fix(learn): pass explicit model in tests to avoid API key requirement

SessionAnalyzer() without a model calls _detect_default_model() which
raises when no API keys are set (e.g., in CI). Pass model="test-model"
in the three tests that mock _call_llm.

headroom/learn/analyzer.py

@@ -62,9 +62,7 @@ class SessionAnalyzer:
     def __init__(self, model: str | None = None):
         self.model = model
 
-    def analyze(
-        self, project: ProjectInfo, sessions: list[SessionData]
-    ) -> AnalysisResult:
+    def analyze(self, project: ProjectInfo, sessions: list[SessionData]) -> AnalysisResult:
         """Analyze sessions and produce recommendations via LLM."""
         all_calls = [tc for s in sessions for tc in s.tool_calls]
         failed_calls = [tc for tc in all_calls if tc.is_error]
@@ -134,7 +132,9 @@ def _build_digest(project: ProjectInfo, sessions: list[SessionData]) -> str:
 
     for session in sessions:
         if chars_used > char_budget:
-            lines.append(f"... (remaining {len(sessions) - sessions.index(session)} sessions truncated)")
+            lines.append(
+                f"... (remaining {len(sessions) - sessions.index(session)} sessions truncated)"
+            )
             break
 
         session_header = (
@@ -179,7 +179,7 @@ def _format_event(event: SessionEvent) -> str | None:
 
     if event.type == "user_message" and event.text.strip():
         text = event.text.strip()[:300]
-        return f"  [{event.msg_index}] USER: \"{text}\""
+        return f'  [{event.msg_index}] USER: "{text}"'
 
     if event.type == "interruption":
         return f"  [{event.msg_index}] INTERRUPTED: {event.text[:150]}"
@@ -188,7 +188,7 @@ def _format_event(event: SessionEvent) -> str | None:
         return (
             f"  [{event.msg_index}] SUBAGENT: {event.agent_tool_count} tool calls, "
             f"{event.agent_tokens:,} tokens, {event.agent_duration_ms / 1000:.1f}s "
-            f"— prompt: \"{event.agent_prompt[:100]}\""
+            f'— prompt: "{event.agent_prompt[:100]}"'
         )
 
     return None
@@ -384,7 +384,5 @@ class FailureAnalyzer:
     def __init__(self) -> None:
         self._analyzer = SessionAnalyzer()
 
-    def analyze(
-        self, project: ProjectInfo, sessions: list[SessionData]
-    ) -> AnalysisResult:
+    def analyze(self, project: ProjectInfo, sessions: list[SessionData]) -> AnalysisResult:
         return self._analyzer.analyze(project, sessions)

headroom/learn/scanner.py

@@ -240,9 +240,7 @@ class ClaudeCodeScanner(ConversationScanner):
                         total_input_tokens += usage.get("cache_creation_input_tokens", 0)
                         total_output_tokens += usage.get("output_tokens", 0)
                     elif line_type == "user":
-                        self._extract_tool_results(
-                            d, tool_uses, tool_calls, events, msg_index, ts
-                        )
+                        self._extract_tool_results(d, tool_uses, tool_calls, events, msg_index, ts)
                         self._extract_user_events(d, events, msg_index, ts)
 
         except (OSError, UnicodeDecodeError) as e:
@@ -251,12 +249,8 @@ class ClaudeCodeScanner(ConversationScanner):
 
         # Also wrap tool_calls as events for unified access
         for tc in tool_calls:
-            if not any(
-                e.type == "tool_call" and e.tool_call is tc for e in events
-            ):
-                events.append(
-                    SessionEvent(type="tool_call", msg_index=tc.msg_index, tool_call=tc)
-                )
+            if not any(e.type == "tool_call" and e.tool_call is tc for e in events):
+                events.append(SessionEvent(type="tool_call", msg_index=tc.msg_index, tool_call=tc))
         events.sort(key=lambda e: e.msg_index)
 
         return SessionData(
@@ -332,7 +326,9 @@ class ClaudeCodeScanner(ConversationScanner):
             )
             tool_calls.append(tc)
             events.append(
-                SessionEvent(type="tool_call", msg_index=msg_index, timestamp=timestamp, tool_call=tc)
+                SessionEvent(
+                    type="tool_call", msg_index=msg_index, timestamp=timestamp, tool_call=tc
+                )
             )
 
             # Extract subagent summary from toolUseResult metadata

tests/test_learn/test_analyzer.py

@@ -261,7 +261,7 @@ class TestSessionAnalyzer:
             "memory_file_rules": [],
         }
 
-        analyzer = SessionAnalyzer()
+        analyzer = SessionAnalyzer(model="test-model")
         sessions = [
             SessionData(
                 session_id="s1",
@@ -283,7 +283,7 @@ class TestSessionAnalyzer:
     def test_handles_llm_failure_gracefully(self, mock_call_llm: MagicMock):
         mock_call_llm.side_effect = RuntimeError("API key not set")
 
-        analyzer = SessionAnalyzer()
+        analyzer = SessionAnalyzer(model="test-model")
         sessions = [
             SessionData(
                 session_id="s1",
@@ -309,7 +309,7 @@ class TestSessionAnalyzer:
         ]
         sessions = [SessionData(session_id="s1", tool_calls=[tc], events=events)]
 
-        analyzer = SessionAnalyzer()
+        analyzer = SessionAnalyzer(model="test-model")
         analyzer.analyze(_project(), sessions)
 
         # Check that the digest passed to the LLM includes user message