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/unit/test_shared_page.py

@@ -19,8 +19,8 @@ silent regression is caught without a browser:
   chat page's interactive builders, and the rendered messages contain
   no button/form/link — the chips are plain spans, the source chips
   carry no ``href``;
-* the shared shell's reading-column mapping (--chat-column token,
-  phase 58) + the static-chip and
+* the shared shell's reading-column mapping (--chat-column token —
+  the 72rem container width, phase 100) + the static-chip and
   invalid-state CSS (the ≤640px squeeze included).
 """
 from __future__ import annotations
@@ -384,17 +384,18 @@ def test_brand_note_resolves_at_call_time() -> None:
 
 
 def test_shared_shell_maps_to_the_reading_column() -> None:
-    """The PLAN §7 column contract (phase 58): .shared-shell is the
-    centered chat column riding the --chat-column token (46rem base,
-    92rem at >=1500px wide desktops — owner instruction 2026-08-31,
-    TODO L5 / D2). The conversation reads exactly like the chat
-    page's, so the existing .msg/.bubble CSS applies unchanged."""
+    """The 72rem-everywhere contract (phase 100, owner instruction
+    2026-09-12): .shared-shell is the centered chat column riding the
+    --chat-column token — equal to the .container's cap, so the shared
+    page reads at the RAG page's width. The conversation reads exactly
+    like the chat page's, so the existing .msg/.bubble CSS applies
+    unchanged."""
     css = _css()
     block = re.search(r"\.shared-shell \{([\s\S]*?)\n\}", css)
     assert block, "styles.css must style .shared-shell"
     body = block.group(1)
     assert "max-width: var(--chat-column)" in body, (
-        "the PLAN §7 centered chat column (phase 58 token)"
+        "the centered chat column riding the token (the 72rem width)"
     )
     assert "46rem" not in body.split("/*")[0], (
         "no hard-coded cap — the width rides the token"