UK Companies House Filing and Control Watch

Companies House filing history AND persons with significant control for the companies you name, in one cell: a new filing appearing, and a PSC being added, removed or having their nature of control change. PER-COMPANY SCOPE: the public service serves one company at a time, so this watches your list — it is not a whole-register feed. Filing documents are not opened or parsed.

    ## Source
    Companies House public company information service (public, logged-out)
    - https://find-and-update.company-information.service.gov.uk/company/{number}/filing-history

• https://find-and-update.company-information.service.gov.uk/company/{number}/persons-with-significant-control

  Public, logged-out only — no API key, login, cookie or CAPTCHA.
  
    ## Pricing
    | Event | Price (FREE tier) |
    |---|---|
    | Actor start (`apify-actor-start`) | $0.02 one-time |
    | Source check (`source-check`) | $0.10 |
  

| Per delta (company-delta) | $0.05 |

`source-check` ladder, GOLD-floored: **$0.10 / $0.09 / $0.08 / $0.067**, charged
    once per run after enumeration terminates — seed and genuine-zero runs included.
    The per-delta value event (`company-delta`) is the **primary** event and is priced at **$0.05 per delta** at the FREE tier. Ladder, GOLD-floored: **$0.05 / $0.045 / $0.04 / $0.0335** (FREE / BRONZE / SILVER / GOLD-PLATINUM-DIAMOND). `source-check` still charges; it is no longer the headline event. Billed deltas are capped at 500 per run and any overflow is reported as a withholding rather than charged.

    ## Snapshot mode is a PREVIEW
    `watch_mode: false` returns at most **25 records**, hard-capped in code regardless
    of `max_items`, labeled `output_mode: "preview"`. This cell sells change detection,
    not bulk record export.

    ## Watch semantics
    First watch run stores a private baseline and emits **zero** deltas. Later runs emit
    `NEW` / `CHANGED` / `REMOVED` keyed on the source-native id with `before` / `after`
    and `changed_fields`. A build whose signature shape changes RE-SEEDS rather than
    emitting a storm of deltas nobody caused.

    ## Source cadence
    Companies House publishes filings on business days. A newly accepted filing appears in the history immediately but its DOCUMENT can take days to process, which the cell handles explicitly — see the README note on filing keys.

    ## A note on filing keys you should know about

A filing appears in the history the moment Companies House accepts it, but its DOCUMENT can take days to process — the service says so on the row itself. During that window the row carries no transaction id. Measured live: 24 of 25 rows had an id and the one that did not was the newest filing.

Rather than drop it, this cell gives such a row a deterministic key built from its date, type and description, so a brand-new filing is reported immediately. When the document later lands, that filing's key becomes the official transaction id — which surfaces as a key change, not a silent substitution. If you reconcile on transaction_id, use document_available to tell the two states apart.

PSC entries carry no official identifier on the public page at all, so they are keyed on company number + normalised name + notified-on date. That is the strongest identity the public service offers, and a PSC renaming themselves will read as a removal plus an addition.

## Terminal states
    `NORMAL` · `SUCCEEDED-0: GENUINE_EMPTY` · `SUCCEEDED-0` (no change) · `PARTIAL` · `BLOCKED`.
    A zero with no evidence FAILS loud rather than exiting 0 quietly.