feat(calibration): add calibration.json, marked transcribed-only

The risk-score tier constants, verdict thresholds, risk-band cutoffs and
posture grade thresholds. Constants only — the log scaling and the if/else
chains that consume them are engine and stay in the consumer.

This file is the exception in this repository and is marked as such in its
own verification block. Every other data file here was rebuilt from its
commons JSON and diffed against an imported module. This one arrived as a
human-written PROSE SUMMARY of severity.mjs, so there was nothing to import
and nothing to diff. verified: false, with the two skipped checks named
rather than a caveat attached to a pass.

The consequence inverts this repository's central rule and the file says so:
for every other file a disagreeing consumer is wrong; for this one, until the
module arrives in executable form, a disagreement is not automatically the
consumer's bug.

What COULD be checked was: bands are contiguous and non-overlapping across
0-100, the BLOCK trigger (65) is exactly the Critical band floor, the WARNING
trigger (15) is exactly the Medium band floor, and the per-tier reachable
minima recompute exactly (80/48/20/4, exact because log2(2) is 1).

Corrects README and the extraction plan in the same commit: both promised
entropy floors, scan caps and disposition ranks. None arrived — 0 occurrences
each across the whole dump. Named in the file under not_supplied so the
absence is visible rather than inferred, and both rows now describe what is
actually present.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FaYqid3mejFmd9ZHsiHgp3

docs/extraction-plan.md

@@ -52,7 +52,7 @@ data, never from recollection or inference.
 | `signatures/secret-egress.json` | `hooks/scripts/pre-edit-secrets.mjs` — `SECRET_PATTERNS`, the **18-entry hook table**, NOT the PCRE-flavored agent-consumed variant in `knowledge/secrets-patterns.md`. *(Corrected 2026-08-09: this row originally named `knowledge/secrets-patterns.md` as the source file. The delivered dump named `pre-edit-secrets.mjs` and stated explicitly that the two are different files. The row now names the file that was actually delivered.)* |
 | `signatures/malware-signatures.json` | `knowledge/signatures.json` (the SIG scanner) |
 | `signatures/active-content.json` | currently only in a guard repo's `active_content.py`. If unavailable: stub with a version field and a TODO naming the source |
-| `calibration/calibration.json` | `scanners/lib/severity.mjs` — thresholds + scanner caps |
+| `calibration/calibration.json` | `scanners/lib/severity.mjs` — risk-score tier constants, verdict thresholds, risk-band cutoffs, posture grade thresholds. *(Corrected 2026-08-09: this row said "thresholds + scanner caps" and the README said "entropy floors, scan caps, disposition ranks". No scan cap, entropy floor or disposition rank was delivered — searched across the whole dump: 0 occurrences each. Both rows now describe what arrived.)* |
 | `mapping/owasp-map.json` | `scanners/lib/severity.mjs` — `OWASP_MAP` (+ 3 sibling maps in the same file) |
 | `schema/finding.schema.json` | modelled on `scanners/lib/sarif-formatter.mjs`'s SARIF shape |
 | `conformance/` | union of the guard repo's `coverage.py` matrix (126 classes + 4 gaps-must-hold) and `llm-security/examples/` |
@@ -222,6 +222,38 @@ and the rest are reproduced as opaque keys. Deliberately not inherited: the dump
 fallback map inside one of `llm-security`'s own agent definitions covers only part of the
 prefix set — that is drift in the consumer, and the complete 16-prefix set is what moves here.
 
+### `calibration/calibration.json` — transcribed 2026-08-09
+
+Source: `llm-security/scanners/lib/severity.mjs`, delivered as a **prose summary** inside
+operator dump 2/2 — not as source code.
+
+**This file is the exception in this repository, and it is marked as such in its own
+`verification` block.** Every other data file here was rebuilt from its commons JSON and
+diffed against an imported module. There was nothing to import here: the constants arrived
+as human-written prose describing the module. The differential check was therefore not run
+— not "passed with caveats", not run — and the file records `verified: false` with the
+specific checks that were skipped.
+
+| Check | Method | Result |
+| --- | --- | --- |
+| JSON well-formed, `version` present | `python3 -m json.tool` | pass |
+| Risk bands are contiguous and non-overlapping | compared each band's `max + 1` to the next band's `min` across 0–100 | contiguous, no gap, no shared value |
+| Band boundaries agree with the verdict thresholds | compared the BLOCK and WARNING score triggers to the band lower bounds | BLOCK 65 = Critical band min; WARNING 15 = Medium band min |
+| `reachable_minimum` is arithmetic, not a new claim | recomputed `base + min(cap, log2(2) * mult)` independently for all four tiers | 80 / 48 / 20 / 4 — exact, because `log2(2)` is exactly 1 |
+| Rebuild-from-commons and diff against source | **not run** — no importable source | — |
+| Differential scoring over a corpus | **not run** — the formulas are engine and were not supplied in runnable form | — |
+
+Recorded in the file as `not_supplied`, so the absence is visible rather than inferred: the
+README and this plan both promised **entropy floors, scan caps and disposition ranks**. None
+were delivered. Searched across the entire dump message: `entropy` 0 occurrences,
+`disposition` 0, `rank` 0, `floor` 0. Both descriptions have been corrected to name what
+arrived rather than what was expected.
+
+The consequence is stated in the file and is worth repeating here, because it inverts this
+repository's central rule: for every other file, a consumer that disagrees is wrong. For this
+one, until the module is supplied in executable form, a disagreement is not automatically the
+consumer's bug.
+
 ## Definition of done for v0.1.0
 
 1. Repository initialized, Forgejo remote `open/llm-security-commons`, MIT, `STATE.md`