fix: auto-install bridge dependencies when connecting Claude Max

Instead of showing an error when the Claude Agent SDK is missing,
automatically install bun and run bun install in the bridge directory.
This removes the manual setup step for new users connecting their
Claude Max subscription.

Author: EightRice

atn/runtime/provider_manager.py

@@ -556,12 +556,13 @@ async def configure_provider(self, provider_id: str, api_key: str = "") -> dict[
             return {"status": "ok", "provider": provider_id, "models": models}
 
         elif info["auth_type"] == "bridge":
+            # Auto-install bridge dependencies if missing
+            await self._ensure_bridge_deps()
             auth = await self._check_claude_auth()
             if not auth["installed"]:
                 raise ValueError(
-                    "Claude Code SDK not found. Install Claude Code "
-                    "(https://claude.ai/download) and run 'bun install' "
-                    "in the bridge/ directory."
+                    "Bridge setup failed. Ensure 'bun' is installed "
+                    "(npm i -g bun) and try again."
                 )
             if not auth["logged_in"]:
                 log.info("Claude Code not authenticated — launching browser login")
@@ -853,6 +854,63 @@ async def _validate_api_key(self, provider_id: str, api_key: str) -> None:
         except httpx.TimeoutException:
             raise ValueError(f"Timeout connecting to {provider_id} API")
 
+    async def _ensure_bridge_deps(self) -> None:
+        """Auto-install bridge dependencies (bun install) if missing."""
+        bridge_dir = Path(__file__).resolve().parent.parent.parent / "bridge"
+        pkg_json = bridge_dir / "package.json"
+        node_modules = bridge_dir / "node_modules"
+        cli_js = node_modules / "@anthropic-ai" / "claude-agent-sdk" / "cli.js"
+
+        if cli_js.exists():
+            return  # Already installed
+
+        if not pkg_json.exists():
+            log.warning("Bridge package.json not found at %s", bridge_dir)
+            return
+
+        # Check bun is available
+        import shutil
+        bun = shutil.which("bun")
+        if not bun:
+            # Try installing bun via npm
+            npm = shutil.which("npm")
+            if npm:
+                log.info("Installing bun via npm...")
+                try:
+                    proc = await asyncio.create_subprocess_exec(
+                        npm, "install", "-g", "bun",
+                        stdout=asyncio.subprocess.PIPE,
+                        stderr=asyncio.subprocess.PIPE,
+                    )
+                    await asyncio.wait_for(proc.communicate(), timeout=120)
+                    bun = shutil.which("bun")
+                except Exception as e:
+                    log.warning("Failed to install bun: %s", e)
+
+        if not bun:
+            log.warning("bun not found — cannot auto-install bridge dependencies")
+            return
+
+        # Run bun install in the bridge directory
+        log.info("Installing bridge dependencies in %s ...", bridge_dir)
+        try:
+            proc = await asyncio.create_subprocess_exec(
+                bun, "install",
+                cwd=str(bridge_dir),
+                stdout=asyncio.subprocess.PIPE,
+                stderr=asyncio.subprocess.PIPE,
+            )
+            stdout, stderr = await asyncio.wait_for(proc.communicate(), timeout=120)
+            if proc.returncode == 0:
+                log.info("Bridge dependencies installed successfully")
+            else:
+                log.warning("bun install failed (exit %s): %s",
+                            proc.returncode, stderr.decode(errors="replace")[:500])
+        except asyncio.TimeoutError:
+            log.warning("bun install timed out")
+        except Exception as e:
+            log.warning("Failed to install bridge dependencies: %s", e)
+
     def _resolve_sdk_cli(self) -> Path | None:
         bridge_dir = Path(__file__).resolve().parent.parent.parent / "bridge"
         cli_js = bridge_dir / "node_modules" / "@anthropic-ai" / "claude-agent-sdk" / "cli.js"