Status: SHIPPED 2026-09-17 (branch feat/p9-w15-commands, daemon 0.20.0-p9w15). Ground truth: research-phase-9-w14-w15-plan-commands.md (adapter-source-verified) + the rig captures noted inside.

The ACP available_commands_update push carries the agent's slash-command catalog — claude-code (after new/load/resume; custom + MCP commands renamed mcp:<name>), codex-acp (review / review-branch / review-commit / init / compact / logout, with input.hint on the review family), and opencode (its Command.Info list — which includes platform-deployed command/*.md custom commands). dsh/hermes never push one. Today the daemon maps it to raw and the web drops it: the portal user has no way to discover or invoke the agent's commands.

Invocation needs NO new protocol: a command runs as an ordinary session/prompt whose text is /name rest-of-line (verified for all three adapters in the research doc — claude's CLI parses slash text, codex's thread handles it, opencode's detectSlashCommand matches the pushed names and routes to its internal session.command).

Additive stream kind (bounded view of the adapter push):

export const availableCommandViewSchema = z.object({
  name: z.string().min(1).max(128), // VERBATIM adapter name (may be 'mcp:foo')
  description: z.string().max(512), // clamped daemon-side
  hint: z.string().max(256).optional(), // from input.hint (args placeholder)
});
// chatStreamEventSchema +=
z.object({ kind: z.literal('commands'), commands: z.array(availableCommandViewSchema).max(64) });

Replace semantics (the push always carries the full catalog). Riding the ordinary stream gives it the history ring + resync replay for free; the claude wrapper pushes AFTER session/load replay (deliberately), so a rejoined channel re-receives it live.

One new arm in mapAcpUpdate: case 'available_commands_update' → takeAvailableCommands(update.availableCommands) (≤64 rows, name ≤128, description clamped 512, input.hint clamped 256, malformed rows skipped) → {kind:'commands', commands}. Stateless, like plan. DAEMON_VERSION → 0.20.0-p9w15.

• fold.ts: FoldState.commands: CommandView[] (starts []; replace on event; history rebuild converges).
• Composer /-palette (portal-reference behavior, Signal-styled):
  • Opens while the draft starts with /, commands exist, the channel is ready and no turn is running. The FIRST word after / filters (name OR description substring); the palette stays open while typing args.
  • Rows: /{name} (mono) + description + the args hint (muted).
  • Keyboard: ↑/↓ cycle (wrapping), Esc closes, bare Enter SELECTS the active row and fills /name (focus stays; the user reviews then sends), Enter with a space after the first word sends as a normal prompt. Click selects. isComposing guards IME as everywhere else.
  • Positioned as a popover ABOVE the composer card (absolute; the card must not clip it), width matching the card, capped height with scroll, role="listbox" + aria-activedescendant.
• No fallback table. An agent that never pushed commands shows no palette (dsh, hermes) — same data-driven honesty as the W9 selectors. The portal reference ships a hardcoded fallback list; we deliberately don't.
• The empty-filter state shows a muted "no matching commands" row (palette stays open so the user sees why).

• Structured command input (input.hint is display-only — ACP 1.4 has only the unstructured kind), command history/autocomplete beyond the filter, server-side command storage (the catalog is per-channel session state).

• shared: schema cases (accept, bad kind, cap).
• cli: mapAcpUpdate cases (verbatim names incl. mcp:, hint extraction, clamp, malformed drop, empty catalog passes as cleared) + fixture round trip — the fixture gains a FIXTURE_COMMANDS=1 arm pushing a small catalog after session/new (one command with a hint, one without).
• web: fold arm mirrors plan's state-only merge (no component harness); palette interaction verified on the rig.

• Catalogs, all four targets: codex 6 (review + input.hint, review-branch, review-commit, init, compact, logout); claude-code 46 (incl. deep-research AND the emitter-installed cc-test-kit:… plugin commands — platform-deployed commands surface through the agent's own catalog; mcp:/plugin names ride verbatim); opencode 3 (init, review, customize-opencode); dsh NONE — typing / shows no palette.
• Palette (browser): opens on /; first-word filter (/ini narrows to exactly /init; a non-matching prefix shows the 无匹配命令 empty state); ArrowUp/ArrowDown cycle; bare Enter SELECTS and fills /name (trailing space verified); click selects.
• Execution E2E: /review sent as a plain prompt → codex ran its review command (1m17s turn, honest verdict — the rig container has no bubblewrap so its sandbox can't launch; environment limit, not a pipeline issue; clean turn end, composer re-enabled).

pickCommand filled /name but never dismissed the palette — and the keyword-change effect reset paletteDismissed right back, so the list kept showing after every commit until Escape. Now every commit (bare Enter, mouse click, and NEW: Tab while the palette is open) marks the keyword it filled (a ref, so the reopen-on-new-keyword rule survives), fills the Sender, and closes the palette — the filled text in the Sender is the review affordance. Escape semantics unchanged; typing a new /-keyword reopens as before.