diff --git a/jobs/documents-ingest/pyproject.toml b/jobs/documents-ingest/pyproject.toml
index 9cead27..b930283 100644
--- a/jobs/documents-ingest/pyproject.toml
+++ b/jobs/documents-ingest/pyproject.toml
@@ -11,12 +11,15 @@ dependencies = [
     "structlog>=24.1",
     "aiohttp>=3.9",
     "kb-mail",
+    "PyYAML>=6.0",
+    "anthropic>=0.40",
 ]
 
 [project.scripts]
 documents-ingest = "documents_ingest.extractor:main"
 documents-ingest-paperless = "documents_ingest.paperless_adapter:main"
 documents-ingest-embed = "documents_ingest.chunk_embed:main"
+documents-ingest-summarize = "documents_ingest.summarize:main"
 
 [tool.setuptools.packages.find]
 where = ["src"]
diff --git a/jobs/documents-ingest/src/documents_ingest/summarize.py b/jobs/documents-ingest/src/documents_ingest/summarize.py
new file mode 100644
index 0000000..f41530c
--- /dev/null
+++ b/jobs/documents-ingest/src/documents_ingest/summarize.py
@@ -0,0 +1,675 @@
+"""Summarize + tag job — module 5 phase 3, plan step 3 (docs/kb/modules/05-faza3-plan.md,
+§5 step 3, §2 decision 3: two-track A/B pilot).
+
+Pipeline: `document_chunk.text WHERE excluded_reason IS NULL ORDER BY chunk_index` per
+`source='paperless'` envelope (duplicates via `entities[type=duplicate_of]` skipped whole)
+-> LLM (`--backend ollama|anthropic`) forced-JSON `{"summary": ..., "tags": [...]}`
+-> `INSERT document_summary` (`services/kb-postgres/init/004_summaries.sql`). `envelope` and
+`document_chunk` are read-only here; this job only ever `INSERT`s into `document_summary`.
+
+Two backends write the same table under different `model` values — `UNIQUE (envelope_id,
+model)` exists precisely so both A/B tracks coexist (plan §2 decision 3). A second, separate
+mode (`--embed-summaries`) embeds existing summaries with bge-m3 via Ollama, reusing
+`chunk_embed.embed_chunk` 1:1 — writing and embedding are split so either can be re-run
+without redoing the other (SOLARIA asleep blocks embedding, not writing; API downtime blocks
+writing, not embedding).
+
+Long documents (plan §1.2 outlier: ~360k chars) exceed practical LLM context: chunks are
+grouped ~20-at-a-time into partial summaries (plain text, no JSON), then a final pass
+synthesizes those partials with the normal JSON prompt. Counted separately
+(`documents_mapreduce`), never silently skipped.
+
+Runs on PIHA (rsync `src/` + `tags-vocab.yaml` to `/tmp`, per plan §1.4) against
+kb-postgres@PIHA and OLLAMA_URL=http://solaria:11434, or on SOLARIA directly for the local
+backend. Anthropic backend needs `ANTHROPIC_API_KEY` in the environment for the run only —
+never logged, never written to disk.
+
+Usage:
+    # Dry run (default) — fetch, chunk-concat, count; no LLM calls, no DB writes:
+    documents-ingest-summarize --dsn ... --backend ollama --model gemma3:12b
+
+    # Real run, local track:
+    documents-ingest-summarize --dsn ... --backend ollama --model gemma3:12b --apply
+
+    # Real run, API track (ANTHROPIC_API_KEY must be set):
+    documents-ingest-summarize --dsn ... --backend anthropic --model claude-haiku-4-5 --apply
+
+    # Embed existing summaries (bge-m3, second pass):
+    documents-ingest-summarize --dsn ... --embed-summaries --embed-model bge-m3 --apply
+"""
+from __future__ import annotations
+
+import argparse
+import asyncio
+import json
+import os
+import re
+import sys
+import unicodedata
+from pathlib import Path
+from typing import Optional, Protocol
+
+import aiohttp
+import asyncpg
+import structlog
+import yaml
+from anthropic import AsyncAnthropic
+
+from documents_ingest.chunk_embed import (
+    EmbeddingDimensionError,
+    EXPECTED_DIM,
+    _vector_literal,
+    embed_chunk,
+)
+
+_log = structlog.get_logger(__name__)
+
+DEFAULT_OLLAMA_URL = "http://localhost:11434"
+DEFAULT_EMBED_MODEL = "bge-m3"
+DEFAULT_MAX_TOKENS = 2048
+DEFAULT_CHUNKS_PER_GROUP = 20
+
+# Ollama's *runtime* context window defaults to a few thousand tokens regardless of a
+# model's advertised max (gemma3:12b advertises 131072) -- confirmed empirically during the
+# pilot: a 93k-char OWU document was silently truncated to prompt_eval_count=2051 tokens with
+# no num_ctx set, and the resulting summary described the document's tail (a RODO clause)
+# instead of its actual insurance terms. `options.num_ctx` must be set explicitly on every
+# call, sized to the prompt -- never left to Ollama's default.
+OLLAMA_CHARS_PER_TOKEN = 3.0  # conservative for diacritic-heavy Polish text
+OLLAMA_MIN_NUM_CTX = 4096
+OLLAMA_MAX_NUM_CTX = 131072  # gemma3:12b's advertised context_length
+OLLAMA_CTX_RESPONSE_RESERVE = 4096  # headroom for template + generated output
+
+
+def compute_num_ctx(prompt_chars: int) -> int:
+    """Size Ollama's num_ctx to the actual prompt, rounded up to a 1024-token step (stable
+    KV-cache allocation), clamped to [OLLAMA_MIN_NUM_CTX, OLLAMA_MAX_NUM_CTX]."""
+    needed = int(prompt_chars / OLLAMA_CHARS_PER_TOKEN) + OLLAMA_CTX_RESPONSE_RESERVE
+    needed = ((needed + 1023) // 1024) * 1024
+    return max(OLLAMA_MIN_NUM_CTX, min(OLLAMA_MAX_NUM_CTX, needed))
+# Plan §1.2: the pilot corpus has one ~360k-char outlier; everything else is far smaller.
+# This threshold only exists to catch that shape of document, not to tune routine chunking.
+DEFAULT_MAPREDUCE_THRESHOLD_CHARS = 200_000
+DEFAULT_TAGS_VOCAB_PATH = Path(__file__).resolve().parent.parent.parent / "tags-vocab.yaml"
+
+SYSTEM_PROMPT = (
+    "Jesteś archiwistą domowej bazy wiedzy. Streszczasz dokumenty po polsku, zwięźle i "
+    "faktograficznie: kto, co, kiedy, kwoty, numery umów/polis, terminy. Nie zgadujesz — "
+    "czego nie ma w tekście, tego nie piszesz. Zwracasz wyłącznie JSON."
+)
+
+PARTIAL_SYSTEM_PROMPT = (
+    "Jesteś archiwistą domowej bazy wiedzy. Streszczasz fragment dłuższego dokumentu po "
+    "polsku w 2-4 zdaniach, wypisując wszystkie fakty: kwoty, daty, numery, strony. To "
+    "streszczenie częściowe zostanie później połączone z innymi częściami tego samego "
+    "dokumentu — nie pomijaj konkretów. Odpowiadasz czystym tekstem, bez JSON."
+)
+
+SUMMARY_JSON_SCHEMA = {
+    "type": "object",
+    "properties": {
+        "summary": {"type": "string"},
+        "tags": {"type": "array", "items": {"type": "string"}},
+    },
+    "required": ["summary", "tags"],
+    "additionalProperties": False,
+}
+
+_INSERT_SQL = """
+INSERT INTO document_summary (envelope_id, summary, tags, model)
+VALUES ($1, $2, $3::jsonb, $4)
+ON CONFLICT (envelope_id, model) DO NOTHING
+"""
+
+_TAG_CLEAN_RE = re.compile(r"[^\w-]+", re.UNICODE)
+_TAG_DASH_COLLAPSE_RE = re.compile(r"-{2,}")
+
+
+class LLMBackend(Protocol):
+    """A backend answers one prompt at a time. `json_mode=True` requests forced-JSON output
+    (final summary+tags call); `json_mode=False` is a plain-text call (map-reduce partials)."""
+
+    async def complete(self, system: str, user: str, json_mode: bool = True) -> str: ...
+
+
+class OllamaBackend:
+    def __init__(self, session: aiohttp.ClientSession, base_url: str, model: str):
+        self.session = session
+        self.base_url = base_url
+        self.model = model
+
+    async def complete(self, system: str, user: str, json_mode: bool = True) -> str:
+        num_ctx = compute_num_ctx(len(system) + len(user))
+        payload = {
+            "model": self.model,
+            "messages": [
+                {"role": "system", "content": system},
+                {"role": "user", "content": user},
+            ],
+            "stream": False,
+            "options": {"temperature": 0, "num_ctx": num_ctx},
+        }
+        if json_mode:
+            payload["format"] = "json"
+        async with self.session.post(f"{self.base_url}/api/chat", json=payload) as resp:
+            resp.raise_for_status()
+            data = await resp.json()
+        return data["message"]["content"]
+
+
+class AnthropicBackend:
+    def __init__(self, client, model: str, max_tokens: int = DEFAULT_MAX_TOKENS):
+        self.client = client
+        self.model = model
+        self.max_tokens = max_tokens
+
+    async def complete(self, system: str, user: str, json_mode: bool = True) -> str:
+        kwargs = {}
+        if json_mode:
+            kwargs["output_config"] = {
+                "format": {"type": "json_schema", "schema": SUMMARY_JSON_SCHEMA}
+            }
+        response = await self.client.messages.create(
+            model=self.model,
+            max_tokens=self.max_tokens,
+            temperature=0,
+            system=system,
+            messages=[{"role": "user", "content": user}],
+            **kwargs,
+        )
+        return next((b.text for b in response.content if b.type == "text"), "")
+
+
+def load_tags_vocab(path: Path) -> list[str]:
+    """Controlled tag vocabulary (plan §2 decision 4) — a versioned YAML list."""
+    with open(path, encoding="utf-8") as f:
+        data = yaml.safe_load(f)
+    return list(data.get("tags", []))
+
+
+def build_user_prompt(vocab: list[str], content: str) -> str:
+    return (
+        "Słownik kontrolowany tagów (WYBIERZ Z TEJ LISTY w pierwszej kolejności, maks. 3 "
+        "najtrafniejsze pozycje, dokładnie w tym zapisie):\n"
+        f"{', '.join(vocab)}\n\n"
+        "Dopiero jeśli żaden z powyższych tagów nie pasuje do dokumentu, możesz dodać maks. "
+        "3 dodatkowe tagi spoza listy — one też MUSZĄ być PO POLSKU, małymi literami, "
+        "kebab-case (np. \"wspolnota-mieszkaniowa\", nie \"community\" ani \"HOA\"). "
+        "Nigdy nie zwracaj tagów po angielsku.\n\n"
+        "Treść dokumentu:\n"
+        f"{content}\n\n"
+        'Zwróć JSON: {"summary": "<3-8 zdań PO POLSKU>", "tags": ["tag1", "tag2", ...]}'
+    )
+
+
+def build_partial_prompt(group_text: str, idx: int, total: int) -> str:
+    return (
+        f"Fragment dokumentu, część {idx}/{total}:\n\n{group_text}\n\n"
+        "Streść ten fragment w 2-4 zdaniach po polsku, z konkretami (kwoty, daty, numery)."
+    )
+
+
+def is_duplicate(entities: list) -> bool:
+    """`entities[type=duplicate_of]` (plan §3.2 / §5.1) — duplicate envelopes are skipped
+    whole, never summarized even partially."""
+    return any(
+        isinstance(e, dict) and e.get("type") == "duplicate_of" for e in (entities or [])
+    )
+
+
+def normalize_tag(tag: str) -> str:
+    """lowercase, kebab-case, NFC (plan §2 decision 4)."""
+    t = unicodedata.normalize("NFC", tag.strip().lower())
+    t = t.replace(" ", "-")
+    t = _TAG_CLEAN_RE.sub("-", t)
+    t = _TAG_DASH_COLLAPSE_RE.sub("-", t)
+    return t.strip("-")
+
+
+def normalize_and_validate_tags(raw_tags: list, vocab: list[str]) -> tuple[list[str], int]:
+    """Normalizes + dedupes tags; vocab tags are kept in full, free-form tags capped at 3
+    (plan §2 decision 4). Returns (final_tags, truncated_count) — truncated_count is
+    informational only, not part of the stats balance invariant."""
+    vocab_set = set(vocab)
+    seen: list[str] = []
+    for raw in raw_tags or []:
+        if not isinstance(raw, str):
+            continue
+        norm = normalize_tag(raw)
+        if norm and norm not in seen:
+            seen.append(norm)
+
+    vocab_tags = [t for t in seen if t in vocab_set]
+    freeform = [t for t in seen if t not in vocab_set]
+    truncated = max(0, len(freeform) - 3)
+    return vocab_tags + freeform[:3], truncated
+
+
+async def fetch_documents(conn: asyncpg.Connection, limit: Optional[int], offset: Optional[int]) -> list:
+    """`source='paperless'` envelopes, ordered by id for stable --limit/--offset slicing."""
+    query = "SELECT id, entities FROM envelope WHERE source = 'paperless' ORDER BY id"
+    params: list = []
+    if limit is not None:
+        params.append(limit)
+        query += f" LIMIT ${len(params)}"
+    if offset:
+        params.append(offset)
+        query += f" OFFSET ${len(params)}"
+    return await conn.fetch(query, *params)
+
+
+async def fetch_active_chunk_texts(conn: asyncpg.Connection, envelope_id: str) -> list[str]:
+    """`document_chunk.text WHERE excluded_reason IS NULL` (plan §5.1) — junk and duplicate
+    chunks never enter a summary."""
+    rows = await conn.fetch(
+        "SELECT text FROM document_chunk WHERE envelope_id = $1 AND excluded_reason IS NULL "
+        "ORDER BY chunk_index",
+        envelope_id,
+    )
+    return [r["text"] for r in rows]
+
+
+async def fetch_existing_summary_keys(conn: asyncpg.Connection, model: str) -> set[str]:
+    """envelope_ids already summarized with this `model` — idempotency + dry-run preview."""
+    rows = await conn.fetch("SELECT envelope_id FROM document_summary WHERE model = $1", model)
+    return {r["envelope_id"] for r in rows}
+
+
+def _decode_jsonb(value: object) -> object:
+    if value is None:
+        return None
+    if isinstance(value, str):
+        return json.loads(value)
+    return value
+
+
+async def get_summary_and_tags(
+    backend: LLMBackend, system: str, user: str, retries: int = 1
+) -> Optional[dict]:
+    """Forced-JSON call with one retry on invalid JSON/schema (plan §5.1). Returns None
+    (caller counts `llm_errors`) after `retries` failed attempts."""
+    for attempt in range(retries + 1):
+        try:
+            raw = await backend.complete(system, user, json_mode=True)
+            data = json.loads(raw)
+        except Exception:
+            data = None
+
+        if (
+            isinstance(data, dict)
+            and isinstance(data.get("summary"), str)
+            and isinstance(data.get("tags"), list)
+        ):
+            return data
+
+        if attempt < retries:
+            user = (
+                user
+                + "\n\nUWAGA: Poprzednia odpowiedź nie była poprawnym JSON zgodnym ze "
+                "schematem. Zwróć WYŁĄCZNIE poprawny JSON, bez dodatkowego tekstu."
+            )
+    return None
+
+
+async def summarize_mapreduce(
+    backend: LLMBackend, chunks: list[str], group_size: int
+) -> Optional[str]:
+    """Groups chunks ~`group_size`-at-a-time into partial summaries (plain text), returns
+    their concatenation as the "content" fed into the final JSON summarization pass. Returns
+    None if any partial call fails — caller counts the whole document as `llm_errors`, never
+    silently drops a partial."""
+    groups = [chunks[i : i + group_size] for i in range(0, len(chunks), group_size)]
+    partials: list[str] = []
+    for idx, group in enumerate(groups, start=1):
+        group_text = "\n\n".join(group)
+        try:
+            partial = await backend.complete(
+                PARTIAL_SYSTEM_PROMPT,
+                build_partial_prompt(group_text, idx, len(groups)),
+                json_mode=False,
+            )
+        except Exception:
+            _log.warning("skip.mapreduce_partial_error", group_index=idx, group_total=len(groups))
+            return None
+        partial = partial.strip()
+        if not partial:
+            _log.warning("skip.mapreduce_partial_empty", group_index=idx, group_total=len(groups))
+            return None
+        partials.append(partial)
+    return "\n\n".join(partials)
+
+
+async def insert_summary(
+    conn: asyncpg.Connection, envelope_id: str, summary: str, tags: list[str], model: str
+) -> str:
+    """Returns asyncpg's command tag so the caller can tell a real insert from an
+    ON CONFLICT no-op (second line of defense behind the pre-fetched `existing` set)."""
+    return await conn.execute(_INSERT_SQL, envelope_id, summary, json.dumps(tags), model)
+
+
+def _rows_affected(command_tag: str) -> int:
+    return int(command_tag.rsplit(" ", 1)[-1])
+
+
+async def run_summarize(
+    dsn: str,
+    backend_name: str,
+    model: str,
+    ollama_url: str = DEFAULT_OLLAMA_URL,
+    anthropic_api_key: Optional[str] = None,
+    tags_vocab_path: Path = DEFAULT_TAGS_VOCAB_PATH,
+    limit: Optional[int] = None,
+    offset: Optional[int] = None,
+    apply: bool = False,
+    max_tokens: int = DEFAULT_MAX_TOKENS,
+    chunks_per_group: int = DEFAULT_CHUNKS_PER_GROUP,
+    mapreduce_threshold_chars: int = DEFAULT_MAPREDUCE_THRESHOLD_CHARS,
+) -> dict:
+    """Summarize+tag one --limit/--offset slice of `source='paperless'` envelopes into
+    `document_summary` under `model`.
+
+    Stats must balance:
+        documents_fetched = duplicates_skipped + no_active_chunks + already_summarized
+                             + summarized + llm_errors
+
+    `duplicates_skipped` (envelope has `entities[type=duplicate_of]`) and `no_active_chunks`
+    (zero `document_chunk` rows with `excluded_reason IS NULL`) are both counted before any
+    LLM call — dry-run and apply agree on this split even though dry-run never calls the LLM.
+    A failed DB insert (rare — the pre-fetched `existing` set is the first line of defense
+    against duplicate work) is folded into `llm_errors`, same as `chunk_embed.py`'s
+    `chunks_errors` covers both embed and insert failures.
+    """
+    stats = {
+        "documents_fetched": 0,
+        "duplicates_skipped": 0,
+        "no_active_chunks": 0,
+        "already_summarized": 0,
+        "summarized": 0,
+        "llm_errors": 0,
+        "documents_mapreduce": 0,
+        "tags_truncated": 0,
+    }
+
+    conn = await asyncpg.connect(dsn)
+    try:
+        docs = await fetch_documents(conn, limit, offset)
+        existing = await fetch_existing_summary_keys(conn, model)
+        vocab = load_tags_vocab(tags_vocab_path)
+
+        session: Optional[aiohttp.ClientSession] = None
+        client = None
+        backend: Optional[LLMBackend] = None
+        if apply:
+            if backend_name == "ollama":
+                session = aiohttp.ClientSession(timeout=aiohttp.ClientTimeout(total=300))
+                backend = OllamaBackend(session, ollama_url, model)
+            else:
+                client = AsyncAnthropic(api_key=anthropic_api_key)
+                backend = AnthropicBackend(client, model, max_tokens)
+
+        try:
+            for row in docs:
+                stats["documents_fetched"] += 1
+                envelope_id = row["id"]
+                entities = _decode_jsonb(row["entities"]) or []
+
+                if is_duplicate(entities):
+                    stats["duplicates_skipped"] += 1
+                    continue
+
+                if envelope_id in existing:
+                    stats["already_summarized"] += 1
+                    continue
+
+                chunks = await fetch_active_chunk_texts(conn, envelope_id)
+                content = "\n\n".join(chunks).strip()
+                if not content:
+                    stats["no_active_chunks"] += 1
+                    continue
+
+                if not apply:
+                    stats["summarized"] += 1
+                    continue
+
+                assert backend is not None
+                if len(content) > mapreduce_threshold_chars:
+                    stats["documents_mapreduce"] += 1
+                    content = await summarize_mapreduce(backend, chunks, chunks_per_group)
+                    if content is None:
+                        stats["llm_errors"] += 1
+                        continue
+
+                user_prompt = build_user_prompt(vocab, content)
+                data = await get_summary_and_tags(backend, SYSTEM_PROMPT, user_prompt)
+                if data is None:
+                    stats["llm_errors"] += 1
+                    _log.warning("skip.llm_error", envelope_id=envelope_id)
+                    continue
+
+                tags, truncated = normalize_and_validate_tags(data["tags"], vocab)
+                stats["tags_truncated"] += truncated
+
+                try:
+                    command_tag = await insert_summary(conn, envelope_id, data["summary"], tags, model)
+                except Exception:
+                    _log.warning("skip.insert_error", envelope_id=envelope_id, exc_info=True)
+                    stats["llm_errors"] += 1
+                    continue
+
+                existing.add(envelope_id)
+                if _rows_affected(command_tag) == 0:
+                    # ON CONFLICT no-op: the pre-fetched `existing` set should make this rare;
+                    # treat it the same as already-summarized rather than adding a bucket the
+                    # plan's balance formula doesn't have.
+                    stats["already_summarized"] += 1
+                else:
+                    stats["summarized"] += 1
+        finally:
+            if session is not None:
+                await session.close()
+            if client is not None:
+                await client.close()
+    finally:
+        await conn.close()
+
+    balance = (
+        stats["duplicates_skipped"]
+        + stats["no_active_chunks"]
+        + stats["already_summarized"]
+        + stats["summarized"]
+        + stats["llm_errors"]
+    )
+    if balance != stats["documents_fetched"]:
+        _log.error("stats_mismatch", **stats)
+
+    _log.info("run_complete", apply=apply, backend=backend_name, model=model, **stats)
+    return stats
+
+
+async def run_embed_summaries(
+    dsn: str,
+    ollama_url: str = DEFAULT_OLLAMA_URL,
+    embed_model: str = DEFAULT_EMBED_MODEL,
+    model_filter: Optional[str] = None,
+    limit: Optional[int] = None,
+    offset: Optional[int] = None,
+    apply: bool = False,
+) -> dict:
+    """Second, separate pass: embeds `document_summary.summary` (bge-m3, via Ollama) for
+    rows with `embedding IS NULL`. Reuses `chunk_embed.embed_chunk` — same Ollama
+    `/api/embeddings` call, same dimension guard. `--model` (the summarizing model) filters
+    which track to embed; omit to embed both tracks' pending rows in one run.
+
+    Stats must balance: summaries_fetched = embedded + errors
+    """
+    stats = {"summaries_fetched": 0, "embedded": 0, "errors": 0}
+
+    query = "SELECT id, summary FROM document_summary WHERE embedding IS NULL"
+    params: list = []
+    if model_filter:
+        params.append(model_filter)
+        query += f" AND model = ${len(params)}"
+    query += " ORDER BY id"
+    if limit is not None:
+        params.append(limit)
+        query += f" LIMIT ${len(params)}"
+    if offset:
+        params.append(offset)
+        query += f" OFFSET ${len(params)}"
+
+    conn = await asyncpg.connect(dsn)
+    try:
+        rows = await conn.fetch(query, *params)
+
+        session: Optional[aiohttp.ClientSession] = None
+        if apply:
+            session = aiohttp.ClientSession(timeout=aiohttp.ClientTimeout(total=120))
+
+        try:
+            for row in rows:
+                stats["summaries_fetched"] += 1
+                if not apply:
+                    stats["embedded"] += 1
+                    continue
+
+                assert session is not None
+                try:
+                    embedding, _elapsed = await embed_chunk(session, ollama_url, embed_model, row["summary"])
+                except Exception:
+                    _log.warning("skip.embed_error", summary_id=row["id"], exc_info=True)
+                    stats["errors"] += 1
+                    continue
+
+                if len(embedding) != EXPECTED_DIM:
+                    raise EmbeddingDimensionError(
+                        f"ollama model={embed_model!r} returned dim={len(embedding)}, "
+                        f"expected {EXPECTED_DIM}"
+                    )
+
+                try:
+                    await conn.execute(
+                        "UPDATE document_summary SET embedding = $1::vector, embedding_model = $2 "
+                        "WHERE id = $3",
+                        _vector_literal(embedding),
+                        embed_model,
+                        row["id"],
+                    )
+                except Exception:
+                    _log.warning("skip.update_error", summary_id=row["id"], exc_info=True)
+                    stats["errors"] += 1
+                    continue
+
+                stats["embedded"] += 1
+        finally:
+            if session is not None:
+                await session.close()
+    finally:
+        await conn.close()
+
+    if stats["embedded"] + stats["errors"] != stats["summaries_fetched"]:
+        _log.error("stats_mismatch", **stats)
+
+    _log.info("run_complete", apply=apply, embed_model=embed_model, **stats)
+    return stats
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(
+        description="Summarize+tag source='paperless' documents into document_summary, or "
+        "embed existing summaries with --embed-summaries (module 5, phase 3, plan §5)."
+    )
+    parser.add_argument("--dsn", default=os.environ.get("KB_DSN"),
+                        help="asyncpg DSN for kb-postgres (or set KB_DSN env var)")
+    parser.add_argument("--limit", type=int, default=None, help="Max documents/summaries to process")
+    parser.add_argument("--offset", type=int, default=0, help="Slice offset, ordered by id")
+    parser.add_argument("--apply", action="store_true",
+                        help="Actually call the LLM/Ollama and write rows. Default is dry-run.")
+
+    parser.add_argument("--embed-summaries", action="store_true",
+                        help="Embed existing document_summary rows (bge-m3) instead of writing new ones.")
+    parser.add_argument("--embed-model", default=os.environ.get("SUMMARY_EMBED_MODEL", DEFAULT_EMBED_MODEL),
+                        help=f"Ollama embedding model for --embed-summaries (default: {DEFAULT_EMBED_MODEL})")
+
+    parser.add_argument("--backend", choices=["ollama", "anthropic"],
+                        help="LLM backend for writing summaries (required unless --embed-summaries)")
+    parser.add_argument("--model", help="Backend model name, e.g. gemma3:12b or claude-haiku-4-5 "
+                        "(writing mode); or a filter on document_summary.model (--embed-summaries)")
+    parser.add_argument("--ollama-url", default=os.environ.get("OLLAMA_URL", DEFAULT_OLLAMA_URL),
+                        help=f"Ollama base URL (default: {DEFAULT_OLLAMA_URL}, or set OLLAMA_URL)")
+    parser.add_argument("--anthropic-api-key", default=os.environ.get("ANTHROPIC_API_KEY"),
+                        help="Anthropic API key (or set ANTHROPIC_API_KEY env var) — never logged")
+    parser.add_argument("--tags-vocab", type=Path, default=DEFAULT_TAGS_VOCAB_PATH,
+                        help=f"Path to tags-vocab.yaml (default: {DEFAULT_TAGS_VOCAB_PATH})")
+    parser.add_argument("--max-tokens", type=int, default=DEFAULT_MAX_TOKENS,
+                        help=f"Anthropic max_tokens (default: {DEFAULT_MAX_TOKENS})")
+    parser.add_argument("--chunks-per-group", type=int, default=DEFAULT_CHUNKS_PER_GROUP,
+                        help=f"Map-reduce group size in chunks (default: {DEFAULT_CHUNKS_PER_GROUP})")
+    parser.add_argument("--mapreduce-threshold-chars", type=int, default=DEFAULT_MAPREDUCE_THRESHOLD_CHARS,
+                        help=f"Content length above which map-reduce kicks in (default: {DEFAULT_MAPREDUCE_THRESHOLD_CHARS})")
+    args = parser.parse_args()
+
+    if not args.dsn:
+        _log.error("missing_dsn", hint="pass --dsn or set KB_DSN")
+        sys.exit(1)
+
+    if args.embed_summaries:
+        stats = asyncio.run(
+            run_embed_summaries(
+                dsn=args.dsn,
+                ollama_url=args.ollama_url,
+                embed_model=args.embed_model,
+                model_filter=args.model,
+                limit=args.limit,
+                offset=args.offset,
+                apply=args.apply,
+            )
+        )
+        mode = "APPLY" if args.apply else "DRY-RUN"
+        _log.info("summary", mode=mode, **stats)
+        balanced = stats["embedded"] + stats["errors"] == stats["summaries_fetched"]
+        sys.exit(1 if (stats["errors"] > 0 or not balanced) else 0)
+
+    if not args.backend or not args.model:
+        _log.error("missing_backend_or_model", hint="--backend and --model are required unless --embed-summaries")
+        sys.exit(1)
+    if args.backend == "anthropic" and args.apply and not args.anthropic_api_key:
+        _log.error("missing_anthropic_api_key", hint="pass --anthropic-api-key or set ANTHROPIC_API_KEY")
+        sys.exit(1)
+    if not args.tags_vocab.exists():
+        _log.error("missing_tags_vocab", path=str(args.tags_vocab))
+        sys.exit(1)
+
+    try:
+        stats = asyncio.run(
+            run_summarize(
+                dsn=args.dsn,
+                backend_name=args.backend,
+                model=args.model,
+                ollama_url=args.ollama_url,
+                anthropic_api_key=args.anthropic_api_key,
+                tags_vocab_path=args.tags_vocab,
+                limit=args.limit,
+                offset=args.offset,
+                apply=args.apply,
+                max_tokens=args.max_tokens,
+                chunks_per_group=args.chunks_per_group,
+                mapreduce_threshold_chars=args.mapreduce_threshold_chars,
+            )
+        )
+    except EmbeddingDimensionError as exc:
+        _log.error("dim_mismatch_abort", error=str(exc))
+        sys.exit(1)
+
+    mode = "APPLY" if args.apply else "DRY-RUN"
+    _log.info("summary", mode=mode, backend=args.backend, model=args.model, **stats)
+
+    balanced = stats["documents_fetched"] == (
+        stats["duplicates_skipped"] + stats["no_active_chunks"] + stats["already_summarized"]
+        + stats["summarized"] + stats["llm_errors"]
+    )
+    failed = stats["llm_errors"] > 0 or not balanced
+    sys.exit(1 if failed else 0)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/jobs/documents-ingest/tags-vocab.yaml b/jobs/documents-ingest/tags-vocab.yaml
new file mode 100644
index 0000000..1d4ad1d
--- /dev/null
+++ b/jobs/documents-ingest/tags-vocab.yaml
@@ -0,0 +1,20 @@
+# Controlled tag vocabulary for document_summary.tags (module 5, phase 3, plan §2 decision 4).
+# Prompt forces the model to pick from this list; up to 3 extra free-form tags are allowed
+# per document (normalized lowercase/kebab-case/NFC), the rest truncated (`tags_truncated`).
+# After the pilot: review free-form tags via `jsonb_array_elements` + count, promote frequent
+# ones here. Versioned — changes to this list are a deliberate, reviewable diff.
+tags:
+  - ubezpieczenie
+  - bank
+  - kredyt
+  - faktura
+  - umowa
+  - urzad
+  - auto
+  - nieruchomosc
+  - zdrowie
+  - szkola
+  - fll
+  - praca
+  - subskrypcja
+  - regulamin
diff --git a/jobs/documents-ingest/tests/test_summarize.py b/jobs/documents-ingest/tests/test_summarize.py
new file mode 100644
index 0000000..03c2011
--- /dev/null
+++ b/jobs/documents-ingest/tests/test_summarize.py
@@ -0,0 +1,586 @@
+"""Unit tests for the summarize+tag job — no DB, no real HTTP, no real Ollama/Anthropic."""
+from __future__ import annotations
+
+import json
+
+import pytest
+
+from documents_ingest.summarize import (
+    DEFAULT_TAGS_VOCAB_PATH,
+    OLLAMA_MAX_NUM_CTX,
+    OLLAMA_MIN_NUM_CTX,
+    build_partial_prompt,
+    build_user_prompt,
+    compute_num_ctx,
+    get_summary_and_tags,
+    insert_summary,
+    is_duplicate,
+    load_tags_vocab,
+    normalize_and_validate_tags,
+    normalize_tag,
+    run_embed_summaries,
+    run_summarize,
+    summarize_mapreduce,
+)
+
+VOCAB = ["ubezpieczenie", "bank", "faktura"]
+
+
+def _envelope_row(envelope_id, entities=None):
+    return {"id": envelope_id, "entities": json.dumps(entities or [])}
+
+
+class TestComputeNumCtx:
+    def test_short_prompt_at_least_floor(self):
+        assert compute_num_ctx(100) >= OLLAMA_MIN_NUM_CTX
+
+    def test_zero_length_prompt_uses_floor(self):
+        assert compute_num_ctx(0) == OLLAMA_MIN_NUM_CTX
+
+    def test_scales_with_prompt_length(self):
+        # Regression case from the pilot: a 93k-char document was silently truncated to
+        # prompt_eval_count=2051 tokens by Ollama's runtime default -- num_ctx must scale
+        # well past that for a prompt this size.
+        ctx = compute_num_ctx(93_471)
+        assert ctx > 30_000
+
+    def test_huge_prompt_clamped_to_model_max(self):
+        assert compute_num_ctx(10_000_000) == OLLAMA_MAX_NUM_CTX
+
+    def test_rounds_up_to_1024_step(self):
+        assert compute_num_ctx(1000) % 1024 == 0
+
+
+class TestTagsVocab:
+    def test_default_vocab_file_loads_and_is_nonempty(self):
+        vocab = load_tags_vocab(DEFAULT_TAGS_VOCAB_PATH)
+        assert "ubezpieczenie" in vocab
+        assert len(vocab) >= 5
+
+
+class TestIsDuplicate:
+    def test_no_entities_not_duplicate(self):
+        assert is_duplicate([]) is False
+        assert is_duplicate(None) is False
+
+    def test_duplicate_of_entity_detected(self):
+        entities = [{"type": "content", "text": "x"}, {"type": "duplicate_of", "envelope_id": "paperless:14"}]
+        assert is_duplicate(entities) is True
+
+    def test_unrelated_entities_not_duplicate(self):
+        entities = [{"type": "content", "text": "x"}, {"type": "tag", "name": "faktura"}]
+        assert is_duplicate(entities) is False
+
+
+class TestNormalizeTag:
+    def test_lowercases_and_kebab_cases(self):
+        assert normalize_tag("  Ubezpieczenie Auto ") == "ubezpieczenie-auto"
+
+    def test_strips_punctuation(self):
+        assert normalize_tag("PZU!!") == "pzu"
+
+    def test_collapses_repeated_dashes(self):
+        assert normalize_tag("a   b") == "a-b"
+
+    def test_nfc_normalizes_diacritics(self):
+        # decomposed "s" + combining cedilla vs precomposed - should normalize the same way
+        import unicodedata
+        decomposed = unicodedata.normalize("NFD", "ś") + "rodowisko"  # "ś" decomposed
+        assert normalize_tag(decomposed) == normalize_tag("środowisko")
+
+
+class TestNormalizeAndValidateTags:
+    def test_keeps_all_vocab_tags(self):
+        tags, truncated = normalize_and_validate_tags(["bank", "faktura"], VOCAB)
+        assert tags == ["bank", "faktura"]
+        assert truncated == 0
+
+    def test_caps_freeform_at_three(self):
+        raw = ["bank", "polisa", "pzu", "auto-osobowe", "extra-one"]
+        tags, truncated = normalize_and_validate_tags(raw, VOCAB)
+        assert tags[0] == "bank"
+        assert len(tags) == 1 + 3  # 1 vocab + 3 freeform kept
+        assert truncated == 1  # "extra-one" dropped
+
+    def test_dedupes_after_normalization(self):
+        tags, truncated = normalize_and_validate_tags(["Bank", "bank", " bank "], VOCAB)
+        assert tags == ["bank"]
+        assert truncated == 0
+
+    def test_ignores_non_string_entries(self):
+        tags, truncated = normalize_and_validate_tags(["bank", 123, None], VOCAB)
+        assert tags == ["bank"]
+
+
+class TestPromptBuilders:
+    def test_user_prompt_includes_vocab_and_content(self):
+        prompt = build_user_prompt(VOCAB, "treść dokumentu")
+        assert "ubezpieczenie" in prompt
+        assert "treść dokumentu" in prompt
+        assert "JSON" in prompt
+
+    def test_partial_prompt_includes_index_and_total(self):
+        prompt = build_partial_prompt("fragment", 2, 5)
+        assert "2/5" in prompt
+        assert "fragment" in prompt
+
+
+class _FakeChatResponse:
+    def __init__(self, payload, status=200):
+        self._payload = payload
+        self._status = status
+
+    async def __aenter__(self):
+        return self
+
+    async def __aexit__(self, *exc):
+        return False
+
+    async def json(self):
+        return self._payload
+
+    def raise_for_status(self):
+        if self._status >= 400:
+            raise RuntimeError(f"HTTP {self._status}")
+
+
+class _FakeOllamaChatSession:
+    """Serves a queue of /api/chat responses, one per call (in order)."""
+
+    def __init__(self, contents: list[str]):
+        self._contents = list(contents)
+        self.requests: list[dict] = []
+
+    def post(self, url, json):
+        self.requests.append({"url": url, "json": json})
+        content = self._contents.pop(0)
+        return _FakeChatResponse({"message": {"content": content}})
+
+    async def close(self):
+        pass
+
+
+class _FakeBackend:
+    """A scripted LLMBackend: returns queued responses in order, regardless of prompt."""
+
+    def __init__(self, responses: list[str]):
+        self._responses = list(responses)
+        self.calls: list[tuple] = []
+
+    async def complete(self, system, user, json_mode=True):
+        self.calls.append((system, user, json_mode))
+        return self._responses.pop(0)
+
+
+class _FailingBackend:
+    async def complete(self, system, user, json_mode=True):
+        raise RuntimeError("boom")
+
+
+class TestGetSummaryAndTags:
+    async def test_valid_json_first_try(self):
+        backend = _FakeBackend([json.dumps({"summary": "s", "tags": ["bank"]})])
+        data = await get_summary_and_tags(backend, "sys", "user")
+        assert data == {"summary": "s", "tags": ["bank"]}
+        assert len(backend.calls) == 1
+
+    async def test_invalid_json_then_valid_on_retry(self):
+        backend = _FakeBackend(["not json", json.dumps({"summary": "s", "tags": []})])
+        data = await get_summary_and_tags(backend, "sys", "user")
+        assert data == {"summary": "s", "tags": []}
+        assert len(backend.calls) == 2
+
+    async def test_missing_keys_counts_as_invalid(self):
+        backend = _FakeBackend([json.dumps({"summary": "s"}), json.dumps({"summary": "s", "tags": []})])
+        data = await get_summary_and_tags(backend, "sys", "user")
+        assert data == {"summary": "s", "tags": []}
+
+    async def test_gives_up_after_retries_exhausted(self):
+        backend = _FakeBackend(["not json", "still not json"])
+        data = await get_summary_and_tags(backend, "sys", "user", retries=1)
+        assert data is None
+
+    async def test_backend_exception_is_treated_as_invalid(self):
+        data = await get_summary_and_tags(_FailingBackend(), "sys", "user", retries=0)
+        assert data is None
+
+
+class TestSummarizeMapreduce:
+    async def test_combines_partials_in_order(self):
+        backend = _FakeBackend(["partial one", "partial two"])
+        result = await summarize_mapreduce(backend, ["c1", "c2", "c3"], group_size=2)
+        assert result == "partial one\n\npartial two"
+        # two groups of size 2 and 1 -> two calls, both plain-text (json_mode=False)
+        assert len(backend.calls) == 2
+        assert all(call[2] is False for call in backend.calls)
+
+    async def test_partial_failure_aborts_whole_document(self):
+        result = await summarize_mapreduce(_FailingBackend(), ["c1", "c2"], group_size=2)
+        assert result is None
+
+    async def test_empty_partial_aborts(self):
+        backend = _FakeBackend(["   "])
+        result = await summarize_mapreduce(backend, ["c1"], group_size=2)
+        assert result is None
+
+
+class TestInsertSql:
+    def test_on_conflict_target_includes_model(self):
+        from documents_ingest.summarize import _INSERT_SQL
+        assert "ON CONFLICT (envelope_id, model)" in _INSERT_SQL
+
+
+class _FakeConn:
+    """Fakes the three query shapes this job issues: envelope fetch, active-chunk-text
+    fetch, and existing-summary-keys fetch; plus execute() for INSERT/UPDATE."""
+
+    def __init__(self, docs=None, chunks_by_envelope=None, existing_summaries=None,
+                 existing_model="bge-m3", execute_results=None):
+        self._docs = docs or []
+        self._chunks_by_envelope = chunks_by_envelope or {}
+        self._existing_summaries = list(existing_summaries or [])
+        self._existing_model = existing_model
+        self._execute_results = list(execute_results) if execute_results is not None else None
+        self.execute_calls: list[tuple] = []
+
+    async def fetch(self, query, *params):
+        if "FROM document_chunk" in query:
+            envelope_id = params[0]
+            return [{"text": t} for t in self._chunks_by_envelope.get(envelope_id, [])]
+        if "FROM document_summary" in query:
+            if params and params[0] != self._existing_model:
+                return []
+            return [{"envelope_id": eid} for eid in self._existing_summaries]
+        return self._docs
+
+    async def execute(self, query, *params):
+        self.execute_calls.append(params)
+        if self._execute_results is not None:
+            return self._execute_results.pop(0)
+        return "INSERT 0 1"
+
+    async def close(self):
+        pass
+
+
+class TestRunSummarize:
+    def _patch(self, monkeypatch, conn, session=None):
+        async def _fake_connect(dsn):
+            return conn
+        monkeypatch.setattr("documents_ingest.summarize.asyncpg.connect", _fake_connect)
+        if session is not None:
+            def _fake_session_factory(*args, **kwargs):
+                return session
+            monkeypatch.setattr("documents_ingest.summarize.aiohttp.ClientSession", _fake_session_factory)
+
+    async def test_dry_run_counts_without_calling_backend_or_db(self, monkeypatch):
+        conn = _FakeConn(
+            docs=[_envelope_row("paperless:1")],
+            chunks_by_envelope={"paperless:1": ["treść dokumentu"]},
+        )
+        self._patch(monkeypatch, conn)
+        stats = await run_summarize(dsn="x", backend_name="ollama", model="gemma3:12b", apply=False)
+        assert stats["documents_fetched"] == 1
+        assert stats["summarized"] == 1
+        assert stats["llm_errors"] == 0
+        assert conn.execute_calls == []
+
+    async def test_duplicate_envelope_skipped_whole(self, monkeypatch):
+        conn = _FakeConn(
+            docs=[_envelope_row("paperless:74", entities=[{"type": "duplicate_of", "envelope_id": "paperless:14"}])],
+        )
+        self._patch(monkeypatch, conn)
+        stats = await run_summarize(dsn="x", backend_name="ollama", model="gemma3:12b", apply=False)
+        assert stats["duplicates_skipped"] == 1
+        assert stats["summarized"] == 0
+
+    async def test_no_active_chunks_counted_separately(self, monkeypatch):
+        conn = _FakeConn(docs=[_envelope_row("paperless:2")], chunks_by_envelope={})
+        self._patch(monkeypatch, conn)
+        stats = await run_summarize(dsn="x", backend_name="ollama", model="gemma3:12b", apply=False)
+        assert stats["no_active_chunks"] == 1
+        assert stats["summarized"] == 0
+
+    async def test_already_summarized_skipped(self, monkeypatch):
+        conn = _FakeConn(
+            docs=[_envelope_row("paperless:1")],
+            chunks_by_envelope={"paperless:1": ["text"]},
+            existing_summaries=["paperless:1"],
+            existing_model="gemma3:12b",
+        )
+        self._patch(monkeypatch, conn)
+        stats = await run_summarize(dsn="x", backend_name="ollama", model="gemma3:12b", apply=False)
+        assert stats["already_summarized"] == 1
+        assert stats["summarized"] == 0
+
+    async def test_apply_writes_summary_and_tags(self, monkeypatch):
+        conn = _FakeConn(
+            docs=[_envelope_row("paperless:1")],
+            chunks_by_envelope={"paperless:1": ["treść z kwotą 100 zł"]},
+        )
+        session = _FakeOllamaChatSession([json.dumps({"summary": "Streszczenie.", "tags": ["bank", "extra"]})])
+        self._patch(monkeypatch, conn, session)
+
+        stats = await run_summarize(dsn="x", backend_name="ollama", model="gemma3:12b", apply=True)
+
+        assert stats["summarized"] == 1
+        assert stats["llm_errors"] == 0
+        assert len(conn.execute_calls) == 1
+        envelope_id, summary, tags_json, model = conn.execute_calls[0]
+        assert envelope_id == "paperless:1"
+        assert summary == "Streszczenie."
+        assert json.loads(tags_json) == ["bank", "extra"]
+        assert model == "gemma3:12b"
+        # Regression guard: every Ollama call must carry an explicit num_ctx (plan §5.1
+        # limitation) -- Ollama's runtime default silently truncates long documents otherwise.
+        assert session.requests[0]["json"]["options"]["num_ctx"] >= OLLAMA_MIN_NUM_CTX
+
+    async def test_apply_with_anthropic_backend(self, monkeypatch):
+        conn = _FakeConn(
+            docs=[_envelope_row("paperless:1")],
+            chunks_by_envelope={"paperless:1": ["treść"]},
+        )
+
+        class _TextBlock:
+            type = "text"
+            text = json.dumps({"summary": "Streszczenie API.", "tags": ["faktura"]})
+
+        class _FakeResponse:
+            content = [_TextBlock()]
+
+        class _FakeMessages:
+            def __init__(self):
+                self.create_calls = []
+
+            async def create(self, **kwargs):
+                self.create_calls.append(kwargs)
+                return _FakeResponse()
+
+        class _FakeAsyncAnthropic:
+            def __init__(self, api_key=None):
+                self.api_key = api_key
+                self.messages = _FakeMessages()
+
+            async def close(self):
+                pass
+
+        fake_client_holder = {}
+
+        def _factory(api_key=None):
+            client = _FakeAsyncAnthropic(api_key=api_key)
+            fake_client_holder["client"] = client
+            return client
+
+        async def _fake_connect(dsn):
+            return conn
+        monkeypatch.setattr("documents_ingest.summarize.asyncpg.connect", _fake_connect)
+        monkeypatch.setattr("documents_ingest.summarize.AsyncAnthropic", _factory)
+
+        stats = await run_summarize(
+            dsn="x", backend_name="anthropic", model="claude-haiku-4-5",
+            anthropic_api_key="sk-fake", apply=True,
+        )
+
+        assert stats["summarized"] == 1
+        client = fake_client_holder["client"]
+        assert client.api_key == "sk-fake"
+        assert len(client.messages.create_calls) == 1
+        call = client.messages.create_calls[0]
+        assert call["model"] == "claude-haiku-4-5"
+        assert call["temperature"] == 0
+        assert call["output_config"]["format"]["type"] == "json_schema"
+
+    async def test_llm_error_isolated_and_counted(self, monkeypatch):
+        conn = _FakeConn(
+            docs=[_envelope_row("paperless:1"), _envelope_row("paperless:2")],
+            chunks_by_envelope={"paperless:1": ["a"], "paperless:2": ["b"]},
+        )
+        session = _FakeOllamaChatSession([
+            "not json", "still not json",  # paperless:1 exhausts retry -> llm_error
+            json.dumps({"summary": "ok", "tags": []}),  # paperless:2 succeeds
+        ])
+        self._patch(monkeypatch, conn, session)
+
+        stats = await run_summarize(dsn="x", backend_name="ollama", model="gemma3:12b", apply=True)
+
+        assert stats["documents_fetched"] == 2
+        assert stats["llm_errors"] == 1
+        assert stats["summarized"] == 1
+        assert len(conn.execute_calls) == 1  # only the successful one got inserted
+
+    async def test_conflict_skip_counted_as_already_summarized(self, monkeypatch):
+        conn = _FakeConn(
+            docs=[_envelope_row("paperless:1")],
+            chunks_by_envelope={"paperless:1": ["a"]},
+            execute_results=["INSERT 0 0"],  # ON CONFLICT DO NOTHING no-op
+        )
+        session = _FakeOllamaChatSession([json.dumps({"summary": "s", "tags": []})])
+        self._patch(monkeypatch, conn, session)
+
+        stats = await run_summarize(dsn="x", backend_name="ollama", model="gemma3:12b", apply=True)
+
+        assert stats["already_summarized"] == 1
+        assert stats["summarized"] == 0
+
+    async def test_stats_balance_invariant(self, monkeypatch):
+        conn = _FakeConn(
+            docs=[
+                _envelope_row("paperless:1", entities=[{"type": "duplicate_of", "envelope_id": "paperless:0"}]),
+                _envelope_row("paperless:2"),
+                _envelope_row("paperless:3"),
+            ],
+            chunks_by_envelope={"paperless:3": ["content"]},
+        )
+        self._patch(monkeypatch, conn)
+        stats = await run_summarize(dsn="x", backend_name="ollama", model="gemma3:12b", apply=False)
+        balance = (
+            stats["duplicates_skipped"] + stats["no_active_chunks"]
+            + stats["already_summarized"] + stats["summarized"] + stats["llm_errors"]
+        )
+        assert balance == stats["documents_fetched"] == 3
+
+    async def test_limit_and_offset_passed_through(self, monkeypatch):
+        class _Conn(_FakeConn):
+            async def fetch(self, query, *params):
+                if "FROM envelope" in query:
+                    self.captured = (query, params)
+                    return []
+                return await super().fetch(query, *params)
+
+        conn = _Conn()
+        self._patch(monkeypatch, conn)
+        await run_summarize(dsn="x", backend_name="ollama", model="gemma3:12b", limit=5, offset=10, apply=False)
+        query, params = conn.captured
+        assert "LIMIT" in query and "OFFSET" in query
+        assert params == (5, 10)
+
+    async def test_rerun_after_apply_writes_nothing_new(self, monkeypatch):
+        conn1 = _FakeConn(
+            docs=[_envelope_row("paperless:1")],
+            chunks_by_envelope={"paperless:1": ["a"]},
+        )
+        session1 = _FakeOllamaChatSession([json.dumps({"summary": "s", "tags": []})])
+        self._patch(monkeypatch, conn1, session1)
+        await run_summarize(dsn="x", backend_name="ollama", model="gemma3:12b", apply=True)
+
+        conn2 = _FakeConn(
+            docs=[_envelope_row("paperless:1")],
+            chunks_by_envelope={"paperless:1": ["a"]},
+            existing_summaries=["paperless:1"],
+            existing_model="gemma3:12b",
+        )
+        session2 = _FakeOllamaChatSession([])
+        self._patch(monkeypatch, conn2, session2)
+        stats2 = await run_summarize(dsn="x", backend_name="ollama", model="gemma3:12b", apply=True)
+
+        assert stats2["already_summarized"] == 1
+        assert stats2["summarized"] == 0
+
+
+class TestMapreduceIntegration:
+    def _patch(self, monkeypatch, conn, session=None):
+        async def _fake_connect(dsn):
+            return conn
+        monkeypatch.setattr("documents_ingest.summarize.asyncpg.connect", _fake_connect)
+        if session is not None:
+            monkeypatch.setattr("documents_ingest.summarize.aiohttp.ClientSession", lambda *a, **k: session)
+
+    async def test_long_document_triggers_mapreduce(self, monkeypatch):
+        long_chunks = ["x" * 100_000, "y" * 150_000]  # combined > threshold
+        conn = _FakeConn(
+            docs=[_envelope_row("paperless:1")],
+            chunks_by_envelope={"paperless:1": long_chunks},
+        )
+        session = _FakeOllamaChatSession([
+            "partial summary 1",  # map-reduce partial (plain text, one group covers both chunks)
+            json.dumps({"summary": "final", "tags": []}),  # final synthesis (JSON)
+        ])
+        self._patch(monkeypatch, conn, session)
+
+        stats = await run_summarize(
+            dsn="x", backend_name="ollama", model="gemma3:12b", apply=True,
+            mapreduce_threshold_chars=200_000, chunks_per_group=20,
+        )
+
+        assert stats["documents_mapreduce"] == 1
+        assert stats["summarized"] == 1
+        # first call has no "format" key (plain text), second has format=json
+        assert "format" not in session.requests[0]["json"]
+        assert session.requests[1]["json"]["format"] == "json"
+
+
+class TestRunEmbedSummaries:
+    class _EmbedConn:
+        def __init__(self, rows):
+            self._rows = rows
+            self.update_calls: list[tuple] = []
+
+        async def fetch(self, query, *params):
+            return self._rows
+
+        async def execute(self, query, *params):
+            self.update_calls.append(params)
+            return "UPDATE 1"
+
+        async def close(self):
+            pass
+
+    class _EmbedSession:
+        def __init__(self, dim=1024):
+            self._dim = dim
+
+        def post(self, url, json):
+            return _FakeEmbedResponseForEmbed({"embedding": [0.1] * self._dim})
+
+        async def close(self):
+            pass
+
+    def _patch(self, monkeypatch, conn, session=None):
+        async def _fake_connect(dsn):
+            return conn
+        monkeypatch.setattr("documents_ingest.summarize.asyncpg.connect", _fake_connect)
+        if session is not None:
+            monkeypatch.setattr("documents_ingest.summarize.aiohttp.ClientSession", lambda *a, **k: session)
+
+    async def test_dry_run_counts_without_writing(self, monkeypatch):
+        conn = self._EmbedConn(rows=[{"id": 1, "summary": "s"}])
+        self._patch(monkeypatch, conn)
+        stats = await run_embed_summaries(dsn="x", apply=False)
+        assert stats["summaries_fetched"] == 1
+        assert stats["embedded"] == 1
+        assert conn.update_calls == []
+
+    async def test_apply_embeds_and_updates(self, monkeypatch):
+        conn = self._EmbedConn(rows=[{"id": 1, "summary": "s"}])
+        session = self._EmbedSession()
+        self._patch(monkeypatch, conn, session)
+        stats = await run_embed_summaries(dsn="x", embed_model="bge-m3", apply=True)
+        assert stats["embedded"] == 1
+        assert stats["errors"] == 0
+        assert len(conn.update_calls) == 1
+        vector_literal, embed_model, summary_id = conn.update_calls[0]
+        assert embed_model == "bge-m3"
+        assert summary_id == 1
+
+    async def test_balance_invariant(self, monkeypatch):
+        conn = self._EmbedConn(rows=[{"id": 1, "summary": "s"}, {"id": 2, "summary": "t"}])
+        self._patch(monkeypatch, conn)
+        stats = await run_embed_summaries(dsn="x", apply=False)
+        assert stats["embedded"] + stats["errors"] == stats["summaries_fetched"]
+
+
+class _FakeEmbedResponseForEmbed:
+    def __init__(self, payload):
+        self._payload = payload
+
+    async def __aenter__(self):
+        return self
+
+    async def __aexit__(self, *exc):
+        return False
+
+    async def json(self):
+        return self._payload
+
+    def raise_for_status(self):
+        pass
diff --git a/services/kb-postgres/init/004_summaries.sql b/services/kb-postgres/init/004_summaries.sql
new file mode 100644
index 0000000..c82a2ca
--- /dev/null
+++ b/services/kb-postgres/init/004_summaries.sql
@@ -0,0 +1,23 @@
+-- KB spine: document_summary — summaries + tags per document, half-product of compilation
+-- Additive: does not modify 001_envelope.sql, 002_chunks.sql, or 003_chunk_model_key.sql.
+-- Version: 004 — document_summary (module 5, phase 3, plan §4)
+--
+-- 1:N to envelope by model: the same envelope can carry summaries from multiple models
+-- (pilot A/B: API vs local GPU); retrieval selects a model via config.
+
+CREATE TABLE IF NOT EXISTS document_summary (
+    id              BIGSERIAL   PRIMARY KEY,
+    envelope_id     TEXT        NOT NULL REFERENCES envelope(id) ON DELETE CASCADE,
+    summary         TEXT        NOT NULL,
+    tags            JSONB       NOT NULL DEFAULT '[]',
+    model           TEXT        NOT NULL,          -- model that WROTE the summary
+    embedding       VECTOR(1024),                  -- NULL until embedded
+    embedding_model TEXT,                          -- embedding model (bge-m3); NULL with embedding
+    created_at      TIMESTAMPTZ NOT NULL DEFAULT now(),
+    UNIQUE (envelope_id, model)
+);
+
+CREATE INDEX IF NOT EXISTS document_summary_envelope_idx
+    ON document_summary (envelope_id);
+CREATE INDEX IF NOT EXISTS document_summary_embedding_hnsw_idx
+    ON document_summary USING hnsw (embedding vector_cosine_ops);