feat(cli): ping-peer CLI + MCP ping_peer for peer messaging (#1195)

* feat(cli): add ping-peer CLI and MCP ping_peer for peer messaging

Promote resume-if-inactive + wait-active + POST message into a first-class
CLI command and session MCP tool so agents stop reinventing JWT+curl.

Fixes #1194

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(cli): do not auto-approve MCP ping_peer

Cross-session messaging can resume a peer and inject a prompt, so keep
permission-mode gating (Codex PR review Major on #1195).

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(cli): require approval for ping_peer in read-only mode

Read-only auto-approve treated non-write names as safe; ping_peer can still
resume a peer and inject prompts, so gate it like a write tool.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(cli): keep ping_peer out of Claude --allowedTools

toolNames still registers the MCP tool, but Claude auto-allow must not
pre-approve cross-session resume+inject without a permission prompt.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(cli): re-check session active before ping-peer send

List/get can race; POST /messages still 409s if the target flips inactive
before send. Resume+wait again (and re-gate pi) immediately before POST.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

cli/src/codex/utils/buildHapiMcpBridge.test.ts

@@ -14,8 +14,8 @@ vi.mock('@/claude/utils/startHappyServer', () => ({
         return {
             url: 'http://127.0.0.1:43006/',
             toolNames: options.skillLookup
-                ? ['change_title', 'display_image', 'skill_lookup']
-                : ['change_title', 'display_image'],
+                ? ['change_title', 'display_image', 'ping_peer', 'skill_lookup']
+                : ['change_title', 'display_image', 'ping_peer'],
             stop: vi.fn()
         }
     })
@@ -71,7 +71,7 @@ describe('buildHapiMcpBridge skill lookup config', () => {
             '--url',
             'http://127.0.0.1:43006/',
             '--tools',
-            'change_title,display_image,skill_lookup'
+            'change_title,display_image,ping_peer,skill_lookup'
         ])
         expect(bridge.mcpServers.hapi.tools).toEqual({
             change_title: { approval_mode: 'approve' },
@@ -82,7 +82,7 @@ describe('buildHapiMcpBridge skill lookup config', () => {
     it('does not expose skill_lookup for native-skill bridge callers', async () => {
         const bridge = await buildHapiMcpBridge(createClient())
 
-        expect(harness.cliArgs.at(-1)).toBe('change_title,display_image')
+        expect(harness.cliArgs.at(-1)).toBe('change_title,display_image,ping_peer')
         expect(bridge.mcpServers.hapi.tools).toEqual({
             change_title: { approval_mode: 'approve' }
         })

cli/src/codex/utils/buildHapiMcpBridge.ts

@@ -95,6 +95,8 @@ export async function buildHapiMcpBridge(
             approval_mode: 'approve'
         };
     }
+    // ping_peer is registered on the HTTP MCP server / stdio bridge, but is not
+    // auto-approved: it targets another session (resume + inject message).
     if (options.skillLookup) {
         tools.skill_lookup = {
             approval_mode: 'approve'

cli/src/codex/utils/systemPrompt.ts

@@ -19,6 +19,7 @@ export const TITLE_INSTRUCTION = trimIdent(`
     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 functions.hapi__display_image with the image path. If that exact tool name is unavailable, use an equivalent alias such as hapi__display_image, mcp__hapi__display_image, or hapi_display_image.
+    To message another HAPI session (peer handoff / nudge), call functions.hapi__ping_peer with sessionIdPrefix and message - do not reinvent JWT+curl. Shell fallback: hapi ping-peer <prefix> <message>.
 `);
 
 /**