#24020 cmux NEXT Inspector: over the chat it is a card as tall as its sections, not a full-height column

Leo, 2026-10-22: "THIS BECAME A SIDEBAR FOR NO REASON, ALL THIS DEAD SPACE".

Cause. Over the chat (the overlay placement, the default), the Inspector was a column from under the chat header to the pane's foot (top: var(--acpmux-inspector-top) … bottom: 0), added in #22643. #23477 made that column liquid glass, so its empty foot showed as a slab of glass taller than its sections, about 1200 px in Leo's window.

Fix (inspector.css only). Over the chat, the Inspector is a card anchored under its toggle and as tall as its sections:

• No bottom: 0. Its height comes from its content, and the body is flex: 0 1 auto.
• max-height stops it 8 px above the pane's foot. Past that, its body scrolls, as before.
• An 8 px inset from the right edge, and a 14 px radius.
• The pushed column (the Push setting) is unchanged.

Test (red first). webviews/test/chat-inspector-overlay-toggle.test.ts, in real Chromium and WebKit:

• In a 1400 px pane, the panel's foot is within 16 px of its last section, and well above the pane's foot.
• In a 160 px pane, it stays inside the pane and its body scrolls.
• Red at b50678d2 with the base CSS: deadSpace: false in both engines.
• Green at 70c6e498: all 6 tests in the file pass, and the inspector motion, reveal and unit tests pass too (29 pass).

Capture. Before/after, same harness, 1100×820, Inspector open:

• Before: the glass column runs from under the header to the window's foot, with about 620 px of empty glass below Context.
• After: a card that ends 10 px under Context; the transcript shows below it.
• The webview gallery run in CI attaches the screenshots.

Counts. The "5 running" subagent count is a separate cause: a foreground subagent whose turn completed normally keeps reading running (subagentsLeft in subagents/subagentFold.ts ends them only on a cancelled or lost turn). Counts and rows come from one source and agree. That fix gets its own PR.

🤖 Generated with Claude Code

Agent session: huge-blue

---

^{Need help on this PR? Tag @codesmith-bot with what you need.}

---

Summary by cubic

Fixes the cmux NEXT Inspector over the chat, which ran from under the chat header to the pane's foot and showed a slab of empty glass below its sections. It is now a card as tall as its sections, anchored under its toggle, stopping 8 px above the pane's foot and scrolling when its sections are taller. The pushed-column placement is unchanged.