRow->isVisible()` reads of the same logical open-state:

- [VfoWidget.cpp:525](src/gui/VfoWidget.cpp#L525) — meter-strip
click-to-toggle → `setMeterMenuOpen(!m_meterMenuOpen)`
- [VfoWidget.cpp:2514](src/gui/VfoWidget.cpp#L2514) —
open-a-tab-closes-the-selector → `if (m_meterMenuOpen)`

Both are live-flag interaction paths, so `isVisible()` was accurate
there and there is **no behavior change** — this just makes
`m_meterMenuOpen` the single source of truth so the two reads can't ever
disagree with the flag the way `paintEvent` did.

The null-guard dropped at the tab path is safe: `setMeterMenuOpen()`
early-returns on a null `m_meterMenuRow`, and `m_meterMenuOpen` is only
set true *after* that guard, so a true value implies the row exists.

## Test plan

- [x] Local build passes (`cmake --build build --target AetherSDR`)
- [ ] Existing tests pass (CI)
- [ ] Manual: meter-strip click toggles the selector; opening a tab
still closes it; underline unaffected

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Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

…ve (#3777) (#3806)

## Summary

**Strategy B** of the GPU-flag reversion plan (attached to #3777) — the
**full excision** that #3803 (the one-line default-flip) was the
reversible precursor to. VFO slice flags are now **unconditionally live
child widgets**; the off-screen-sprite + live-on-hover machinery is
removed entirely, fixing the #3777 idle-flag blur and the Diversity-mode
RX-antenna regression at the source.

**Net −582 lines** across `SpectrumWidget.{cpp,h}` and
`VfoWidget.{cpp,h}`.

## Relationship to #3803
These are **alternatives — merge one, not both.** #3803 flips the
default but keeps the sprite path behind `AETHER_GPU_FLAGS=1`
(reversible, for measurement). This PR deletes the machinery (no env
opt-in remains). Recommended sequence: validate live-flag behavior + the
4-panadapter re-profile via #3803 first; if the group commits to it,
merge **this** as the clean removal and close #3803.

## Removed (all sprite-path)
- SpectrumWidget: `m_gpuFlagMode` + the env gate, `m_flagRefreshTimer` +
lambda, `grabFlagSprites`/`releaseFlagSprite`,
`setLiveFlag`/`updateLiveFlag`,
`updateFlagRefreshTimer`/`attachFlagTimerWindowWatcher` +
`m_flagTimerFilteredWindow`, `FlagSprite` +
`m_flagSprites`/`m_flagDrawOrder`/`m_flagQuadVbo`/`m_flagSampler`/`kMaxFlagSprites`,
the `renderGpuFrame` sprite draw-order/texture/quad blocks, and the QRhi
flag-resource init/teardown.
- VfoWidget: `setButtonsOccluded` +
`m_occludeRestore`/`m_buttonsOccluded`.

## Kept intact (verified)
- **`repositionVfoFlags()`** — the *shared* positioner that calls
`updatePosition()` on every flag; only its trailing GPU-mode hide-block
was removed. Still called each frame from `renderGpuFrame`, so live
flags position correctly. This was the key correctness invariant.
- The whole **GPU panadapter** path (`AETHER_GPU_SPECTRUM`:
FFT/waterfall/overlay) — untouched.
- The **SmartMTR** render-mode-agnostic fixes from #3771/#3773/#3775.
- `event()`/`eventFilter()` non-flag logic (`setMouseTracking`, Mac QRhi
teardown in `prepareForTopLevelChange`) preserved.

## Trade-off (unchanged from #3803)
Re-introduces the #3617 main-thread composite cost #3695 removed
(**~0.82 vs 0.45 cores, +0.37 ≈ +45% main-thread**). Separate from and
likely additive to #3797.

## Test plan
- [x] Builds clean (`cmake --build build --target AetherSDR`); zero
dangling references to removed symbols
- [ ] Idle VFO-flag text crisp; no hover-pop (Windows)
- [ ] Diversity-mode RX-antenna selection works
- [ ] Flags position/move correctly with 1, 2, and N panadapters;
split-partner side-locking intact (repositionVfoFlags path)
- [ ] Dragging a flag: no audio crackle / re-raster crash (#3695's
original concern)
- [ ] 4-panadapter main-thread CPU re-profile (the decision gate)
- [ ] a11y linter clean; SmartMTR meter renders correctly

Refs #3777, #3617. Supersedes #3803. Plan: see the #3777 comment.

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Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>