tracking: align MCP CLI UX with TUI design doc

[esengine]

Why

An audit against docs/design/agent-tui-terminal.html (sections 24 · MCP browser, 32 · slow-server toast, 37 · MCP lifecycle) shows the runtime UX has drifted from the documented design.

design says	runtime does	gap
Interactive /mcp browser modal — ↑↓ pick, ⏎ inspect, r reconnect, d disable	/mcp is a text dump into scrollback	no modal
Six lifecycle one-liners on state changes: ↻ handshake… / ✓ connected / ◌ slow / ↻ reconnect 2/5 / ✖ failed / ○ disabled	Two startup-only lines: ▸ MCP[label]: N tool(s)… and ▸ MCP setup SKIPPED…	wrong vocab + 4 missing states
/mcp disable / enable / reconnect slash subcommands	none	missing
p95 slow-call detection + toast (⚠ MCP \notion` slow · 8.4s p95 over the last 5 calls`)	one-shot elapsedMs at startup only	no runtime tracking

Stages

Stage A — Lifecycle vocabulary alignment

Reshape the existing startup-time strings to match design §37 byte-for-byte. No new lifecycle states wired this stage — just the three that already fire (handshake… pre-bridge, connected post-bridge, failed in the catch).

Touch:

• src/cli/commands/chat.tsx:206-277 (the for (const raw of requestedSpecs) loop)
• src/cli/commands/run.ts:90-115 (same pattern)
• New src/cli/ui/mcp-lifecycle.ts exporting formatMcpLifecycleEvent({ name, state, detail }) so chat / run / future code share the formatter

Acceptance:

• Output matches design §37 layout (⌘ MCP · <name> ✓ connected 12 tools · 8 resources · 142ms)
• Three states emit now: handshake… (before bridge), connected (after bridge with counts + ms), failed (catch path with reason)
• Snapshot test in tests/mcp-lifecycle.test.ts pinning the formatter

Estimate: 2-3 hours.

Stage B — /mcp interactive browser

Replace the text-dump /mcp with a keyboard-driven modal matching design §24. Layout per the mockup; r and d are visible-but-stub keybinds in this stage (active in Stage C).

Touch:

• New src/cli/ui/McpBrowser.tsx wrapping the existing Select.tsx for picker behavior
• src/cli/ui/App.tsx — add modal slot + mcpBrowserOpen state
• src/cli/ui/slash/handlers/mcp.ts — flip /mcp from returning { info: ... } to setting modal state
• Keep the rich text dump as a non-TTY / replay fallback

Acceptance:

• /mcp opens the modal; Esc closes it
• ↑↓ navigates rows; ⏎ is a no-op stub (Stage D will do tool inspection)
• All four health badges render: ● healthy, ◌ slow, ✗ failed, ○ disabled
• Layout traces back to design §24 line-for-line

Depends on: Stage A (the lifecycle formatter is reused for row health text).

Estimate: 1 day.

Stage C — /mcp disable / enable / reconnect + slow-toast

Three slash subcommands and the p95 latency tracker that drives the warn toast.

Subcommands:

• /mcp disable <name> — write disabled: true to the server's config entry; emit ○ disabled lifecycle card; bridge skips it on next session and the r key in the browser flips it back
• /mcp enable <name> — inverse
• /mcp reconnect <name> — tear down the live McpClient, re-handshake, re-bridge; emits ↻ reconnect N/5 then either ✓ connected or ✖ failed

Slow detection:

• Wrap dispatch in src/mcp/registry.ts to record per-tool elapsed_ms in a per-server ring buffer (size 5)
• After 5 calls, compute p95; if > mcpSlowThresholdMs (default 4000), emit toast ⚠ MCP \` slow · 8.4s p95 over the last 5 calls`
• Idempotent within a turn (don't re-emit on every call)

Touch:

• src/config.ts — disabled?: boolean per MCP entry, mcpSlowThresholdMs?: number global
• src/mcp/registry.ts — latency ring buffer + p95 helper
• New src/cli/ui/slash/handlers/mcp-control.ts for the three subcommands
• New src/cli/ui/mcp-toast.ts for the warn emission

Acceptance:

• All three subcommands work in current session (dynamic teardown matters for reconnect)
• Slow toast fires after p95 threshold and is idempotent per turn
• /mcp browse reflects updated state without restart

Depends on: A (lifecycle vocab), B (browser surface for live state).

Estimate: 1.5-2 days.

Stage D — (defer) tools sub-pane on browser ⏎

Inside the browser, ⏎ on a server opens its tools / resources / prompts list. Deferred because reasonix mcp inspect <spec> already covers this from the CLI; in-browser inspection is polish, not core. Pull in 0.21.1 if there's demand.

Constraints

• One stage per PR. Stage A unblocks the consistent lifecycle vocabulary that B and C reuse.
• All PRs in this stack reference this issue with Closes part of #<this>.
• Every visual element must trace back to a section number in docs/design/agent-tui-terminal.html. No design-token improvisation.

Versioning

Stages A + B + C target 0.21.0. Stage D may slip to 0.21.1.

[esengine]

Stage status:

• Stage A — lifecycle vocabulary alignment · #106 (merged)
• Stage B — interactive /mcp browser modal · #107 (merged)
• Stage C1 — /mcp disable / enable + disabled lifecycle event · #108 (merged)
• Stage C2a — p95 latency tracker + slow-server warn toast · #109 (merged)
• Stage C2b — /mcp reconnect <name> — split out as RFC RFC: /mcp reconnect <name> — live teardown without breaking the cache prefix #110 because the live tool-list swap raises a cache-prefix invariant question that needs a design call before code

What ships in 0.21.0: A + B + C1 + C2a (this issue, minus the r keybind in the browser which is still a stub pending #110).

What waits for the RFC: r keybind activation, /mcp reconnect <name> slash subcommand, the ↻ reconnect N/5 lifecycle line.