phase: 100_page_width_consistency

**Phase 100 — final verification pass: all green.**

- Verified the shipped CSS contract directly: `--chat-column: 72rem` in `:root`; 0 literal `max-width: 46rem`; no `@media (min-width: 1500px)` block; exactly 4 token-capped reading columns; tuning/theme/doc-edit shells cap-free, structurally `.sources-shell`; `mock_llm.py` diff is comment-only.
- Defect found & fixed (phase-93 suite): `test_theme_semantic_completion.py::test_reset_removes_tag_byte_identical` raced theme.js's post-PUT refetch — it asserted the `#bor-theme` tag was gone right after the result line, but tag removal lands in the reconcile after the re-fetch (failed ~1 in 5 runs after `test_chat_rag`, reproduced). Fixed with an auto-waiting `expect(...).to_have_count(0)` (settled-state wait, the file's existing house pattern). 6/6 clean on the repro loop after.
- Tests/lint/coverage: `uv run pytest --cov=app --cov-report=term-missing` → 2052 passed, **99%** on `app/`; `uv run ruff check .` + `uv run pyright` → 0 errors.
- E2E in isolation (all passed): `test_wide_desktop_column.py` 3 (the phase suite — chat==tuning==theme==RAG ±4px at 1280 & 1920, ≈1152px; shared ≈1152px; standalone doc ≈1112px; modal unchanged ≈1100px; 360px overflow-free), `test_ui_customization` 4, `test_admin_theme_tab` 5, `test_document_viewer` 7, `test_save_share_ux` 5, `test_sticky_navbar` 3, `test_markdown_tables` 6, `test_responsive_polish` 7, `test_chat_rag` 3, `test_theme_semantic_completion` 8.
- Completion criteria: ① measured 72rem everywhere (≥~1200px, ±4px) + full-width below + 360px clean — **PASS** (E2E); ② zero 46rem rules / no 1500px block / four token selectors — **PASS** (grep + unit pins); ③ B4 byte-identical no-op + mobile squeeze — **PASS** (theme + responsive suites green); ④ full suite / coverage / lint — **PASS**; ⑤ atomic commit — left to the harness per executor protocol (all changes in the working tree, uncommitted).
- Deviations: none from phase decisions; only change in this pass is the race fix above (test-only, behavior unchanged).
- Next pending phase: `98_sync_summary_visibility` (numeric order in `todo/`; also pending: 99, 101–105).

tests/e2e/mock_llm.py

@@ -327,7 +327,8 @@ Implements just enough of the aipi surface:
     a deliberately wide 5-column table — byte-stable, so the story E2E
     can assert the rendered ``<table class="md-table">`` shape, the
     escaped XSS line, and the wrapper's horizontal scroll inside the
-    46rem column. Checked BEFORE the ``DEFLECT_MODE`` branch (a
+    72rem container column (phase 100). Checked BEFORE the
+    ``DEFLECT_MODE`` branch (a
     deflection prompt never carries the marker, same reasoning as
     ``SUMMARY_MODE``), so a marker question always gets the table
     answer; the E2E asks it against an on-topic fixture (HIGH gate) and
@@ -584,7 +585,8 @@ TABLE_TRIGGER = "show me a table"
 #: The fixed table answer (phase 44) — byte-stable on purpose: the story
 #: E2E asserts the rendered table shape, the escaped ``<img onerror>``
 #: line (the XSS payload must survive the mock byte-for-byte), and the
-#: wide table's ``scrollWidth > clientWidth`` inside the 46rem column.
+#: wide table's ``scrollWidth > clientWidth`` inside the 72rem container
+#: column (phase 100).
 #: Phase 74 (chat history, TODO L4): a user message containing this
 #: substring (case-insensitive) gets the deterministic HISTORY ECHO
 #: (``_history_echo`` below — see the module docstring): the prior-turn
@@ -1653,7 +1655,8 @@ def compose_answer(body: dict[str, Any]) -> str:
         # <img onerror> XSS probe line (it must survive the mock
         # byte-for-byte so the E2E can prove the renderer neutralizes
         # it), and a wide 5-column table (guarantees scrollWidth >
-        # clientWidth inside the 46rem column). Byte-stable. Checked
+        # clientWidth inside the 72rem container column, phase 100).
+        # Byte-stable. Checked
         # BEFORE the DEFLECT_MODE branch: a deflection prompt never
         # carries the marker (it lives in the user message, same
         # reasoning as SUMMARY_MODE), so a marker question always gets