llm-ingestion-pipeline-security/CHANGELOG.md

# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [Unreleased]

> **Behaviour change, not a pure fix.** The three transform surfaces gain a
> refusal path they did not have. A caller that today passes a document larger
> than 1 000 000 characters gets an exception where it previously got a result.
> Both pinned consumers were measured against this before it was written; git
> pins are exact, so nobody picks it up without re-pinning.

### Added — input-size cap on the transform surfaces (OWASP LLM10)

`sanitize`, `fence` and `neutralize` now raise `OversizeInputError` above
`MAX_INPUT_CHARS` (1 000 000) instead of accepting text of any length. Since
`sanitize` is step 1 of `prepare_input` and only ever *removes*, that single
refusal bounds the whole input path.

They **reject** where the scanners **truncate**, and the asymmetry is the point:

- `scan_lexicon` / `scan_output` return findings. Reading a prefix costs
  detection in the tail and nothing else — a lossy answer, but an answer.
- `sanitize` / `fence` / `neutralize` return *content*. Truncating would return
  a shortened document (silent data loss for anything that persists the result)
  or a transformed prefix followed by an untransformed tail — a bypass, since an
  attacker chooses where in the document the payload sits.

The invariant the three now keep: **returned text is always fully transformed,
or not returned at all.**

`OversizeInputError` subclasses `ContractViolation`, so a pipeline already
bracketing its quarantined stage in `except ContractViolation` keeps failing
closed. Like its parent it is alert-routable: the message carries the size and
the cap, `details` names the refusing surface, and neither carries input.
`max_input_chars` is a per-call parameter, defaulting to the single calibrated
constant.

### Still uncapped, and deliberately

`scan_active_content` **called directly** and the okf link graph. Reached through
`scan_output`, `scan_active_content` inherits that function's cap. Both are
detection-shaped, so the truncate-and-flag mechanism transfers to them unchanged
— mechanical follow-up work, not a policy question. Recorded in
`docs/LIMITATIONS.md`.


## [0.3.4] — 2026-08-01

> **Denial-of-service fix on the INPUT path. Upgrade from 0.3.3.** 0.3.3 swept
> the 83 lexicon patterns arm by arm and left every other table on 0.3.2's
> hand-written rows. Generalising the sweep over all eleven regex-bearing modules
> found three more quadratic patterns — two of them on the input path, one in
> `sanitize`, the first thing every ingested document touches. No disposition
> changes: recall was measured case by case and nothing was lost. Earlier tags
> are not moved.

### Fixed — three quadratic patterns, two on the input path

Same class as everything 0.3.2 and 0.3.3 fixed: a run in front of a **required**
literal, so crafted input that never supplies the literal makes every start
position rescan the tail. Each exponent is read across four doublings, not from a
two-point ratio.

| Pattern | Crafted payload | Measured @ 100 000 | Exponent |
|---|---|---|---|
| `sanitize._HTML_COMMENT_RE` | `<!--` × N | **20.1 s** | 1.96–2.14 |
| `active_content.URL_IN_TEXT_RE` | `<a ` + `A` × N + `>` | 12.99 s / 14.9 s | 1.87–2.22 |
| `okf._MD_LINK_RE` | `[` × N | 7.1 s | 1.99–2.05 |

These are worse than the 0.3.3 findings, and the reason is a separate finding of
its own: `MAX_SCAN_CHARS` is applied in `scan_lexicon` and `scan_output` **only**.
`sanitize`, `neutralize`, `scan_active_content` and the okf link graph accept
input of any size, so there is no cap to extrapolate to. Now documented as a
residual in `docs/LIMITATIONS.md`; extending the cap into the input path changes
the contract for existing callers and is deliberately not done in a ReDoS patch.

Each fix is the one the pattern's own shape allows — the 0.3.3 lesson that a fix
choice must not be copied blindly from a neighbouring table:

- **`sanitize`** drops the regex for a `str.find` scan, semantically identical to
  the lazy `<!--.*?-->` it replaces. Excluding `<` from the run would lose every
  comment containing markup (`<!-- <b>x</b> -->` is the ordinary case); bounding
  the run would be a one-line carrier bypass of the exact construct the stripper
  exists to remove. The module's own "no catastrophic backtracking" comment was
  wrong in the same way `output`'s was before 0.3.2, and is corrected in place.
- **`URL_IN_TEXT_RE`** bounds its scheme run to an RFC 3986 scheme (`{0,63}`).
  Bounding is safe *here* only because this is a defanger applied inside a tag
  already flagged `active:raw-html`, so padding shifts where the match starts
  rather than evading detection. A lookbehind killing interior start positions
  was measured too and **rejected**: it drops `-http://evil.com` and
  `.http://x.com`, a one-character evasion of the defanger. Bounded, the pattern
  runs in 0.185 s at the full 1 000 000-char cap.
- **`okf._MD_LINK_RE`** excludes `[`, matching `active_content.MD_LINK_RE`
  exactly, including the nested-label trade already documented there.

### Changed — the sweep covers every regex surface, not one table

`docs/redos-sweep.py` now sweeps **150 patterns across 11 tables** (0.3.3 covered
83 in one). The collector is mechanical on both axes so no one has to remember to
list anything: it walks each module's namespace for compiled patterns, and it
derives each pattern's call mode from the module source, because `.sub()` and
`.finditer()` visit every start position where `.match()` cannot. A pattern
reachable only through a helper parameter gets the worst mode, marked `*` — the
fallback can over-measure but never miss.

Two arm shapes the generator cannot express are pinned by hand as a result: a tag
that *closes* around a long body (repeating-unit payloads never close it), and a
run of plain characters carrying no anchor at all. The `okf` destination run gets
no row on purpose: `[^)\s]+` cannot fail, so a pin for it could never go red.

A lexicon candidate flagged at ×2.8 measured **linear** across four doublings
(exponent 0.96–1.03) — the near-noise-floor false flag the script's own docstring
warns about, confirmed a second time.

676 tests (+10). Coverage matrix unchanged at 128/128 caught, 6/6 gaps holding.

## [0.3.3] — 2026-07-31

> **Denial-of-service fix, and a correction to 0.3.2. Upgrade from 0.3.2.** The
> sweep 0.3.2 shipped was incomplete, and it said otherwise. Two lexicon patterns
> were still quadratic — reachable through `scan_output`, not only on the input
> path. No disposition changes: recall was measured case by case and nothing was
> lost. The v0.3.2 tag is not moved.

### Fixed — two quadratic patterns in the lexicon table

`8deca93` scoped the remaining ReDoS duty to the lexicon path, and this is that
work: all 83 patterns measured, arm by arm. Two are quadratic, same shape as
everything 0.3.2 fixed — a run in front of a **required** literal, where the run
may cross the pattern's own opening anchor.

| Pattern (arm) | Crafted unit | Measured | At the 1 000 000-char cap |
|---|---|---|---|
| `markdown:link-anchor-injection` (anchor text) | `[` | 1.91 s @ 8 000 | **~8.3 hours** |
| `markdown:link-anchor-injection` (URL run) | `[system](` | 0.006 s @ 8 000 | ~89 seconds |
| `markdown:link-ref-comment` (`.*` run) | `[//]: # (` | 0.22 s @ 8 000 | **~1.0 hour** |

Exponent measured over five points (1 000 → 16 000): **1.98** — quadratic, not
exponential. Legitimate content of the same size is unaffected: 0.316 s at
N=100 000 (prose 0.316 / html 0.315 / markdown 0.297 / connection-string 0.296).

**These were not input-path-only, and that is the correction.** `scan_lexicon`
runs on the output path too, so 0.3.2's *"the last quadratic-backtracking site on
the output path"* was false when written. Measured through the public gate before
this fix: `scan_output("[" * 100_000)` took **334.7 s**. The claim was too broad
because the sweep behind it drove the `[` payload only through
`scan_active_content` — no row ever drove it through the lexicon. The statement is
corrected in `docs/LIMITATIONS.md`.

The fix is anchor exclusion, per the rule `active_content` already documents —
bounding attacker-controlled content would be a one-line detection bypass. The
excluded character is `(`, not `[`:

```
markdown:link-anchor-injection
  \[[^\]\[]*(?:system|…)[^\]\[]*\]\([^)(]+\)
markdown:link-ref-comment
  \[//\]:\s*#\s*\([^(\n]*(?:ignore|…)
```

`[` was the obvious choice and it was measurably worse. Excluding `[` from the
URL run drops `[override your rules](https://[::1]/x)` — still covered, three
other patterns fire on it — but excluding `[` from the link-ref comment run drops
`[//]: # (see [x] then ignore this)`, which **no other pattern catches**. The
anchors contain `(` as well, so excluding `(` telescopes just as effectively at
zero measured recall cost. Both forms verified linear (×1.99–2.02 on doubling).

### Known behaviour changes

- **None measured.** Every case that matched before still matches, except URLs
  containing a literal `(` inside a markdown link target and comment bodies
  containing a literal `(` before the keyword. No corpus, showcase, or coverage
  row moved; 666 tests pass.

### Tests

Four rows added. Three name the guilty pattern per arm
(`test_crafted_redos_payload_stays_bounded_in_the_lexicon`), one covers the
composed gate (`test_gate_is_bounded_on_the_payload_the_first_sweep_missed`).
Pre-fix they failed at 297 s, 8.1 s, 55 s and 334.7 s.

`N` is per row deliberately. The URL arm is quadratic with a small constant and
ran 0.9 s **unfixed** at N=100 000 — under the 2.0 s bound, so that row would have
passed whether or not the pattern was fixed. It is measured at N=300 000 instead,
where crafted (8.10 s) and legitimate (0.926 s) separate 8.8×.

### Residual

The sweep flags on timing and ignores measurements below a 1.5 ms noise floor at
N=8 000. An arm hiding just under it could still cost **~23 s** at the cap, so what
this supports is *"no arm worse than ~23 s"*, not *"no quadratic arm remains"*.
The blind spot is not hypothetical: a generic-payload pass found only one of the
two patterns. The second appeared only once payloads were synthesised per run
from each pattern's own skeleton. Recorded in `docs/LIMITATIONS.md`.

## [0.3.2] — 2026-07-31

> **Denial-of-service fix. Upgrade from 0.3.1.** The output gate could be made to
> spend hours on a single call by crafted input it accepts by design. No
> disposition changes for ordinary documents — the one measured exception is
> listed under *Known behaviour changes* below. The v0.3.1 tag is not moved.

### Fixed — 19 quadratic regex runs on the output path

`scan_output` claimed LLM10 self-safety on the grounds that its patterns contain no
nested quantifiers. That is true and it is not the property that matters. A run in
front of a **required** literal, reachable from a short anchor, is enough: crafted
input repeats the anchor and never supplies the literal, so every start position
rescans the tail. Quadratic, not exponential — and quadratic is sufficient here.

Measured, not argued (Python 3.14, this machine):

| Input | Time through `scan_output` |
|---|---|
| `<a:` × 100 000 (300 KB) | **458.7 s** |
| size-matched ordinary prose | 0.31 s |
| same payload extrapolated to the 1 000 000-char input the gate itself accepts | **~5.7 hours for one call** |

`max_scan_chars` does not mitigate this. It bounds the *input*; quadratic work on a
bounded input is still hours. That claim was stated in both `output.py` and
`calibration.py` and is corrected in both.

The fix is per pattern, not uniform:

- **`active_content` + the lexicon table (15 runs)** — exclude the character that
  opens the pattern's own anchor (`[` for markdown, `<` for tags), so a run cannot
  reach past the next start position and the per-start costs telescope. Verified to
  cost no recall: long URLs, long alt text, and `<` inside a quoted attribute all
  still match. Bounding instead would have been linear too, but wrong here — the
  content is attacker-controlled, so padding past a bound would be a one-line bypass
  of the EchoLeak class this table exists to catch.
- **`*-connstr` secret egress (4 runs)** — bound the password at the new
  `MAX_CONNSTR_VALUE` (256) in `calibration`. The exclusion fix is unavailable: the
  anchor character is `/`, and passwords containing `/` are the common case
  (measured — they match today).
- **`hybrid-xss:script-tag`** — had neither option, since its run is the script
  *body*, which may legitimately contain `<`. It now matches the opening tag and no
  longer requires `</script>`.

### Known behaviour changes

Two, both measured against the v0.3.1 tag rather than reasoned about:

- **A JWT used as a DB password, over 256 chars, is no longer CRITICAL.** The
  remaining detections (`entropy:base64-blob` HIGH, `egress:jwt-token` MEDIUM) top
  out below CRITICAL, so the any-tier block is lost: under `PRESET_TRUSTED_SOURCE`
  such a document moves from `fail_secure` to `quarantine_review`. Under
  `PRESET_USER_UPLOAD` it still `fail_secure`s, and a *generic* long password still
  trips `entropy:base64-blob` at CRITICAL with no change at all. The credential is
  never silently missed; on one preset it is held for review instead of halted.
- **`hybrid-xss:script-tag` now fires on prose that merely mentions `<script>`** —
  and this costs no consumer a disposition. Any text containing a literal
  `<script>` already produced `active:raw-html` at HIGH on 0.3.1, so the same
  document disposed identically before and after. The label is new; the outcome is
  not. By the same measurement, the fail-open this closed (an unclosed
  `<script>alert(1)`) was confined to `scan_lexicon` called on its own — through
  either composed gate, `active:raw-html` already caught it.

Both are recorded in `docs/LIMITATIONS.md` (still 29 items — these replace nothing).

### Method note

The defect was found by a composed-gate DoS test that stayed red after every
individual scanner had been made linear; the remaining 813× was the lexicon's six
`html-obfuscation` patterns. A per-scanner test alone would have shipped it. The
static shape analysis used to find candidates also missed `[\s\S]*?` in
`script-tag` — the sweep that matters is measurement, not a regex over regexes.

662 tests pass (was 642), and the suite is faster than before the fix.

## [0.3.1] — 2026-07-25

> **Regression fix. Upgrade from 0.3.0.** v0.3.0 made the high-untrust upload path
> unusable for ordinary documents — measured, not projected. `llm-ingestion-okf`
> projected the consequence from the 0.3.0 changelog text *before* the tag was cut;
> the release went out without the inbox being read. The v0.3.0 tag is not moved.

### Fixed — the upload path is usable again without losing EchoLeak detection

Measured on v0.3.0, both doors (`screen_output` under `PRESET_USER_UPLOAD` and
`okf.import_bundle` with `origin=EXTERNAL`): a document with **one ordinary remote
image** disposed `fail_secure`; one ordinary link, autolink or reference definition
disposed `quarantine_review`. Only documents with no external references persisted.
Two independent defects compounded, and both had to be fixed — either alone leaves
the path blocked:

- **Severity graded on construct type instead of URL shape.** `markdown-image` was
  HIGH for *any* external image, but the exfiltration primitive is not "an image" —
  it is a URL that moves bytes to a host the attacker controls.
  `![diagram](https://example.com/arch.png)` carries nothing. Severity now grades on
  shape: a URL that only *names* a remote document (http(s) or protocol-relative,
  no query, no userinfo, no percent-escapes, no opaque host label or path segment)
  is **LOW**; anything that can carry a value keeps the carrier's full severity.
  `raw-html` and `data:` URIs have no ordinary form and stay HIGH unconditionally.
  Opacity reuses `entropy`'s primitives — decodable base64 (≥20 chars), hex id
  (≥32), or Shannon entropy ≥4.4 at ≥24 chars — calibrated 2026-07-25 against real
  documentation URLs (worst legitimate token H=4.08; exfil payload segments
  4.36-4.54). New constants live in `calibration` with the rest.
- **The `quarantine_default` floor fired on *any* finding.** It rested on the premise
  that a finding is the exception; adding the active-content detector in 0.3.0 made
  every ordinary markdown link a finding, and the floor then held ordinary documents
  for review. The floor now fires at **MEDIUM+**. This is a no-op for every detector
  that shipped before 0.3.0 — the lexicon holds no LOW/INFO pattern and no other
  detector emits LOW (asserted in `tests/test_calibration.py`) — which is why this is
  a patch and not a minor.

**Unchanged, deliberately:** no new public API and no new preset (a middle tier is
0.4.0 work); the `allow_reserved=True` mode-b default stands — two independent
consumers document it as load-bearing; the gate still never rewrites content.

### Added

- **False-positive corpus covers ordinary markdown.** The 0.3.0 corpus had zero
  markdown links or images, asserted only under `PRESET_TRUSTED_SOURCE` (where every
  non-CRITICAL finding WARNs anyway), and drove the *input* path — so `scan_output`
  step 6, where active content actually lives, was never reached. That is how a
  regression this size passed 522 green tests. The corpus now carries realistic
  documents and asserts them on the **output gate under the upload preset**, plus a
  counter-corpus of exfil-shaped URLs (query, base64/hex path segment,
  percent-encoded payload, opaque subdomain, userinfo) that must still block.
- **Two new documented gaps** in `docs/LIMITATIONS.md`, both asserted by the coverage
  matrix: **pure beaconing** (a bare-path image on a hostile host still fetches, and
  the fetch is not graded) and **short opaque URL segments** (<24 chars, below what
  entropy can resolve). Percent-escapes counting as data-carrying is recorded there
  as a known false positive.

## [0.3.0] — 2026-07-25

> **A minor bump, not a patch — deliberately.** The changes under *Changed* alter what
> an existing caller observes with no code change on their side, so a `>=0.2,<0.3` pin
> stops here rather than absorbing them silently. Re-test that branch before widening
> the pin. Still alpha: the public API may change again before 1.0.

### Changed — observable gate behaviour (re-test before upgrading)

Three commits since v0.2.0 change dispositions for an unchanged caller. Two tighten
the gate; one loosens it.

- **`okf.import_bundle` no longer path-rejects reserved basenames.** At v0.2.0,
  `index.md` / `log.md` anywhere in a received bundle was an unconditional
  per-concept hard reject (FAIL_SECURE), and `import_bundle` took no keyword for it.
  The new `allow_reserved` keyword **defaults to `True`** on this mode-b
  *received-bundle* path, so those files are scanned — their body is the
  highest-priority injection surface — rather than refused, and may clear the floor
  and become mergeable. **This is the one loosening change:** content a v0.2.0
  consumer never saw can now reach it, so a consumer whose tests pin the v0.2.0
  reject must re-check, not just bump. A front-end materialising individual
  *uploads* must pass `allow_reserved=False` to keep the shadow-reject there;
  `validate_concept_path` still defaults to `False`.
- **Active content now reaches the disposition engine.** `scan_output` step 6 runs
  `scan_active_content`, so markdown images/links, reference definitions, autolinks,
  raw active HTML and `data:` URIs surface as `active:*` findings (OWASP LLM05 — the
  EchoLeak / CVE-2025-32711 class) instead of being admitted with `findings=[]`.
  These carry real severities (zero-click auto-fetch/execute HIGH, click-required
  MEDIUM), and two MEDIUM+ findings compound-escalate one tier, so a document that
  passed clean at v0.2.0 can now WARN, quarantine, or fail secure in both
  `screen_output` and `okf.import_bundle`.
- **Base64-wrapped secrets are now caught as egress.** The output gate's
  decode-and-rescan feeds decoded base64 plaintext through both the lexicon and the
  LLM02 secret-egress detector, so a base64-wrapped credential surfaces as
  `decoded:egress:*` instead of disappearing. Hex-wrapped remains a documented gap
  (`docs/LIMITATIONS.md`).

### Added — runnable threat-coverage matrix

A single declarative manifest (`llm_ingestion_guard.coverage`) that proves, in one
place, every vulnerability class the guard stops — and the documented gaps it does
not. Two consumers of the same source of truth:

- `python -m llm_ingestion_guard.coverage` — a narrated matrix
  (`class -> OWASP -> expected -> observed -> verdict`); exit 0 iff every caught
  class is caught and every documented gap holds. Stdlib-only, CI-usable.
- `tests/test_coverage_matrix.py` — asserts total recall over the core matrix
  (carriers, all 83 lexicon patterns, entropy/decode-rescan, active content, the
  contract asserters, the disposition engine, OKF T1–T7), asserts every documented
  gap still holds, and guards completeness (every lexicon pattern id, and every
  OWASP anchor claimed, has a case). Adds the full 25-pattern LLM02 secret-egress
  set and the container-layer front-end classes (CSV formula-injection, zip-slip,
  zip-bomb, symlink). +165 tests (357 → 522), no core dependency added.

This is the real-case validation gate ahead of a v1.0 freeze.

### Documentation — consumer adoption + README value proposition

- `docs/ADOPTION-BRIEF.md` — a self-contained brief a consumer repo (OKF
  second-brain / LLM wiki) can plan an inclusion from: the write-time trust-boundary
  argument, the two bookends + 8-step contract, the shipped OKF adapter
  (`import_bundle` mode-b), how to verify (coverage matrix), how to depend
  (stdlib-only core), and a checklist for *when/where* to wire it.
- README rewritten to lead with the write-time trust-boundary framing, add a
  first-class **OKF / LLM-wiki support (shipped)** section for `import_bundle`, a
  concrete **What it protects against** catalogue (attack classes grouped by OWASP
  anchor, driven by the coverage matrix), and correct the test badge (357 → 522).
  Every claim verified against the code.
- `docs/LIMITATIONS.md` — the full honest-limitations list (15 items + the four
  documented gaps + out-of-scope) moved out of the README, which now carries a
  high-impact summary + link, so protection and limits read in balance.

## [0.2.0] — 2026-07-06

### Added — OKF adapter (stream 1)

An OKF (Google Open Knowledge Format v0.1) adapter *on top of* the
format-agnostic core (`llm_ingestion_guard.okf`). The core stays `text ->
findings`; the adapter knows OKF structure and routes scannable regions into the
existing machinery. All TDD (failing test first), +61 tests. Verified against the
OKF `SPEC.md` (2026-07-06). See `docs/OKF-INGESTION-BRIEF.md` §8.

- `parse_frontmatter` — strict, reject-by-default frontmatter loader; refuses
  anchors, aliases, explicit tags, merge keys, block scalars and flow collections
  by construction, so YAML anchor/alias DoS and `!!python/object` coercion cannot
  occur (not a general YAML parser, by design). (T2)
- `scan_concept` — whole-concept scan surface: frontmatter values (incl.
  `description`, read first under progressive disclosure), `resource` and body all
  go through `scan_output`. (T1)
- `validate_concept_path` — path / reserved-name gate: rejects `..` traversal,
  absolute paths and `index.md` / `log.md` shadowing; returns the concept-ID. (T4)
- `validate_resource_url` — `resource` https allowlist: rejects non-https before
  commit (reject, not defang — the format imposes no scheme constraint itself). (T3)
- `stamp_concept` / `format_log_entry` — provenance stamping: origin × channel →
  trust × disposition per concept, emitted as `log.md` lines. Trust follows the
  origin, never the insertion channel. (T6)
- `import_bundle` — received-bundle iterator (mode b): validates each concept
  (path, frontmatter, resource, scan, stamp) independently; one bad concept is
  rejected fail-secure while the rest are still checked; the aggregate disposition
  is the most severe. (T7)
- `link_graph` / `resolve_link` / `extract_link_targets` — in-import cross-link
  graph: resolves `.md` links (bundle-absolute or relative) to concept-IDs, flags
  dangling links (the §7.2 dormant-injection signal) and rejects dangerous-scheme
  or bundle-escaping targets. (T5a)

### Deferred

- Cross-run persisted link graph (T5b) — catching a link planted in one run whose
  poisoned target is written in a *later* run (§7.2) needs durable graph state
  whose storage/ownership depends on the consuming pipeline. Deferred to the
  consumer-wiring stream; cross-run dormant links remain a documented residual
  risk (README honest-limitations).

## [0.1.0] — 2026-07-06 (alpha)

The stdlib-only core, built test-first (TDD) per `docs/PLAN.md`. Tagged `v0.1.0`.

### Added

- `report` — shared `Finding` / `Report` / `Severity` / `Source` types.
- `sanitize` — carrier stripping (zero-width, BIDI, Unicode-tag, HTML comment,
  `data:`); byte-identical on clean input.
- `entropy` — Shannon / base64-like / hex-blob detection; base64 decode-and-rescan.
- `lexicon` — JSON pattern data + loader; raw/normalized/homoglyph/rot13 variants;
  ReDoS-bounded, size-capped.
- `fence` — randomized per-call spotlight delimiter; attacker marker-strip.
- `neutralize` — opt-in defang of active-content output (byte-identical when clean).
- `output` — compose lexicon + entropy + decode-rescan over emitted text; secret
  egress patterns (OWASP LLM02); report-only, never mutates.
- `disposition` — WARN | QUARANTINE_REVIEW | FAIL_SECURE under a source-trust
  policy; compound-signal escalation; fail-**closed** when the scanner errors.
- `contract` — write-time asserters that raise: `assert_tool_less`,
  `assert_credential_allowlist`, `scoped_env`.
- `grounding` — the `SourceGroundingCheck` seam for semantic poisoning (interface
  only; `[judge]` implementation plugs in behind an extra).
- Top-level wiring — the `prepare_input` / `screen_output` §6 bookends plus the
  full public surface; end-to-end showcase and adversarial + false-positive corpora.

### Security

Pre-release hardening from an independent adversarial review (all TDD, failing
test first):

- `entropy` — decode-and-rescan now runs **before** false-positive suppression,
  so an injection blob prefixed with an SRI/media marker (to dodge the entropy
  finding) is still decoded and rescanned by the lexicon. Suppression gates only
  the entropy finding, never the decode.
- `output` — the invisible-carrier invariant now holds on the persist gate:
  `scan_output` flags zero-width / BIDI presence (`output:zero-width-present`,
  `output:bidi-present`) and `disposition` treats those plus
  `lexicon:unicode-tags-present` as any-tier carriers, so a carrier in model
  output fails secure even under a trusted policy.
- `contract` — `assert_credential_allowlist` catches a bare `<PROVIDER>_KEY`
  (e.g. `STRIPE_KEY`); the previous regex silently missed it (fail-open). The
  rule is deliberately broad (also flags `PARTITION_KEY`/`SORT_KEY` as loud,
  allowlistable false positives) — fail-loud beats fail-silent for isolation.
- `disposition` — `guard` runs `decide` inside its guarded block, so a malformed
  report can no longer escape the fail-closed guarantee.
- `output` — secret-egress placeholder suppression anchors word markers
  (`example`, `todo`, …) to a word boundary, so a real secret that merely
  *contains* such a word is no longer suppressed (fail-open egress miss closed).