docs(scripts): reconcile renderCountsFile's docblock with the merge guidance it emits (#19006)

Fixes #18960

Clause-②: no

`renderCountsFile()`'s docblock said `merge=os-regen` was "the right
resolution" for
`docs/audits/2026-08-tenant-audit-write-call-sites.counts.md`, "the same
as its
strictness-ledger sibling". The header that the same function emits into
that file says
the opposite. One of the two had to be wrong; measurement says the
docblock was.

Prose only. No behaviour change, no `.gitattributes` change, no
`.counts.md` change.

## The measurement that decides it

`git check-attr merge`, run in this worktree with a **lit control** (the
sibling the
docblock itself named) and a **dark control** (a path that does not
exist) — because the
object and the dark control read the same value, so `unspecified` alone
cannot tell a real
absence from a dead instrument. The lit control is what separates them.

Before the edit, at base `2767af8e83`:

| path | `merge` | role |
|---|---|---|
| `docs/audits/2026-08-tenant-audit-write-call-sites.counts.md` |
`unspecified` | object |
| `docs/audits/2026-07-unknown-key-strictness-ledger.counts.md` |
`os-regen` | lit control — fires, instrument alive |
| `docs/audits/totally-fabricated-xyz.counts.md` | `unspecified` | dark
control |

After the edit, same three paths, same three values — this PR does not
touch attributes.

So the parity claim was false by exactly the comparison it named, and
the emitted header
was the accurate side.

## The docblock as it now reads

```js
/**
 * The audit ledger: every site, regenerated WHOLE.
 *
 * No prose to preserve, so nothing here is spliced -- the file is rewritten. Two
 * branches that each add a write call site produce rows that git merges cleanly and
 * a header that merges cleanly and WRONG, so the correct resolution is always
 * "recompute from the merged tree" -- `node scripts/tenant-audit-census.mjs --write`,
 * which is what the header this function emits tells a merging author to do.
 *
 * That resolution is not delegated to a merge driver: no `.gitattributes` entry
 * covers this path, so `git check-attr merge` over it reads `unspecified` and git
 * text-merges it like any other file. `scripts/check-tenant-audit-census.mjs` is the
 * backstop -- a wrongly merged file fails the build loudly instead of landing
 * silently.
 */
```

No assertion is left that this counts file is, or ought to be,
`merge=os-regen` — the
parity wording included. The two claims the card named as true and
load-bearing are kept,
and both still agree with the emitted header:

1. **regenerated whole, no prose to preserve, the file is rewritten** —
the emitted header
   says the same thing;
2. **two branches each adding a write call site merge rows cleanly and a
header cleanly
and WRONG, so the correct resolution is always to recompute from the
merged tree** —
the emitted header says the same thing, and now the docblock names the
command it
   prescribes.

What replaced the false sentence is a *measured* statement (no covering
entry, so
`check-attr` reads `unspecified`) plus the backstop the emitted header
already points at.
It deliberately does **not** restate the emitted header's *rationale*
for the absence —
see the acceptance note below.

## What this PR does not touch

- `.gitattributes` — this card is not "add a missing `os-regen`
registration". Registering
  this path is the wrong action the false sentence was inviting.
- The prose the function emits into the generated file
(`out.push(...)`).
- Any `.counts.md`, and any census verdict, `out.push` line, or
  `scripts/check-tenant-audit-census.mjs`.
- Whether the two `.counts.md` siblings ought to merge the same way. The
card names that as
  a separate question and this PR does not answer it.

## Verification

- **Behaviour dark leg** — `node scripts/tenant-audit-census.mjs
--write` run before the
edit and again after it, both at the same HEAD so the generator's
measurement stamp is a
  constant. Output byte-identical across the two runs:
  `4851056362eb1b196acef0dac60dee1cbddc2870` for the counts file and
`084932491a2b68a856880b68086f485ca58aaf3b` for
`tenant-audit-census.mdx`, both runs. The
artefacts were then restored to their committed bytes, so this PR's diff
is one file.
- `node scripts/check-tenant-audit-census.mjs --self-test` — exit 0
before and after
  (44 + 24 cases).
- `node scripts/check-tenant-audit-census.mjs` — exit 0 before and
after, 225 write call
  sites certified, 23 prose figures held to the census.
- Gate families derived with `node scripts/pm/dispatch-gates.mjs
--commands --repo
objectstack-ai/objectstack` against the real change set (1 path): **28
commands, all run,
all exit 0**; reconciled with `--ran` recording each exit code — "28
derived, 28 run,
  0 NOT-MEASURED, 0 UNRUN", a derived zero.
- **Changeset: `skip-changeset`.** Measured per file rather than
asserted: every non-private
manifest in the tree (70) was read and each diff path tested against its
`files[]`.
`scripts/tenant-audit-census.mjs` lands on none — it is root-level
tooling, and a `files[]`
entry is package-relative. Positive controls through the same predicate
fire:
`packages/spec/dist/index.js` hits `@objectstack/spec files[] "dist"`
and
`packages/cli/dist/cli.js` hits `@objectstack/cli files[] "dist"`.
Nothing published moves,
  and the change is a comment.

## Acceptance notes

**Noted, not filed here — the emitted header's stated *reason* for the
absence looks stale.**
The header this function emits says the file is not `merge=os-regen`
because "that driver
resolves an artefact's `gen:`/`check:` scripts in `@objectstack/spec`
only, and these are
root-level tooling". Two readings in this tree point the other way:
`scripts/git-merge-regen.mjs`
documents at `reconcileScripts()` that resolution reads "the owner's
manifest, whichever that
is" since #13585 — root included, `manifestFor('.')` being
`package.json` — and `.gitattributes`
already routes root-owned artefacts such as
`scripts/platform-object-tenancy-census.json` and
`docs/protocol-upgrade-guide.md` to `merge=os-regen`. That is about the
*reason*, not about the
*fact*: the absence itself is measured above and is not in doubt, and
whether this path ought to
be registered stays the separate question the card excludes. It is out
of scope here — the card
fences the emitted prose as read-only — so this PR states only what it
measured and leaves the
rationale to whoever takes that question. Reported to the dispatching
seat in the round report.

Out of scope: #18944, a separate card on this same file (the census's
engine-door
classification rule); deliberately not combined, per triage.

---
_Generated by [Claude
Code](https://claude.ai/code/session_01JbZnqu8bt6YqfJsr9vaFb3)_

Co-authored-by: Claude <noreply@anthropic.com>

Author: os-bill

scripts/tenant-audit-census.mjs

@@ -1562,11 +1562,17 @@ export function renderGeneratedRegion(census) {
 /**
  * The audit ledger: every site, regenerated WHOLE.
  *
- * No prose to preserve, so nothing here is spliced -- the file is rewritten. That
- * is what makes `merge=os-regen` the right resolution for it, the same as its
- * strictness-ledger sibling: two branches that each add a write call site produce
- * rows that git merges cleanly and a header that merges cleanly and WRONG. The
- * correct resolution is always "recompute from the merged tree".
+ * No prose to preserve, so nothing here is spliced -- the file is rewritten. Two
+ * branches that each add a write call site produce rows that git merges cleanly and
+ * a header that merges cleanly and WRONG, so the correct resolution is always
+ * "recompute from the merged tree" -- `node scripts/tenant-audit-census.mjs --write`,
+ * which is what the header this function emits tells a merging author to do.
+ *
+ * That resolution is not delegated to a merge driver: no `.gitattributes` entry
+ * covers this path, so `git check-attr merge` over it reads `unspecified` and git
+ * text-merges it like any other file. `scripts/check-tenant-audit-census.mjs` is the
+ * backstop -- a wrongly merged file fails the build loudly instead of landing
+ * silently.
  */
 export function renderCountsFile(census) {
   const t = census.totals;