feat: overview dynamic height for multi-agent sessions (+ #114 grip pill)

[lis186]

繁體中文摘要

多 agent session(4–6 lanes)時,overview 固定 28px canvas 讓每條 lane 只剩 2–3px,活動分布幾乎不可見。本 PR:

1. Overview 高度隨 lane 數動態:canvas 高 = clamp(28, lanes×7+6, 48)。單 lane session 維持 28px 不浪費垂直空間;4–6 lanes 升到 34–48px,每條 lane 得到 ~6px bar(原本 3px)
2. 暗背景可見度:未選中 lane alpha 0.5→0.65(教訓總表 fix: count skill invocations from all 3 trigger paths #2「深色背景吃掉低亮度信號」)、min bar width 0.5→1px、bar 高上限 6→8px
3. fix: swimlane readability — lane height, font sizes, resize handle, minimap #114 收尾:#wf-resize 4→8px + 永久顯示的 grip pill(原本 hover 才有回饋)

否決的方向:sub-agent 聚合活動帶(直接消滅使用者要觀察的 per-agent 分布)、per-lane 對齊左側 lane 標籤(等於把 swimlane 複製進 overview,P13 同款職責重疊)。>10 lanes 時 bar 回到 2px floor——接受,per-lane 分析是泳道的職責,overview 只管全局定位。

Zone 三色、brush-zoom / viewport 拖移 / 邊緣 resize / click 選 turn / accent cursor 全部保留(互動程式碼讀 live canvas 的 MW/MH,自動適應)。

Overview height

Before (fixed 28px, 6 lanes)         After (dynamic, 6 lanes -> 48px)
┌────────────────────────────┐       ┌────────────────────────────┐
│ ▪▪ ▪   ▪▪▪  (2-3px each)   │       │ ▮▮ ▮    ▮▮▮▮   ▮▮  (6px)   │
│ ·· ·    ···  barely visible│       │ ▮▮ ▮▮                      │
└────────────────────────────┘       │   ▮▮   ▮▮▮                 │
                                     │      ▮       ▮▮            │
1 lane  -> 28px (unchanged)          │   ▮▮▮  ▮                   │
4 lanes -> 34px                      │        ▮▮▮▮                │
6 lanes -> 48px (cap, #114)          └────────────────────────────┘
18 lanes -> 48px, bars floor at 2px

Details (EN)

• wfOverviewHeight(laneCount) = min(48, max(28, laneCount*7+6)); applied via canvas.style.height at the top of wfRenderOverview, so it re-adapts on every render (session switch, streaming lane additions) with no extra plumbing
• Bar height formula cap raised 6→8: single-lane sessions get an 8px band, 6 lanes ≈ 6.3px, 18-lane extreme sessions floor at 2px (accepted — the overview is global positioning; per-lane analysis is the swimlane's job, same responsibility split as P13)
• Unselected-lane alpha 0.65 (was 0.5, sank into #161b22); selected stays 0.9 so the selected-lane emphasis survives
• All overview interactions untouched: they parameterize on MW/MH read from the live canvas
• #wf-resize: 8px tall, permanent centered grip pill (::after, 32×3px, var(--border) → var(--dim) on hover)
• Docs synced: docs/workflow-view-design.md (Overview Bar section + P12 form table), prototype/swimlane/DESIGN-DECISIONS.md decision 23

Verification

• Unit: wfOverviewHeight clamp cases in test/workflow-timeline.test.js (14/14 pass); full suite 979/980 — the 1 fail is the known flaky test: codex-adapter rate_limits fixture fails intermittently (expected 1, got 0) #119 codex-adapter fixture time bomb, unrelated
• Browser smoke (isolated CCXRAY_HOME, port 5602, real logs incl. session 157c0faa 482 turns / 6 lanes):
  • 6-lane session → 48px canvas, ~6px per-lane bars, distribution readable
  • 2-lane session → 28px (compact case preserved)
  • Brush-to-zoom, viewport pan, edge resize, small-brush click-select, selection cursor, duration badge — all verified working post-change
  • Grip pill visible on #wf-resize without hover

Closes #114

[lis186]

Codex review trail

• R1: 2 findings — (Medium) barH floor 2 + fixed 1px gap clipped trailing lanes once laneCount*3 > MH (pre-existing at 28px too: 9+ lanes clipped); fixed via wfOverviewBarGeom gap compression + regression test. (Low) stale doc sizes (4px resize / 32px overview) synced.
• R2: R1 confirmed resolved; (Low) "2-8px" wording vs 1px floor — aligned.
• R3: (Low) docs/design-principles.md layout-stability line contradicted dynamic height — qualified as session-level property (rapid agent/turn clicks still never resize).
• R4: (Medium) _wfNearestTurn start-x-only hit test misses clicks inside long bars — pre-existing from PR feat: v8 ctx-split swimlane — dashboard integration (#91) #124, zero occurrences in this diff; filed fix: swimlane click/hover hit-test measures distance to turn start only, misses inside long bars #126, out of scope here.
• R5: PASS.