# Story: Whole-Document Context — a matched document is never truncated

**Phase:** `24_whole_document_context` · **E2E:** `tests/e2e/test_whole_document_context.py`

## Bug report (TODO.md L3–L4, verbatim)

> *"Documents are truncated for some reason? This should never happen"*
>
> *"When the LLM matches a chunk it should get the entire document placed in its context so it can see the whole thing before answering the question"*

## Narrative

As **a user asking about an indexed note**, I want **the entire document
in the LLM's context** whenever retrieval matches one of its chunks — so
the answer is grounded in the whole note, not a silently cut-down version
of it.

- **Given** a question whose chunk matches a document
- **When** the turn assembles context
- **Then** the LLM receives the **entire** parent document — never a
  `[…truncated…]`-cut version — so the answer is grounded in the whole
  note.

## Owner-confirmed (2026-08-24, roadmap D1–D5)
1. **D1 — no cap at all (revises LOCKED A7):** `select_documents` returns
   the full top-N document texts, always. The `max_context_chars` setting
   and `BOR_MAX_CONTEXT_CHARS` env var are removed. If a future KB ever
   makes the prompt too large for the model, the existing `LLMError` → SSE
   `error` path surfaces it loudly — no silent partial context. The
   emergency-valve variant (raised cap + warning log) was **explicitly
   rejected**.
2. **D2 — `top_n_docs = 2` unchanged** (the TODO is about truncation, not
   about how many documents).
3. **D3 — no viewer/import changes** — both already serve full content
   (verified diagnosis above).
4. **D4 — E2E evidence via a deterministic mock tail-echo** (repo pattern,
   cf. the phase-15 tuning-note echo); the big documents are seeded
   directly in the DB inside the E2E test — `tests/fixtures/docs/` must
   not grow, because other suites pin `summary.added == 8`.
5. **D5 — no `query_log` schema change** (no new columns, no migration).

## Acceptance criteria
1. No budget parameter in `select_documents` — it never truncates
   (`TRUNCATION_MARKER` remains for the steering section only).
2. `BOR_MAX_CONTEXT_CHARS` gone from settings/env/README
   (`app/config.py`, `.env.example`, `README.md`).
3. The story E2E's three tests green in isolation
   (`uv run pytest tests/e2e/test_whole_document_context.py -v --no-cov`).
4. Steering-note truncation (phase 15, `BOR_STEERING_MAX_CHARS` + shared
   marker) unchanged.
5. Unit + integration green, `app/` coverage >90%, one
   `--no-gpg-sign` commit.

## Playwright Mapping Rule
**Test Scenario → `tests/e2e/test_whole_document_context.py`** (mock LLM
tail-echo, oversized documents seeded directly in the DB):
1. `test_whole_document_over_old_cap_reaches_llm` — a 30 000-char document
   (past the old 24 000 cap): its tail sentinel (last line) is echoed in
   the rendered answer, `[…truncated…]` is absent, the source chip renders,
   `query_log` row `deflected == False`.
2. `test_second_document_of_over_cap_pair_reaches_llm` — two ~16 000-char
   documents (32 000 combined — the exact case the old budget cut): the
   second, lower-ranked document's tail sentinel is echoed (doc 1's is not
   — it pins the rank order), both source chips render.
3. `test_small_document_path_unchanged` — regression: standard fixtures via
   the real importer → grounded answer with the `kubernetes.md` chip, no
   `[…truncated…]` (the under-cap path is byte-identical to before).