[twarp 07b] Claude Code panel: panel shell + ported transcript

[timomak]

twarp 07b — Claude Code panel: panel shell + ported transcript

Sub-phase 7b of feature 07. Brings back the rendering layer of Warp's Agent Mode as a left-panel tab, by porting the deleted ai_assistant transcript renderer and reparenting it onto the thin claude_code::Transcript model. No live claude process yet — 7b is fed by a synthetic event source so the ported renderer is testable end-to-end; the live driver lands in 7c.

This is a rendering-layer-only revival. Feature 02 removed Warp's AI service (accounts, LLM clients, billing, cloud conversation storage); none of that comes back here. twarp adds no account, no LLM client, no cloud sync — the panel only ever renders a transcript, and (from 7c on) talks solely to the local claude CLI the user already runs.

Why a port, not a rebuild

PR #67 rebuilt the panel from Flex/Container/Link primitives and was abandoned for it (TECH.md §Postmortem). This PR follows the re-spec's per-file decision matrix:

• Ported ai_assistant::transcript::render_message's markdown body → render_markdown_body (FormattedTextElement for prose, a bordered monospace box for fenced code).
• Ported the AI-agnostic splitter translate_formatted_text_into_markdown_segments → split_markdown_segments.
• Reused feature 03's live markdown stack (parse_markdown → FormattedTextElement) for §18.
• Assistant text renders as themed markdown (headings, lists, inline code, fenced code blocks, links) — not the plain spans [twarp 07b] Claude Code panel: resurrect view + event model #67 shipped.

Kept from #67 (correct, decoupled)

• crates/claude_code driver crate (Transcript/TranscriptEvent/TranscriptItem + driver + sessions) — 19 unit tests pass.
• Registration scaffolding: ToolPanelView::ClaudeCode, LeftPanelDisplayedTab::ClaudeCode, toolbelt button, render arm, compute_left_panel_views push, and the ⌘⌥K binding via custom_tag_to_keystroke (not with_key_binding — the feature-06 lesson).

Discarded from #67

• The entire primitive claude_code_panel/mod.rs body (rebuilt as a port).
• The WorkspaceAction::ClaudeCodePanel(...) forwarder and its Workspace::handle_action arm. The panel now dispatches its own ClaudeCodePanelAction the GlobalSearchView way — it is a TypedActionView with an on_left_mouse_down focus-grab, so in-panel clicks land without a forwarder.

Behavior delivered (PRODUCT §1–§7, §16–§20, §60)

• Claude Code toolbelt entry + ⌘⌥K toggle (remappable).
• Panel resizes/persists width with the rest of the left panel.
• Zero state when empty; unavailable state (named binary + install hint) when claude is off PATH, replacing the panel.
• Opening the panel starts no subprocess.
• Submitting a message renders a user turn + a representative markdown assistant reply via the ported renderer (synthetic; 7c wires the real driver).

Feature flag decision

Always-on (no flag) — acceptable on a personal fork; the panel degrades cleanly to the unavailable state when claude is absent (§6). Recorded in STATUS.md / TECH.md §Feature flag & rollout.

Testing

• cargo test -p claude_code → 19 passed.
• cargo check -p warp → clean.
• ./script/presubmit is not fully runnable on the owner's Mac (see project notes); relied on cargo check/clippy/fmt + the crate tests.

Smoke test (7b section of PRODUCT.md): steps 1–5 (toolbelt entry, ⌘⌥K toggle, width persistence, zero state + no subprocess, unavailable state) plus the acceptance gate — a submitted message renders in Agent-Mode markdown shape (prose + themed fenced code block), not plain text.

Specs: PRODUCT.md / TECH.md merged in #66 and re-spec #68. Scope here is 7b only; 7c–7h follow.

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