phase: 139_read_range_tool_lines

All verification is complete and green. Phase 139's three tasks (01–03) were already implemented in prior passes; this was the final verification pass, and every gate holds.

## Phase 139 — final verification report

**Verified in working tree (no code changes needed):**
- `readRangeSuffix` single-source-of-truth helper in `app.js` + byte-identical parity copy in `shared.js` (EN-dash ` (lines N–M)`, `(from line N)`, `(first N lines)`, `Number.isInteger(x) && x >= 1` guard mirroring the server's `_whole_line_number`)
- `appendToolLine(wrap, name, argument, offset = null, limit = null)` — `<span class="read-range">` sibling after `<code>`, only when suffix non-empty; `shared.js` `addToolLines` parity
- Live `tool` branch: guarded `ev.offset`/`ev.limit`, additive `toolAcc` records (non-range keeps pre-phase shape), status label carries the suffix (A2); restore path passes stored `t.offset`/`t.limit` through, phase-95 truncation note untouched
- E2E: `SAME_FILE_TRIGGER` mock flow (same file read twice, offsets 10/20 then 40/15) + 3-test Playwright suite

**Test / lint / coverage results:**
- `uv run pytest` (unit + integration): **3283 passed, 9 skipped, 0 failed**
- `uv run pytest --cov=app --cov-report=term-missing`: **TOTAL 99%** (>90% gate)
- `uv run pytest tests/e2e/test_read_range_tool_lines.py -v --no-cov`: **3 passed** in isolation
- `uv run ruff check .`: clean; `uv run pyright`: **0 errors, 0 warnings**

**Completion criteria:**
1. Range read renders `(lines N–M)` live; two same-file reads show DIFFERENT ranges — ✅ (E2E test 1)
2. Plain read byte-identical; phase-87/117 pins + emoji guard pass unedited — ✅ (E2E test 2 + full suite)
3. Suffix survives save → restore on chat page + shared page — ✅ (E2E test 3)
4. Full suite green, coverage >90%, E2E isolated green, ruff + pyright clean — ✅
5. Commit + phase move — left to the harness per executor rules (no `git add`/`commit` run)

**Notable:** the missing pytest summary line on one run was a transient output-buffering artifact, confirmed by re-run; DB was already up and healthy.

**Next pending phase:** `140_pictorial_pdf_pages`

app/schemas.py

@@ -978,6 +978,20 @@ class ToolCall(BaseModel):
     is JSON) — a saved chat written before phase 95 (no fields) validates
     UNCHANGED (the phase-50 backward-compat rule) and renders without
     the marker.
+
+    Phase 139 (task 02): the read's REQUESTED line range (phase 131's
+    ``offset`` / ``limit`` wire fields) rides the SAME record so a saved
+    chat re-renders the "(lines N–M)" suffix on the Reading line after
+    a save → restore round-trip (the chat page's restore path and the
+    shared page both read it off the stored row). Small additive fields
+    with defaults, no migration (the phase-95 truncated-fields
+    precedent): both are ABSENT (``None``) on every non-range record —
+    the UI includes a field only when well-formed — and both carry the
+    same >= 1 whole-line bound as the server's ``_whole_line_number``
+    (``app/api/chat.py``; the UI's guard mirrors it, so a value that
+    422s here is one the UI never legitimately produces). A saved chat
+    written before the phase (no fields) validates UNCHANGED and renders
+    without the suffix (the phase-50 backward-compat rule).
     """
 
     name: str = Field(max_length=100)
@@ -985,6 +999,8 @@ class ToolCall(BaseModel):
     truncated: bool = False
     chars_shown: int | None = Field(default=None, ge=0)
     chars_total: int | None = Field(default=None, ge=0)
+    offset: int | None = Field(default=None, ge=1)
+    limit: int | None = Field(default=None, ge=1)
 
 
 #: One suggestion chip (phase 83, A1): a short deterministic string —