Contributor guidance: source findings log + PR/normalization requirements

AGENTS.md

@@ -22,6 +22,13 @@ So datasheets and the README narrative are **hand/contributor-maintained**.
 Never run `make_docs.py` and commit the result blind — `git diff` first and
 restore anything it dropped or restamped.
 
+## Before you start: check the findings log
+
+`artifacts/source_findings.md` records sources already investigated, including
+the rejected ones and *why*. Check it before spending a day on a source someone
+already found to be blocked — and append your own finding there whether the
+answer was yes or no.
+
 ## Add a source
 
 1. Produce the artifact under `data/<key>/`:
@@ -41,6 +48,82 @@ restore anything it dropped or restamped.
    text, positive token counts, uniform source/license, stats-file consistency).
    Run `python3 -m pytest src/` before committing.
 
+## What the PR must show
+
+These two are not optional — they are the difference between a source a reviewer
+can accept and one that sits in the queue. Treat every source PR as a worked
+example other contributors will copy.
+
+1. **A sample of the data, inline in the PR description.** A few real documents
+   (or truncated ones), verbatim, so a reviewer can see at a glance what kind of
+   text this actually is — prose, transcripts, boilerplate, OCR noise, HTML
+   leftovers. Include the metadata columns too, not just `text`. Don't make the
+   reviewer download a parquet to find out.
+
+2. **Provenance and licensing, written out in the datasheet (`data/<key>/<key>.md`)
+   and summarized in the PR description:**
+   - Where the data comes from — the concrete origin (institution, portal, API,
+     dump), not just a domain name. Link it.
+   - Under what license, and **where that license statement lives** — link the
+     exact terms-of-use page, API docs section, or statute. "Public domain
+     because it's government data" is a claim, not a source; cite the provision.
+   - What the texts are — genre, register, time span, language variety, whether
+     they are OCR'd, machine-translated, or user-generated.
+   - How it was collected and filtered — dedup, minimum length, language ID,
+     anything dropped and why.
+   - The argument for inclusion — what this adds that the corpus does not
+     already have, and any known bias or quality caveat a downstream user should
+     weigh.
+
+Yes, this is meta work on top of the fetching. That is the point: the datasheet
+is the artifact other people read to learn how to contribute well.
+
+## Normalize the text before you build
+
+`build_dynaword.py` applies only *minimal gates* — strip, `len < 200`, Polish
+diacritic ratio, OCR alpha ratio, exact sha1 dedup. It does **not** clean text.
+`src/normalize_schema.py` is a schema/stats tool despite the name; it never
+touches `text`. So normalization is the fetcher's job, and today each fetcher
+reimplements it (`fetch_govpl.py:43` and `fetch_saos.py:42` carry byte-identical
+`html_to_text`; `clean_samorzad_gov_pl.py:65` a third variant). If you are
+writing a new fetcher, factor the shared parts out rather than pasting a fourth
+copy.
+
+What a fetcher should do to `text` before writing the `.jsonl.zst`:
+
+- **Unicode**: NFKC normalize. Map non-breaking/thin/zero-width spaces to plain
+  space (or drop), strip control characters and soft hyphens, normalize the
+  quote/dash/ellipsis zoo. Repair mojibake if the upstream encoding is unreliable.
+- **Whitespace**: collapse runs of spaces/tabs, trim per line, cap blank runs at
+  one empty line. Do not flatten paragraph breaks — they carry structure.
+- **Structural junk**: navigation, cookie banners, "share this", pagination,
+  footnote back-references, and — for OCR/PDF sources — page headers/footers,
+  running titles, and hyphenation split across line breaks.
+- **Numbering**: strip standalone chapter/section/page numbers and repeated
+  heading numerals (`1.`, `Art. 5.`, `Rozdział III`) *only where they are layout
+  artifacts*. In `dziennik_ustaw` or `saos` the article numbering is content —
+  removing it destroys the document. Judge per source, and say what you did in
+  the datasheet.
+- **Boilerplate**: near-identical blocks repeated across most documents of a
+  source (license footers, institutional disclaimers, "Pokaż odpowiedź"-style UI
+  chrome) should be detected by frequency across the shard and removed, not
+  hand-listed.
+- **Personal data**: scrub before the parquet is written, not after. At minimum
+  email addresses, phone numbers, and national identifiers (PESEL, NIP, REGON,
+  account numbers). Replace with a stable placeholder (`[PII]`, `[Telefon]`)
+  rather than deleting, so sentence structure survives. Names of public
+  officials acting in an official capacity are not PII and should stay —
+  removing them would gut parliamentary and judicial sources.
+
+Two rules about all of the above:
+
+1. **The normalization must live in the committed fetch/clean script**, so the
+   shard is reproducible. A shard whose datasheet describes a cleaning step that
+   no script in `src/` performs is not reproducible, however good the intent.
+2. **Report it in the datasheet**: which steps ran, and what the gates dropped.
+   Include a handful of before/after excerpts in the PR — this is the fastest way
+   for a reviewer to see whether normalization ate real content.
+
 ## Cut the release (the part that gets skipped)
 
 1. In `src/make_docs.py`: bump `VERSION` and `RELEASE_DATE`. Add a row for the new

artifacts/source_findings.md

@@ -0,0 +1,543 @@
+# Source investigation findings
+
+Running log of sources that were investigated, whether or not they were added.
+**Append-only, version-independent** — unlike the `*_v0_3.md` artifacts, which are
+point-in-time snapshots of one release's candidate review.
+
+Purpose: stop the same source being re-investigated from scratch every few months.
+A negative finding is as valuable as a positive one, as long as it records *what
+was checked* and *what would change the answer*.
+
+Related, don't duplicate:
+- `source_scouting_v0_3.md` — v0.3 candidate shortlist (HuggingFace-centric)
+- `source_candidate_audit_v0_3.md` — machine-generated audit of those HF cards
+- `source_license_review_v0_3.md` — v0.3 license decision table
+
+## How to add an entry
+
+One `##` section per source. Keep these fields:
+
+- **Investigated** — date, so a stale finding is visible as stale.
+- **Verdict** — `added` / `blocked` / `hold` / `rejected`, plus the one-line reason.
+- **Enumeration** — how you would actually get the data, or why you can't.
+- **License evidence** — what you checked, with URLs. Separate what you *verified
+  yourself* from what you read second-hand; label the weak ones.
+- **Blockers** — what must be resolved before this can ship.
+- **Lesson** — anything generalizable to other sources. Optional.
+
+Write down the API endpoints and quirks you had to dig for. That digging is the
+expensive part, and it is invisible in a verdict line.
+
+---
+
+## zpe.gov.pl — Zintegrowana Platforma Edukacyjna
+
+**Investigated:** 2026-08-27
+**Verdict:** `hold` — technically very tractable, blocked on per-material license
+evidence. Do not build a fetcher until the license question below is answered.
+
+Ministry of Education platform (successor to `epodreczniki.pl`), e-materials
+across all school subjects. Attractive because the corpus has **no modern
+instructional/pedagogic register at all**, and this is contemporary, clean,
+editorially reviewed Polish prose.
+
+### Enumeration — solved
+
+There is no sitemap (`/sitemap.xml` → 404) and site search is client-side, but
+`https://zpe.gov.pl/config.js` exposes an undocumented JSON API:
+
+```
+window.CP_CONFIGURATION = {... "apiUrl":"https://zpe.gov.pl/api/v1/" ...}
+```
+
+```
+GET https://zpe.gov.pl/api/v1/search?query=&limit=20&offset=N
+→ {"count": 23843, "offset": 0, "limit": 20,
+   "data": [{"id": "P18l4AKOi", "title": "Fotosynteza",
+             "subject": [...], "stage": [...], "tags": [], ...}]}
+```
+
+Verified directly (2026-08-27):
+
+- `count` = **23,843** materials for the empty query.
+- Deep paging works — `offset=5000` returns rows, no cursor needed.
+- `robots.txt` is `User-agent: * / Allow: /`.
+- Article pages `/a/<slug>/<CODE>` are **fully server-rendered**; text lives in
+  `data-editor-content` blocks. No JS execution required to extract prose.
+- Book pages `/b/<slug>/<CODE>` render their material list client-side (0
+  server-side `/a/` links), so `/b/` is useless for crawling. Use the API.
+
+Other endpoints probed and 404: `api/v1/materials`, `api/v1/document(s)/<CODE>`,
+`api/v1/footer`, `api/v1/menu`, `api/v1/search/materials`. Only
+`api/v1/search?query=` responded.
+
+### License evidence — the blocker
+
+**Verified directly:**
+
+- **No document-level license marker exists in the served HTML.** The only
+  machine-readable license strings are per-figure, inside
+  `<div class="figure_caption_bibliography">`, e.g.
+  `Źródło: GroMar, licencja: CC BY 3.0.` and
+  `Źródło: Sławomir Szaruga, licencja: CC BY 3.0.` These attach to
+  **illustrations, not to the prose**.
+- **The site footer is `<div id="footer_app"></div>` — JS-rendered.** This
+  matters: the accepted legal basis for both `govpl` and `samorzad_gov_pl` in
+  `src/sources.py` is a *server-side footer string* declaring CC BY-SA 4.0.
+  ZPE has no such string. **That precedent does not transfer to ZPE.**
+- The platform `regulamin` states:
+  *"Korzystanie z Materiału odbywać się może tylko i wyłącznie w zakresie
+  dozwolonym przepisami ustawy o prawie autorskim i prawach pokrewnych"* —
+  statutory permitted-use only, which is not an open license. Reading the
+  surrounding clauses, this section appears scoped to material *uploaded by
+  users to* the platform rather than to ministry e-materials, but the wording is
+  not self-limiting and a reviewer will land on it.
+
+**Second-hand, not verified — confirm before relying on any of it:**
+
+- Ministry-produced e-materials are said to be CC BY 3.0, funded under
+  POKL 2007–2013 / POWER 2014–2020.
+- User-contributed materials are reported to carry **CC BY-NC-SA 4.0**. NC is
+  already on the reject list (`source_scouting_v0_3.md`), so those must be
+  excluded, not merely flagged.
+- Literary works embedded in e-materials are reported to sit under a
+  non-free *"licencja edukacyjna"* where authors or heirs did not agree to open
+  release. This is the highest-risk content class on the platform.
+
+### Consequences for design
+
+- ZPE cannot be a single-license shard. It has to be **per-record license-gated**,
+  `license_spdx: MIXED`, same shape as `biblioteka_nauki` and `europeana`.
+- Available heuristic, **not** license evidence: ministry materials come back with
+  `subject` and `stage` populated; user uploads return `"subject": [], "stage": []`
+  (the first empty-query result is an all-caps user upload with both empty). Usable
+  as a pre-filter, useless as provenance.
+- Rough size if ~10–15k ministry materials survive the gate: **~30–100M tokens**.
+  Estimate only — nothing was counted. Good register, modest scale.
+
+### Extraction hazards (seen in a single sampled page)
+
+- Interactive-exercise chrome: `Pokaż podpowiedź`, `Pokaż odpowiedź` buttons.
+- JSON blobs embedded in `data-editor-params` attributes (`gameTitle`,
+  `feedbackPositive`, …) — must not leak into `text`.
+- Per-figure attribution lines repeated throughout the body.
+- Glossary / `Zapamiętaj!` boilerplate repeated across many materials — needs
+  frequency-based boilerplate detection, not a hand-written blocklist.
+
+### What would unblock this
+
+Any one of: a resolvable per-material license field (API or page markup); an
+authoritative ORE/MEN page granting open reuse of e-material *text*; or written
+permission. Absent that, ZPE stays out — the datasheet could not honestly answer
+"where does the license statement live", which is a required field for any PR.
+
+### Lesson
+
+Check for a **server-rendered** license statement early. A JS-rendered footer is
+not usable license evidence, and "it's a `gov.pl` domain" is not a license — the
+`govpl` and `samorzad_gov_pl` entries hold up because a specific footer string
+was fetched and quoted, not because of the domain.
+
+---
+
+## ParlaMint-PL — parliamentary debates 2015–2022
+
+**Investigated:** 2026-08-27
+**Verdict:** `ready to build, low yield` — license and distribution verified, the
+fetcher is the only missing piece. But it is a **date-hole patch worth ~36M
+net-new tokens**, not a diversity win. Size it before prioritising it.
+
+Already registered in `src/sources.py` as `parlamint_pl`, but there is **no shard
+in `data/`**.
+
+### Size — measured, not guessed
+
+From the official stats at
+`github.com/clarin-eric/ParlaMint/tree/v5.0/Build/Metadata`
+(`ParlaMint-overview-stats.tsv`, `ParlaMint-speeches-stats.tsv`):
+
+```
+ID  Lang  Bodies   Ts  From     To       Yrs  Mw/Yr  Mw
+PL  pl    low+upp  4   2015-11  2022-06  6.7  5.35   36.06
+```
+
+- **36.06M words**, **228,326 speeches**, 4 terms, both chambers.
+- Token conversion measured on our own `parliamentary` shard (same register, same
+  cl100k encoder; 6,000 docs / 9.7M words): **2.654 tokens/word**, 7.24 chars/word.
+- → **~96M tokens gross**, ≈1% of the current 9.68B corpus.
+- Download: `ParlaMint-PL.tgz`, 185.3 MB.
+
+### Overlap with the existing `parliamentary` shard — the real issue
+
+ParlaMint-PL is **derived from PPC**, which is exactly what the `parliamentary`
+shard is (1991–2019). Time overlap runs 2015-11 → 2019-12, about 4.2 of the 6.7
+years, ≈22M words likely already present. **Net new ≈ 14M words ≈ 36M tokens**,
+covering 2020-01 → 2022-06.
+
+That estimate is soft in both directions:
+
+- `parliamentary` has **no per-document dates** — `created` is the single literal
+  `'1991-01-01, 2019-12-31'` on all 324,622 rows. The overlap cannot be measured
+  by filtering, only by comparing content.
+- PPC includes committee sittings and interpellations; ParlaMint-PL is plenary
+  only. So ParlaMint's 2015–2019 portion is plausibly a *subset* of what already
+  ships, making the real overlap higher than the time-share implies.
+
+**Exact dedup will not catch this.** `build_dynaword.py` dedups on `sha1` of the
+whole document. ParlaMint ships one document per session; PPC's segmentation
+differs, so byte-identical documents are unlikely and the duplicates pass
+straight through the gate. This needs **near-dedup, for which the repo has no
+committed tooling** — the HPLT expansion's near-dedup was run outside `src/`.
+Budget for that, or the shard silently duplicates existing data.
+
+### Version note
+
+**ParlaMint 5.0 does not extend Polish** — PL still ends 2022-06, same as the 3.0
+deposit already cited in `sources.py` (handle `11356/1486`; 5.0 is `11356/2004`).
+Upgrading buys corrections, not coverage. Neither version closes the gap to
+`sejm_api` (2023 onward): mid-2022 through end-2022 stays empty.
+
+### Verified
+
+- CLARIN.SI handle `11356/1486` resolves (HTTP 200). The `upstream` URL recorded
+  in `sources.py` is correct and live.
+- License: **CC BY 4.0**, stated on the repository record.
+- ParlaMint 3.0 overall: 26 comparable corpora, 7,468,674 utterances,
+  1,147,800,265 words; debates mostly 2015 → mid-2022.
+- The distribution ships a **plain-text (`.txt`) edition** alongside TEI/XML and
+  linguistically-annotated `.ana.xml`. Filenames are per-session, e.g.
+  `ParlaMint-PL_2017-07-20-sejm-46-3.txt`. Use the `.txt` edition — no TEI parsing
+  needed.
+- Polish covers **both chambers**: `-sejm-` and `-senat-` session files.
+
+### Why it is still worth doing
+
+Fills 2020 → mid-2022, between `parliamentary` (ends 2019) and `sejm_api` (2023
+onward). Same CC-BY-4.0 family as existing sources, so there is no new license
+question to answer, and the plain-text edition means no TEI parsing. Cheap. Just
+do not expect it to move the totals — and do not build it before a source that
+adds a register the corpus lacks.
+
+### Drift found while checking
+
+`src/sources.py` (the `parlamint_pl` `provenance` field) states the corpus was
+*"Fetched directly from the CLARIN.SI plain-text edition (ParlaMint-PL.tgz) by
+`src/fetch_parlamint.py`"*. **That script does not exist in `src/`.** The
+provenance describes a fetch that no committed code performs. Either write the
+script or correct the field before this ships.
+
+---
+
+## Sejm API — interpelacje and zapytania poselskie
+
+**Investigated:** 2026-08-27
+**Verdict:** `hold — recheck`. Not a license problem; `api.sejm.gov.pl` was
+unreachable from the investigating network on the day, so the endpoints could not
+be confirmed. Retry before writing anything off.
+
+### What happened
+
+- `api.sejm.gov.pl` resolves (`194.41.12.231`) but every request hangs and then
+  fails — plain `curl` times out at 45s, a proxied fetch returns `ECONNRESET`.
+- `https://www.sejm.gov.pl/` responds normally (302), and other external hosts
+  were fine the same session, so this is specific to the API host: either an
+  outage, or that host filtering the source network.
+- `src/fetch_sejm_api.py` (committed, working) uses this same host, so the API
+  is normally reachable. Treat as transient until proven otherwise.
+
+### Unverified — what to check on retry
+
+- Whether `sejm/term{N}/interpellations` and `sejm/term{N}/writtenQuestions`
+  exist, and their paging parameters.
+- Whether the **ministry's reply body** is retrievable as text, or only as a
+  linked PDF. This decides whether the source is worth building: the replies are
+  the substantial half.
+- Document counts per term.
+
+### Why it is on the list
+
+Reuses the existing `fetch_sejm_api.py` legal basis unchanged — official
+parliamentary materials outside copyright under art. 4(2) pr. aut., reusable
+under the Open Data Act. Question/answer prose is argumentative register, which
+the corpus is short on. No new license work needed.
+
+---
+
+## CLARIN-PL DSpace (PELCRA Spokes, and the `1000_novels` upstream)
+
+**Investigated:** 2026-08-27
+**Verdict:** `blocked — temporary`. The repository is down for reorganization.
+Nothing to decide until it returns.
+
+### Verified
+
+- `https://clarin-pl.eu/dspace/` serves a maintenance notice:
+  *"Trwają prace nad repozytorium. Prowadzimy prace serwisowe oraz reorganizację
+  repozytorium DSpace… Repozytorium będzie ponownie dostępne wkrótce."*
+- Every item handle under it 404s: `11321/312`, `11321/544`, `11321/545`,
+  `11321/547` — nginx 404, not a DSpace "item not found".
+- The global resolver is broken for this prefix too: `hdl.handle.net/11321/*`
+  returns **HTTP 500**.
+
+So no PELCRA record (Spokes, EMO, PARL, EMI) can have its license checked right
+now. Conversational Polish remains the corpus's biggest register gap, so this is
+worth re-checking periodically.
+
+### Side effect on shipped data
+
+`src/sources.py` records `https://clarin-pl.eu/dspace/handle/11321/312` as the
+`upstream` for **`1000_novels`**, which is a released shard. That URL currently
+does not resolve. Presumed temporary, but the citation in a published datasheet
+is dead as of this date.
+
+### Expected concern when it returns
+
+PELCRA spoken corpora are transcribed private conversation. Expect NC-flavoured
+or restricted licensing, and expect a personal-data question — these recordings
+involve identifiable private individuals, not public officials acting officially.
+Both must be resolved before use.
+
+---
+
+## NIK — Najwyższa Izba Kontroli audit reports
+
+**Investigated:** 2026-08-27
+**Verdict:** `hold` — permissive but **non-standard** license, and enumeration is
+unsolved. Viable with work; not a quick win.
+
+### License evidence — verified
+
+`https://www.nik.gov.pl/zasady/prawa-autorskie.html` states:
+
+> *"Korzystanie z materiałów publikowanych w serwisach internetowych Najwyższej
+> Izby Kontroli nie wymaga uzyskania zgody NIK. Nie dotyczy to elementów odrębnie
+> zastrzeżonych (do których prawa autorskie przysługują osobom trzecim), w
+> szczególności oznaczonych materiałów zdjęciowych oraz tekstów publikowanych
+> pierwotnie w innych źródłach."*
+
+Attribution to *"Najwyższa Izba Kontroli (nik.gov.pl)"* is requested, not required.
+
+Assessment: a **custom permissive notice, not a standard open license** — no CC,
+no CC0, no SPDX identifier. It carries a third-party carve-out that matters here,
+because audit reports quote external sources. A separate and probably stronger
+argument is that audit reports are *materiały urzędowe* under art. 4 pkt 2 pr.
+aut., the same basis as `dziennik_ustaw` and `sejm_api`. If this source is built,
+lead with the statutory argument and cite the site notice as corroboration.
+
+### Enumeration — unsolved
+
+- `robots.txt` allows crawling, but disallows `/szukaj/`, `/p/`, `/g2/`,
+  `/cms/`, `/do_druku/`. `/g2/` looks like the file store, which likely means
+  **report PDFs are off-limits to crawlers**.
+- `/kontrole/wyniki-kontroli-nik/` returns 200 (~72 kB) but the report list is
+  **JS-rendered**: zero report links in the server HTML, only pagination
+  scaffolding (`fmax,js,strona,1.html`).
+- The `/prosta/` ("simple") variant is also JS-rendered — 0 report links.
+- No `/sitemap.xml` (404).
+
+Same shape as ZPE: a backend API almost certainly exists and would need to be
+found (check the page's JS config for an `apiUrl`, as worked for ZPE).
+
+### Verdict rationale
+
+Register value is real — long-form analytical prose, unlike statute text. But
+between a bespoke license, a third-party-content carve-out, PDF paths blocked by
+`robots.txt`, and unsolved enumeration, this is several days of work. Lower
+priority than ParlaMint-PL or Sejm interpelacje.
+
+---
+
+## Billion-scale survey — what can actually move the totals
+
+**Investigated:** 2026-08-27
+
+Context: most candidates land at 30–200M tokens, which is noise against a 9.68B
+corpus. This entry records the only options measured at **500M–5B**, i.e.
+comparable to `european_hplt_v3_pl` (2.56B), `eurlex` (2.38B), `parliamentary`
+(1.65B). All numbers below were measured on the day, not taken from cards.
+
+Token conversion throughout: **2.654 tokens/word**, measured on the repo's own
+`parliamentary` shard (6,000 docs / 9.7M words, cl100k). Use it instead of
+guessing — Polish runs far above the ~1.3 rule of thumb for English.
+
+| candidate | measured | est. tokens | license | blocker |
+|---|---|---|---|---|
+| SAOS judgments | 540,338 docs, mean 3,067 w | **~4.4B** (floor ~2.8B) | art. 4 pkt 2 pr. aut. | register: pure legal |
+| FineWeb-2 `pol_Latn` | 152,003,298 docs, 225.9 GB | ~83B raw, **4–8B** filtered | ODC-By | dedup vs existing HPLT |
+| PleIAs/Polish-PD | 68,176 docs, 0.75B words | **~2.0B** nominal | public domain | OCR corruption |
+| HPLT leftovers | shards `8_5`, `8_6`, 31.6 GB | ~230M | CC0 | none — just small |
+
+### SAOS — biggest clean win, already half-built
+
+`https://www.saos.org.pl/api/search/judgments?pageSize=1&pageNumber=0` reports
+`totalResults: 540338`. Sampled 100 judgments from
+`api/dump/judgments?pageSize=100&pageNumber=0`: **mean 3,067 words, median 1,920,
+p10 816, p90 7,197**, court types `COMMON` and `CONSTITUTIONAL_TRIBUNAL`.
+
+540,338 × 3,067 = 1.66B words → **~4.4B tokens**. Using the median instead, to
+guard against long-tail skew, still gives ~2.75B. Either way this is **larger
+than any shard currently in the corpus**.
+
+`src/fetch_saos.py` already exists (uncommitted as of this date) and documents the
+legal basis: judgments are *materiały urzędowe* outside copyright under art. 4
+pkt 2 pr. aut., redistributed by SAOS (CeON/ICM UW + Fundacja ePaństwo) through a
+bulk-dump API built for exactly this.
+
+Open question before building: judgments are court-anonymised, but that should be
+**verified on sampled text**, not assumed — this is the one candidate here where
+personal data is a live risk rather than a formality.
+
+Cost of shipping it: legal/official goes from **48% to roughly 65%** of the
+corpus. That is the trade, and it should be a deliberate decision rather than a
+side effect of it being the easy build.
+
+### FineWeb-2 Polish — only billion-scale contemporary prose
+
+`datasets-server` size endpoint, config `pol_Latn`: **152,003,298 rows /
+225.9 GB**. At the measured 0.367 tokens/char that is **~83B tokens raw**.
+
+License `odc-by`. Same argument shape as the accepted HPLT basis: the packaging
+is licensed, the underlying web text is not owned by the publisher. Note that
+ODC-By is **attribution-required**, unlike HPLT's CC0 — a different obligation
+shape, and it has to be stated in the datasheet.
+
+#### Dedup is not the bottleneck — this was checked, not assumed
+
+The obvious worry is overlap with the existing HPLT shard, since both derive from
+Common Crawl. It is the *smallest* of the problems:
+
+- The existing HPLT shard is **1.6M docs against FineWeb-2's 152M**. Even total
+  overlap removes ~1% of candidates (~12% if working from the HQ subset below).
+- **Internal dedup is already done upstream.** The schema carries
+  `minhash_cluster_size`, i.e. FineWeb-2 ran MinHash per language before release.
+
+Cross-dedup against HPLT is still worth doing for hygiene, and the repo still has
+no committed near-dedup tooling — but it is not what makes this source expensive.
+
+#### The actual blocker: the HPLT gate cannot be ported
+
+FineWeb-2 `pol_Latn` columns are:
+
+```
+text, id, dump, url, date, file_path, language,
+language_score, language_script, minhash_cluster_size, top_langs
+```
+
+`src/clean_hplt_v3.py` filters on **WDS quality score, register class
+(ID/OP/HI/IN/NA), and MT-probability**. *None of those exist in FineWeb-2.* Every
+signal the existing web pipeline depends on is absent, so "filter it like we
+filtered HPLT" is not an option — it would mean building quality classification
+over 152M documents from scratch.
+
+#### `epfml/FineWeb2-HQ` — the better target
+
+A published quality-filtered derivative, config `pol_Latn`:
+
+- **13,384,885 rows**, `odc-by`, 180.4 GB parquet (size dominated by an
+  `embeddings` column, not text).
+- Adds a **`quality_score`** column, retained per document, so the selection
+  threshold stays a tunable knob instead of a baked-in decision — and the
+  classifier is someone else's published work, which is easier to cite than a
+  home-grown one.
+- Sampled 880 docs across 22 evenly-spread offsets: **mean 2,663 chars/doc**
+  → ~13.1B tokens for the whole HQ subset. Larger than the entire current corpus.
+
+#### quality_score → token yield
+
+Distribution from the `statistics` endpoint (computed on a **partial 407,184-row
+sample**, not all 13.4M): min 0.013, max 0.9999, mean 0.145, **median 0.0496** —
+heavily right-skewed, so most of HQ still scores low.
+
+Doc fractions from that histogram, mean lengths from the 880-doc sample:
+
+| `quality_score` ≥ | % docs | docs | mean chars | est. tokens |
+|---|---:|---:|---:|---:|
+| 0.00 (all) | 100% | 13,384,885 | 2,663 | **13.1B** |
+| 0.11 | 31.0% | 4,149,000 | 2,375 | **3.6B** |
+| 0.21 | 20.0% | 2,677,000 | 2,074 | **2.0B** |
+| 0.31 | 14.6% | 1,954,000 | 1,929 | **1.4B** |
+| 0.41 | 11.1% | 1,486,000 | 1,912 | **1.0B** |
+| 0.51 | 8.5% | 1,138,000 | 1,798 | **0.75B** |
+| 0.70 | 4.8% | 642,000 | 1,750 | **0.41B** |
+| 0.90 | 1.8% | 241,000 | 914 | **0.08B** |
+
+A second pass computing fractions directly from the 880-doc sample agreed with
+these within ~15%. Treat them as ±20%, good enough to pick a threshold.
+
+**Watch out: `quality_score` anti-correlates with document length.** Mean length
+falls from 2,663 chars at no threshold to 914 at ≥0.90. The classifier is not
+rewarding long-form prose, so raising the threshold costs more tokens than the
+doc-count alone implies, and it may actively select *against* the extended prose
+this corpus is short on. Sample the text at whatever threshold is chosen before
+committing to it.
+
+#### Recommended operating point
+
+**Threshold ≈ 0.20 → ~2.7M docs, ~2.0–2.3B tokens.** Comparable to the largest
+existing shards (`european_hplt_v3_pl` 2.56B, `eurlex` 2.38B) and it *improves*
+the balance rather than wrecking it: web goes 26% → ~41%, legal drops 48% → ~39%.
+
+Taking all 13.1B instead would put the corpus at ~22.7B with **web at ~69%** —
+trading "two-thirds legalese" for "two-thirds crawl". Same failure, different axis.
+
+#### Work order if this is built
+
+1. Pick HQ vs full, and a `quality_score` threshold (see above).
+2. **Build the PII scrub.** `sources.py` already claims one for the HPLT shard
+   that has no implementing code in `src/`; shipping a second web source with the
+   same gap is indefensible.
+3. Near-dedup against the existing HPLT shard — needed, but ~1–12% effect.
+4. Compute. Tokenizing billions of tokens is the genuinely expensive step.
+
+### PleIAs/Polish-PD — good on paper, rough in practice
+
+68,176 rows. Sampled `word_count` at four offsets (n=200): **mean 10,971 words,
+median 8,468** → ~0.75B words → **~2.0B tokens**. Columns are `identifier`,
+`file`, `title`, `creator`, `language`, `word_count`, `character_count`,
+`complete_text`. Public domain, pre-1884 monographs and periodicals, largely
+sourced from Polish digital libraries (`jbc.bj.uj.edu.pl` in the sample).
+
+Register-wise this is the most attractive of the three — books and periodicals,
+against a corpus that is only 1.9% literature.
+
+But the OCR is bad. First sampled record (an 1817 newspaper) opens:
+
+```
+U
+RUSKI
+czwaRTEŁ SONAER
+5 PC Nę R
+WIADOMOŚC
+```
+
+with pre-1884 orthography throughout (`Nayiaśnieyszy`, `roskazać`, `klassy`).
+
+**The existing OCR gate will not catch this.** `build_dynaword.py` applies
+`MIN_ALPHA_RATIO = 0.70` when `is_ocr: True`, which tests the ratio of letters to
+symbols. Garbled *words* made of ordinary letters pass it cleanly. Filtering this
+source needs a dictionary- or perplexity-based check, which does not exist here.
+Treat the 2.0B as nominal; real usable yield is materially lower.
+
+### HPLT is exhausted — correction to an earlier assumption
+
+`https://data.hplt-project.org/three/sorted/pol_Latn/` lists **exactly 19 shards**:
+`10_1`, `9_1`–`9_4`, `8_1`–`8_6`, `7_1`–`7_4`, `6_1`–`6_2`, `5_1`–`5_2`.
+**There are no WDS bins below 5 for Polish.**
+
+`sources.py` records 17 of those as ingested. The only unused shards are
+**`8_5` (24.24 GB)** and **`8_6` (7.37 GB)** — roughly 230M tokens at the
+post-filter rate implied by the existing shard.
+
+So "add more HPLT bins" is not a path to billions. It is one small top-up, and
+then the source is finished.
+
+### Conclusion
+
+Every clean billion-scale Polish source is **legal, official, or archaic** —
+which follows directly from what falls outside copyright. The only billion-scale
+contemporary general prose is web crawl, and that is a re-derivation of Common
+Crawl the corpus already draws on.
+
+If the goal is raw scale: SAOS. If the goal is a corpus that is not two-thirds
+legalese, **there is no billion-scale option**, and the honest plan is a number of
+50–200M-token sources across different registers.