workspace: record try/except/else refactor in _read_agent_stream

Co-authored-by: Ralphify <noreply@ralphify.co>

Author: 2 people

workspace/ralphs/improve-codebase/coverage/_agent.md

@@ -1,9 +1,21 @@
 # `_agent.py` coverage
 
-Valid at: d8d5592
+Valid at: cf72fd9
 
 ## Recent changes
 
+- cf72fd9 — replaced the `parsed = None` sentinel in `_read_agent_stream`
+  with a `try/except/else` block.  The old code set `parsed = None` in
+  the JSON-decode-except branch solely so the next line's
+  `if isinstance(parsed, dict):` would fall through; restructuring with
+  `try: ... except: pass; else: if isinstance(...):` makes the "only
+  forward when parsing succeeded" intent structural instead of encoded
+  through a sentinel value.  The error path now skips the isinstance
+  check entirely (dead work before), and the success path is unchanged.
+  `parsed` is no longer bound when the except clause runs, which matches
+  Python convention — the value was always meant to be ignored there.
+  Pinned by `tests/test_agent.py::test_ignores_non_json_lines` and the
+  broader stream-JSON coverage in that file.
 - d8d5592 — gated the `"".join(...)` of `stream.stdout_lines` and
   `stderr_lines` at the tail of `_run_agent_streaming` on
   `log_dir is not None`.  The joined strings were only consumed by

workspace/ralphs/improve-codebase/iterations.md

@@ -2,6 +2,8 @@
 
 One line per iteration: `<sha> <summary>`.
 
+cf72fd9 refactor: replace `parsed = None` sentinel with try/except/else in `_read_agent_stream` — the sentinel only existed so that `isinstance(parsed, dict)` on the next line would fall through on JSON-parse failure.  Moving the dict-handling into the try/else branch expresses "only run when parse succeeded" structurally and drops both the sentinel assignment and the redundant isinstance check on the error path.  Behavior preserved — valid-but-non-dict JSON (lists, numbers, strings) still skips forwarding via the inner isinstance guard.  Same sentinel→structure shape as prior Phase 4 scope narrowings, applied one level up.
+
 a6f4c47 refactor: drop redundant BOM-startswith guard before `removeprefix` in `parse_frontmatter` — `str.removeprefix` already returns the string unchanged when the prefix is absent, so the `if text.startswith(_UTF8_BOM):` wrapper was dead defensive code.  Behavior preserved — `test_utf8_bom_does_not_break_frontmatter` still pins the BOM-stripping path and every other test exercises the no-BOM path.  Same "drop the guard when the operation already handles the no-match case" shape as 5337d88 (empty dict → `" · ".join([])`), 4ccfa9a (empty list → `" · ".join([])`), and 8cb0d47 (redundant `max(..., 1)` floor).
 
 3a8908d refactor: use `next(reversed(...), None)` in `enter_fullscreen` history fallback — the compound `if initial_id is None and self._iteration_history:` guard mixed two concerns (only fall back when nothing is live, *and* avoid `next(reversed({}))` raising StopIteration).  Switching to the `next(it, default)` sentinel idiom lets the standard default handle empty-dict case so the outer `if` only encodes the "fall back when nothing live" intent.  Behavior preserved — the existing `if initial_id is None or panel_for(...) is None:` next branch still prints "no iterations yet" and returns False, covered by `test_enter_without_iteration_prints_hint`.