41 lines
2.1 KiB
Markdown
41 lines
2.1 KiB
Markdown
# Concelier Advisory Chunk Cache
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Status: draft · aligned with LNM v1 (frozen 2025-11-17)
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## Purpose
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- Reduce repeated `/advisories/{key}/chunks` rebuilds while preserving determinism and provenance integrity.
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- Provide consoles and debugging tools with transparent cache provenance (key material and TTL) to keep evidence chains auditable.
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## Cache key (deterministic)
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- Inputs (pipe-delimited, all lower-case where applicable):
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- `tenant`
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- `advisoryKey`
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- `chunkLimit`
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- `observationLimit`
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- `minimumLength`
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- `sectionFilter` (sorted, case-insensitive)
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- `formatFilter` (sorted, case-insensitive)
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- advisory fingerprint (hash of canonical advisory)
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- ordered observations: each `observationId@contentHash@createdAtTicks@format`
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- Implementation: `AdvisoryChunkCacheKey.Create` (WebService). Normalized ordering ensures replayability across nodes.
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- External disclosure: headers expose a hashed cache key (see below) rather than the full raw key.
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## Response transparency headers
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- `X-Stella-Cache-Key`: SHA-256 hex of the cache key (default 16 chars) for tamper-evident correlation.
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- `X-Stella-Cache-Hit`: `1` on hit, `0` on miss.
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- `X-Stella-Cache-Ttl`: configured TTL in seconds (0 when caching disabled).
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- Consumers may log these headers; do **not** treat them as stable API contract for filtering.
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## Determinism & safety
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- No PII in keys or headers; key inputs are tenant/advisory identifiers already present in requests.
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- Timestamps use UTC ticks; content hashes retain upstream digest prefix (e.g., `sha256:`) to distinguish sources.
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- Cache TTL defaults to 0 (disabled) unless configured; safe for offline/air-gapped deployments.
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## Testing notes
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- Unit coverage: `AdvisoryChunkCacheKeyTests` (ordering, filter casing) and `AdvisoryChunkBuilderTests` (observationPath pointers influence chunk IDs).
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- Integration tests should assert headers when cache is enabled; disable cache for tests that assert body-only determinism.
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## TODOs / follow-ups
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- Add integration test that exercises a cache hit path and validates transparency headers.
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- Document cache configuration knobs in `appsettings.*` once finalized.
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