Reviewed as part of the 15-PR edit-panel redesign stack. Full stack review posted on #2120. No blockers on this PR. — Miga

Full Stack Review — Edit Panel Redesign (15 PRs, ~10,700 additions)

Reviewed the entire stack in three tiers: foundation (#2120–#2122), domain groups + retirement (#2123–#2127), and UX polish (#2128–#2190). Per-PR verdicts below; no blockers across the stack.

Tier 1: Foundation (#2120–#2122)

#2120 — flat inspector foundation + Text group — Clean. Introduces the shell (header, footer, accordion, value-tier system, primitives) behind STUDIO_FLAT_INSPECTOR_ENABLED. resolveValueTier is a well-designed single decision point. hideOwnHeading flag on TextSection prevents doubled headings without duplication.

#2121 — Style group — Clean. Each sub-block (Fill, Stroke, Radius, Shadow, Blend, Blur, Overflow, Mask, Opacity) owns exactly one CSS domain. Helpers come from propertyPanelHelpers.ts (single source). FlatRadiusRow reuses legacy BorderRadiusEditor for non-uniform corners — good reuse.

#2122 — Layout + Motion groups — Clean. The standout SSOT contribution of the stack: deriveElementTiming extracts the "how do we compute start/duration?" decision into one function consumed by both Layout's keyframe gutter and Motion's timing row. Fixes a real bug where Layout used elDuration ?? 1 while Motion inferred from tweens.

Tier 2: Domain Groups + Retirement (#2123–#2127)

#2123 — Media group — Clean. Legacy MediaSection fully replaced, not duplicated. FlatToggle is a genuine new primitive.

#2124 — Grade (color grading) — Nit. The useColorGradingController extraction is the strongest SSOT win in the stack — turns a 200-line inline state machine into a shared hook. During the hybrid window both legacy and flat sections instantiate the hook (two debounce timers, two polling cascades). Resolved by #2126.

#2125 — persisted pinning + multi-field Text — Clean. FlatGroupDescriptor[] data model eliminates per-group copy-paste. usePersistedPinnedGroups is a clean single-path persistence hook.

#2126 — retire legacy Style and Grade — Clean. Pure SSOT cleanup — removes the dual-rendering transition state. The hideFlex escape hatch is gone.

#2127 — parity gaps from legacy-retirement audit — Clean. visibleIntensity helper centralizes the "revive from 0% strength" decision. Radius path simplified by always delegating to BorderRadiusEditor. Stroke width clamping reuses existing normalizePanelPxValue. Keyboard accessibility for compare hold button is thorough.

Tier 3: UX Polish (#2128–#2190)

#2128 — sticky accordion headers — Nit. Dual sticky anchoring (top-0 bottom-0) is unconventional but intentional per the design.

#2134 — scroll refactor — Clean. Well-structured three-region layout (before-open, scrollable body, after-open). FlatGroup → FlatGroupHeader rename correctly reflects narrowed responsibility.

#2135 — remove section pinning — Clean. Complete disciplined removal — no orphaned props, no dead code.

#2136 — animate expand/collapse — Clean. justToggledIds mechanism handles the Chromium re-trigger edge case thoughtfully. Respects prefers-reduced-motion. Well-commented.

#2142 — widen slider hit area — Clean. 2px → 20px invisible hit area. Minimal, correct fix.

#2186 — slider drag support — Clean. Pointer capture API is the correct modern approach. Properly layered before the debounce PR.

#2190 — debounce slider drag commits — Clean. Draft/debounce pattern gives instant visual feedback while debouncing commits at 40ms. Flush-on-release ensures final value always commits immediately. Broad test updates across sibling sections show thoroughness.

Cross-Stack Architecture

The stack follows a disciplined pattern:

1. Flag-gated parallel path — flat inspector runs alongside legacy, gated by STUDIO_FLAT_INSPECTOR_ENABLED. No legacy behavior changes.
2. Suppression flags over removal — when a flat group absorbs a legacy section, the legacy gets hideOwnHeading/hideFlex rather than being removed, enabling safe coexistence. Retired cleanly in #2126.
3. Helpers carry new knowledge; primitives carry new rendering — every helper justifies itself with a fact the caller doesn't know. No trivial wrappers.
4. Self-correcting SSOT — #2122 identifies and fixes the timing-basis disagreement that would have been an SSOT violation across Layout and Motion. The stack improves as it progresses.

CI: 0 failures across all 15 PRs. Ship the stack.

— Miga

Blocker on current head 444639d: GitHub reports this PR as CONFLICTING / mergeState DIRTY. Resolve the branch against its stack/base and rerun the required checks before approval. The code review findings are non-blocking, but this head is not mergeable as submitted.

Re-review after rebase: current head 6e9d99ef8f3aec054aebd05c9b2201f15aec4665 is mergeable, required checks have no failures/pending checks, and prior conflict blocker is resolved. No unresolved review threads; foundation/value-tier and cross-stack contracts remain clean.

Superseding earlier approval: the latest max-review pass found confirmed correctness issues in this flat-inspector stack (identity/selector-index state, hide-all write races, timing inference, slider pointer/keyboard/reset semantics, and duplicate React keys). Hold merge and require fixes plus re-review on the current stack head.