feat(cli): add skill_lookup MCP for non-native agents (#1035)

* test: reproduce issue #752

* fix: expose skill lookup MCP tool (closes #752)

* test: cover ACP skill lookup instructions

* fix: inject ACP skill lookup instruction

* test: narrow skill lookup auto-approval

* fix: restrict skill lookup auto-approval

* test: cover exact skill lookup tool names

cli/src/opencode/opencodeLocalLauncher.ts

@@ -266,7 +266,9 @@ export async function opencodeLocalLauncher(
     let happyServer: { url: string; stop: () => void } | null = null;
     let opencodeConfigPath: string | null = null;
     try {
-        const bridge = await buildHapiMcpBridge(session.client);
+        const bridge = await buildHapiMcpBridge(session.client, {
+            skillLookup: { workingDirectory: session.path, flavor: 'opencode' }
+        });
         happyServer = bridge.server;
         logger.debug(`[opencode-local]: Started hapi MCP server at ${happyServer.url}`);
 

cli/src/opencode/opencodeRemoteLauncher.test.ts

@@ -178,6 +178,19 @@ describe('opencodeRemoteLauncher inline model switch', () => {
         harness.thoughtLevelOption = null;
     });
 
+    it('injects the skill lookup instruction only on the first prompt', async () => {
+        const { session } = createSessionStub([
+            { message: 'first', mode: createMode() },
+            { message: 'second', mode: createMode() }
+        ]);
+
+        await opencodeRemoteLauncher(session as never);
+
+        expect(JSON.stringify(harness.promptContents[0])).toContain('$name');
+        expect(JSON.stringify(harness.promptContents[0])).toContain('skill_lookup');
+        expect(JSON.stringify(harness.promptContents[1])).not.toContain('skill_lookup');
+    });
+
     it('calls setModel with opencode flavor between turns when the queued model differs', async () => {
         const { session } = createSessionStub([
             { message: 'first', mode: createMode('ollama/exaone:4.5-33b-q8') },

cli/src/opencode/opencodeRemoteLauncher.ts

@@ -55,7 +55,9 @@ class OpencodeRemoteLauncher extends RemoteLauncherBase {
         const session = this.session;
         const messageBuffer = this.messageBuffer;
 
-        const { server: happyServer, mcpServers } = await buildHapiMcpBridge(session.client);
+        const { server: happyServer, mcpServers } = await buildHapiMcpBridge(session.client, {
+            skillLookup: { workingDirectory: session.path, flavor: 'opencode' }
+        });
         this.happyServer = happyServer;
 
         const backend = createOpencodeBackend({

cli/src/opencode/utils/systemPrompt.test.ts

@@ -0,0 +1,30 @@
+import { afterEach, describe, expect, it } from 'vitest'
+import { mkdtemp, readFile, rm } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { ensureOpencodeConfig } from './opencodeConfig'
+import { TITLE_INSTRUCTION } from './systemPrompt'
+
+describe('OpenCode local HAPI instructions', () => {
+    let configDirectory: string | null = null
+
+    afterEach(async () => {
+        if (configDirectory) {
+            await rm(configDirectory, { recursive: true, force: true })
+            configDirectory = null
+        }
+    })
+
+    it('writes the skill lookup instruction into the configured system prompt', async () => {
+        configDirectory = await mkdtemp(join(tmpdir(), 'hapi-opencode-prompt-'))
+        const { instructionsPath } = ensureOpencodeConfig(
+            configDirectory,
+            { command: 'hapi', args: ['mcp'] },
+            TITLE_INSTRUCTION
+        )
+
+        const instructions = await readFile(instructionsPath, 'utf8')
+        expect(instructions).toContain('$name')
+        expect(instructions).toContain('skill_lookup')
+    })
+})

cli/src/opencode/utils/systemPrompt.ts

@@ -6,6 +6,7 @@
  */
 
 import { trimIdent } from '@/utils/trimIdent';
+import { SKILL_LOOKUP_INSTRUCTION } from '@/modules/common/skillLookupInstruction';
 
 /**
  * Title instruction for OpenCode to call the hapi MCP tool.
@@ -13,6 +14,7 @@ import { trimIdent } from '@/utils/trimIdent';
 export const TITLE_INSTRUCTION = trimIdent(`
     Use the title tool sparingly. For a new chat, call the tool "hapi_change_title" once after the user's initial request is clear, and set a concise task title. Do not rename the chat for routine progress, substeps, implementation details, or a slightly better wording. Rename only when the user's primary objective changes substantially and the existing title would be misleading.
     When you create or find a local image file that the user should see, call the tool "hapi_display_image" with the image path so HAPI can show it inline.
+    ${SKILL_LOOKUP_INSTRUCTION}
 `);
 
 /**