fix(mcp): wrap _fetch calls in try/except per graceful HTTP error handling

Ogni tool MCP ora cattura requests.HTTPError e restituisce una stringa
di errore contestuale invece di crashare. Aggiunti 3 test per i casi
403, 404, 500 su session_bootstrap, workspace_triage e topic_index.

Author: Gabrymi93

src/agent_context_builder/mcp_server.py

@@ -125,19 +125,28 @@ def _fetch(path: str) -> str:
 @mcp.tool()
 def session_bootstrap() -> str:
     """Orientamento rapido: repo attivi, PR aperte, discussion, stato locale, topic."""
-    return _fetch("session_bootstrap.md")
+    try:
+        return _fetch("session_bootstrap.md")
+    except requests.HTTPError as e:
+        return f"session_bootstrap: {e}"
 
 
 @mcp.tool()
 def workspace_triage() -> str:
     """Triage machine-readable: PR, issue, discussion, stato git per repo, warning."""
-    return _fetch("workspace_triage.json")
+    try:
+        return _fetch("workspace_triage.json")
+    except requests.HTTPError as e:
+        return f"workspace_triage: {e}"
 
 
 @mcp.tool()
 def topic_index() -> str:
     """Topic index v2 — repos, datasets_by_source, operational_topics."""
-    return _fetch("topic_index.json")
+    try:
+        return _fetch("topic_index.json")
+    except requests.HTTPError as e:
+        return f"topic_index: {e}"
 
 
 @mcp.tool()

tests/test_mcp_server.py

@@ -1,5 +1,6 @@
 """Tests for MCP server resources and tools."""
 
+import requests
 from unittest.mock import MagicMock, patch
 
 
@@ -143,3 +144,47 @@ def test_refresh_context_api_error(monkeypatch):
         result = refresh_context()
 
     assert "403" in result
+
+
+def _mock_http_error(status: int):
+    """Return a mock raising HTTPError."""
+    response = _mock_response("error", status=status)
+    exc = requests.HTTPError(f"{status} Client Error", response=response)
+    response.raise_for_status.side_effect = exc
+    return response
+
+
+def test_session_bootstrap_http_error(monkeypatch):
+    """session_bootstrap returns error string on HTTP failure instead of raising."""
+    from agent_context_builder.mcp_server import session_bootstrap
+
+    with patch("agent_context_builder.mcp_server.requests.get") as mock_get:
+        mock_get.return_value = _mock_http_error(403)
+        result = session_bootstrap()
+
+    assert "session_bootstrap" in result
+    assert "403" in result
+
+
+def test_workspace_triage_http_error(monkeypatch):
+    """workspace_triage returns error string on HTTP failure instead of raising."""
+    from agent_context_builder.mcp_server import workspace_triage
+
+    with patch("agent_context_builder.mcp_server.requests.get") as mock_get:
+        mock_get.return_value = _mock_http_error(404)
+        result = workspace_triage()
+
+    assert "workspace_triage" in result
+    assert "404" in result
+
+
+def test_topic_index_http_error(monkeypatch):
+    """topic_index returns error string on HTTP failure instead of raising."""
+    from agent_context_builder.mcp_server import topic_index
+
+    with patch("agent_context_builder.mcp_server.requests.get") as mock_get:
+        mock_get.return_value = _mock_http_error(500)
+        result = topic_index()
+
+    assert "topic_index" in result
+    assert "500" in result