web(coder): provider settings UI — Settings → Providers tab, picker filter, ACP catalog

v2.3 Phase 5. Provider management lives in Settings → Providers: lists every
registered provider with a status badge, enable/disable toggle (sends the full
override so a custom ACP entry's command survives the wholesale-replace PATCH),
per-provider refresh, and a plaintext diagnostic. The composer provider picker
now filters to enabled && (status==='ready' || 'loading') — disabled/unavailable
providers leave the picker and are managed only in settings; native boocode
always shows. Adds a curated ACP catalog + AddProviderModal (PATCH config then
subset refresh; the modal caps to the viewport with a single overscroll-contain
scroll region). Loading state uses a capped client poll (no WS frame).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/web/src/data/acp-provider-catalog.ts

@@ -0,0 +1,83 @@
+import type { ProviderConfigPatch } from '@/api/types';
+
+/**
+ * v2.3 Phase 5 (design.md §7.3) — a SMALL curated catalog of ACP coding agents
+ * the user might register. We deliberately do NOT port Paseo's 30+ entry list.
+ *
+ * Non-goal: we never install anything. Each entry is a manual-install hint
+ * (`installUrl` / `installCmd`) plus the config `command` that gets written into
+ * `/data/coder-providers.json`. The user installs the CLI themselves; until the
+ * binary is on PATH the provider shows as "Not installed". Commands are
+ * editable after adding — versions are aliased/untrimmed on purpose; pin on your
+ * own host once verified.
+ */
+export interface AcpCatalogEntry {
+  id: string;
+  label: string;
+  description: string;
+  /** Config command written verbatim into providers[id].command: [binary, ...args]. */
+  command: [string, ...string[]];
+  /** Where to install the CLI manually — we LINK, never install. */
+  installUrl: string;
+  /** Optional suggested install command, shown as a copyable hint. */
+  installCmd?: string;
+}
+
+export const ACP_PROVIDER_CATALOG: AcpCatalogEntry[] = [
+  {
+    id: 'amp-acp',
+    label: 'Amp',
+    description: 'Sourcegraph Amp — agentic coding CLI with an ACP bridge.',
+    command: ['amp-acp'],
+    installUrl: 'https://ampcode.com/',
+    installCmd: 'npm i -g @sourcegraph/amp',
+  },
+  {
+    id: 'gemini',
+    label: 'Gemini CLI',
+    description: 'Google Gemini CLI in ACP mode (--experimental-acp).',
+    command: ['gemini', '--experimental-acp'],
+    installUrl: 'https://github.com/google-gemini/gemini-cli',
+    installCmd: 'npm i -g @google/gemini-cli',
+  },
+  {
+    id: 'cline',
+    label: 'Cline',
+    description: 'Cline coding agent over ACP (run via npx).',
+    command: ['npx', '-y', 'cline', '--acp'],
+    installUrl: 'https://cline.bot/',
+  },
+  {
+    id: 'claude-code-acp',
+    label: 'Claude Code (ACP)',
+    description: "Zed's ACP adapter for Claude Code — distinct from the built-in PTY claude provider.",
+    command: ['npx', '-y', '@zed-industries/claude-code-acp'],
+    installUrl: 'https://github.com/zed-industries/claude-code-acp',
+  },
+  {
+    id: 'pi-acp',
+    label: 'Pi',
+    description: 'Example custom ACP entry — build the binary from source, then edit the command.',
+    command: ['pi-acp'],
+    installUrl: 'https://agentclientprotocol.com/',
+  },
+];
+
+/**
+ * Build the PATCH body that registers a catalog entry: a single-id partial
+ * providers map with the custom-ACP override (extends:'acp' + label + command),
+ * enabled. Sent to PATCH /api/providers/config (then refreshProviders([id])).
+ */
+export function buildAcpProviderConfigPatch(entry: AcpCatalogEntry): ProviderConfigPatch {
+  return {
+    providers: {
+      [entry.id]: {
+        extends: 'acp',
+        label: entry.label,
+        description: entry.description,
+        command: entry.command,
+        enabled: true,
+      },
+    },
+  };
+}