Build order step 4 — the load-bearing port from the llm-security seed
(injection-patterns.mjs + string-utils.mjs), stdlib-only.
- injection_lexicon.json: 83 patterns (CRITICAL/HIGH/HYBRID/MEDIUM) as the
single source of truth (regex + id + severity + owasp + desc), compiled once
by a thin loader. Decoupled from the engine for a future TS port.
- scan_lexicon(text, source, max_scan_chars) -> Report: matches every pattern
against a deduped variant set (raw / normalized / homoglyph-folded / rot13),
plus unicode-tag presence signal and the cognitive-load trap.
- normalize_for_scan chain ported: unicode-tags -> bidi -> HTML-entities ->
unicode/hex/URL escapes -> whole-string base64 (reuses entropy.try_decode_base64)
-> collapse letter-spacing; plus fold_homoglyphs / rot13.
- Self-safety (OWASP LLM10): input-size cap (scan prefix + flag oversize) and
ReDoS-safe port — the two nested-.*? sub-agent patterns bounded to
(?:\S+\s+){0,N}?; verified true positives still fire.
- Non-Latin data (homoglyph map, BIDI block) built from explicit code points;
JSON non-ASCII kept as \uXXXX escapes.
24 tests; 55 green total.
[skip-docs]: README positioning + honest-limitations is a deliberate build-order
step-11 deliverable (steps 1-3 likewise left README frozen). README status line
("pre-implementation") is stale and flagged for the step-11 refresh.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K8GmKRCdsPjWYAKWsNgeQS
Build order step 3. Pure text -> findings detector ported from the
llm-security entropy-scanner seed:
- Length-calibrated Shannon-entropy classification (CRITICAL 5.4/128,
HIGH 5.1/64, MEDIUM 4.7/40).
- Shape floor: base64-like (len>100) / hex (len>64) reach at least MEDIUM
even when entropy alone does not trigger — the only path that catches hex
(16-symbol alphabet caps H at 4.0 < 4.7).
- Decode-and-rescan (must-have): base64 blobs that decode to printable text
are exposed on EntropyResult.decoded for a later lexicon rescan.
- FP suppression scoped to the text-relevant subset (base64 media data-URI
prefixes + SRI sha*- prefix); source-code-specific seed rules omitted.
Exposes ported primitives shannon_entropy / is_base64_like / is_hex_blob /
try_decode_base64. 16 new tests; full suite 31 green. Stdlib-only.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K8GmKRCdsPjWYAKWsNgeQS
