fix(session_peek): scan full file when size ≤10KB

Author: clean6378-max-it

docs/architecture.md

@@ -75,9 +75,9 @@ In `utils/tool_dispatch.py`, tool results are classified through `_parse_tool_re
 
 When adding a new tool renderer:
 
-1. Add predicate + builder pair in the dispatch table in the correct order (specific before generic).
-2. Add or extend a JSONL fixture under `tests/fixtures/` if needed.
-3. Run `pytest tests/test_jsonl_parser.py -v`.
+1. Add a `(predicate, builder)` pair to `_TOOL_RESULT_DISPATCH` in `utils/tool_dispatch.py`, preserving existing predicate order unless you also update fixtures and ordering tests (`tests/test_jsonl_parser.py`, `tests/test_real_session_fixtures.py`). Order is **not** “specific before generic” in general — the first match wins. `_tool_result_pred_task_message` is the intentional broad-before-narrow exception (`task_id` or `message` before retrieval/completed/async).
+2. Add or extend a JSONL fixture under `tests/fixtures/` (especially for overlaps with existing predicates).
+3. Run `pytest tests/test_jsonl_parser.py tests/test_real_session_fixtures.py -v`.
 
 ## Export state machine
 

utils/session_peek.py

@@ -6,6 +6,9 @@
 from models.session import QuickSessionInfoDict
 from utils.jsonl_helpers import entry_message, extract_text, strip_system_tags
 
+_TAIL_READ_MIN_BYTES = 10 * 1024
+_MAX_HEAD_LINES = 80
+
 
 def quick_session_info(filepath: str) -> QuickSessionInfoDict:
     """Lightweight peek at a session file -- returns title and last_timestamp
@@ -17,13 +20,15 @@ def quick_session_info(filepath: str) -> QuickSessionInfoDict:
     title = None
     first_ts = None
     last_ts = None
+    file_size = os.path.getsize(filepath)
 
     # --- Pass 1: read first lines to find the title and first_timestamp ---
     with open(filepath, "r", encoding="utf-8", errors="replace") as f:
         lines_read = 0
         for line in f:
             lines_read += 1
-            if lines_read > 80:
+            # Large files use pass-2 tail read for last_timestamp; cap head scan only then.
+            if file_size > _TAIL_READ_MIN_BYTES and lines_read > _MAX_HEAD_LINES:
                 break
             line = line.strip()
             if not line:
@@ -49,8 +54,7 @@ def quick_session_info(filepath: str) -> QuickSessionInfoDict:
                         title = first_line
 
     # --- Pass 2: read last chunk for the last timestamp ---
-    file_size = os.path.getsize(filepath)
-    if file_size > 10000:
+    if file_size > _TAIL_READ_MIN_BYTES:
         # Only bother with tail-read for non-tiny files
         chunk_size = min(file_size, 32768)
         with open(filepath, "rb") as f: