refactor(src): narrow exception types in Phase 8 MEDIUM files (10 sites across 2 files)

Migrates the MEDIUM files (session_logger, warmup) by narrowing
the exception types from broad 'except Exception' to specific
stdlib exceptions.

session_logger.py (8 sites):
1. L99 - registry.register_session with print
   except Exception -> except (OSError, KeyError, AttributeError, TypeError)
2. L131 - registry.update_auto_whitelist_status with print
   except Exception -> except (OSError, KeyError, AttributeError, TypeError)
3. L147 - log_api_hook write/flush
   except Exception -> except (OSError, UnicodeEncodeError, ValueError)
4. L160 - log_comms json.dump
   except Exception -> except (OSError, TypeError, ValueError)
5. L188 - log_tool_call script file write
   except Exception -> except (OSError, UnicodeEncodeError)
6. L201 - log_tool_call write/flush
   except Exception -> except (OSError, UnicodeEncodeError, ValueError)
7. L226 - log_tool_output write_text
   except Exception -> except (OSError, UnicodeEncodeError)
8. L245 - log_cli_call write/flush
   except Exception -> except (OSError, TypeError, ValueError)

warmup.py (2 sites):
1. L276 - _log_canary sys.stderr.write
   except Exception -> except OSError
2. L300 - _log_summary sys.stderr.write
   except Exception -> except OSError

Decisions:
- warmup.py L85: raise RuntimeError (validation raise) - keep as-is per spec
- warmup.py L139, L215, L249: callback fires with except Exception - keep
  (user callbacks can throw anything; broad catch is correct)
- warmup.py L175: _warmup_one with except BaseException - keep
  (intentional broad catch for module import failures)

Tests verified:
- tests/test_session_logging.py (1 test) PASS
- tests/test_session_logger_reset.py (1 test) PASS
- tests/test_session_logger_optimization.py (4 tests) PASS
- tests/test_logging_e2e.py (1 test) PASS
- tests/test_warmup.py (10 tests) PASS
- tests/test_warmup_canaries.py (18 tests) PASS

src/session_logger.py

@@ -96,7 +96,7 @@ def open_session(label: Optional[str] = None) -> None:
 
   registry = LogRegistry(str(paths.get_logs_dir() / "log_registry.toml"))
   registry.register_session(_session_id, str(_session_dir), datetime.datetime.now())
- except Exception as e:
+ except (OSError, KeyError, AttributeError, TypeError) as e:
   print(f"Warning: Could not register session in LogRegistry: {e}")
 
  atexit.register(close_session)
@@ -128,7 +128,7 @@ def close_session() -> None:
 
   registry = LogRegistry(str(paths.get_logs_dir() / "log_registry.toml"))
   registry.update_auto_whitelist_status(_session_id)
- except Exception as e:
+ except (OSError, KeyError, AttributeError, TypeError) as e:
   print(f"Warning: Could not update auto-whitelist on close: {e}")
 
 def reset_session(label: Optional[str] = None) -> None:
@@ -144,7 +144,7 @@ def log_api_hook(method: str, path: str, payload: str) -> None:
  try:
   _api_fh.write(f"[{ts_entry}] {method} {path} - Payload: {payload}\n")
   _api_fh.flush()
- except Exception:
+ except (OSError, UnicodeEncodeError, ValueError):
   pass
 
 def log_comms(entry: dict[str, Any]) -> None:
@@ -157,7 +157,7 @@ def log_comms(entry: dict[str, Any]) -> None:
   return
  try:
   _comms_fh.write(json.dumps(entry, ensure_ascii=False, default=str) + "\n")
- except Exception:
+ except (OSError, TypeError, ValueError):
   pass
 
 def log_tool_call(script: str, result: str, script_path: Optional[str]) -> Optional[str]:
@@ -185,7 +185,7 @@ def log_tool_call(script: str, result: str, script_path: Optional[str]) -> Optio
  try:
   if ps1_path:
    ps1_path.write_text(script, encoding="utf-8")
- except Exception as exc:
+ except (OSError, UnicodeEncodeError) as exc:
   ps1_path = None
   ps1_name = f"(write error: {exc})"
 
@@ -198,7 +198,7 @@ def log_tool_call(script: str, result: str, script_path: Optional[str]) -> Optio
    f"---\n\n"
   )
   _tool_fh.flush()
- except Exception:
+ except (OSError, UnicodeEncodeError, ValueError):
   pass
 
  return str(ps1_path) if ps1_path else None
@@ -223,7 +223,7 @@ def log_tool_output(content: str) -> Optional[str]:
  try:
   out_path.write_text(content, encoding="utf-8")
   return str(out_path)
- except Exception:
+ except (OSError, UnicodeEncodeError):
   return None
 
 def log_cli_call(command: str, stdin_content: Optional[str], stdout_content: Optional[str], stderr_content: Optional[str], latency: float) -> None:
@@ -242,5 +242,5 @@ def log_cli_call(command: str, stdin_content: Optional[str], stdout_content: Opt
   }
   _cli_fh.write(json.dumps(log_data, ensure_ascii=False, default=str) + "\n")
   _cli_fh.flush()
- except Exception:
+ except (OSError, TypeError, ValueError):
   pass

src/warmup.py

@@ -273,7 +273,7 @@ class WarmupManager:
    try:
     sys.stderr.write(line)
     sys.stderr.flush()
-   except Exception: pass
+   except OSError: pass
 
  def _log_summary(self) -> None:
   if not self._log_to_stderr: return
@@ -292,12 +292,12 @@ class WarmupManager:
   if failed: parts.append(f"{failed} failed")
   if cancelled: parts.append(f"{cancelled} cancelled")
   with self._log_lock:
-   try:
-    sys.stderr.write(f"[warmup done] {total} modules: {', '.join(parts)} (sum of per-module elapsed: {total_ms:.1f}ms)\n")
-    if main_thread_violations:
-     sys.stderr.write(f"[warmup WARNING] {len(main_thread_violations)} module(s) loaded on the MAIN THREAD (violates main thread purity invariant): {', '.join(main_thread_violations)}\n")
-    sys.stderr.flush()
-   except Exception: pass
+    try:
+     sys.stderr.write(f"[warmup done] {total} modules: {', '.join(parts)} (sum of per-module elapsed: {total_ms:.1f}ms)\n")
+     if main_thread_violations:
+      sys.stderr.write(f"[warmup WARNING] {len(main_thread_violations)} module(s) loaded on the MAIN THREAD (violates main thread purity invariant): {', '.join(main_thread_violations)}\n")
+     sys.stderr.flush()
+    except OSError: pass
 
  def _snapshot(self) -> dict[str, list[str]]:
   return {