Own knowledge-index generation in BCQuality (runtime + CI), not the consumer

The index is now produced by BCQuality itself: Entry's preparation step
rebuilds knowledge-index.json over the live, already-pruned clone at the start
of every run, and a new CI workflow validates the generator's health
(determinism, full coverage, selection-input integrity). Consumers no longer
invoke or know about the index.

Rebuilding over the pruned clone (vs shipping a committed full-corpus index)
keeps the index exact for any consumer policy: it can never list a denied
article, so policy-excluded rules cannot leak into discovery. READ now states
the index is discovery-only -- a finding must cite an article opened in full,
and rows whose file is absent are discarded before ranking.

- skills/entry.md: new 'Preparation -- knowledge index' precondition
- skills/read.md: index ownership + discovery-only invariant
- microsoft/skills/review/*.md (6): 'BCQuality builds' (not 'the filter emits')
- agent-consumption.md 5a: runtime+CI ownership rationale
- .github/workflows/knowledge-index.yml + scripts/Test-KnowledgeIndex.ps1: generator guard
- .gitignore: never commit the runtime index

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

microsoft/skills/review/al-performance-review.md

@@ -20,7 +20,7 @@ An orchestrator invokes this skill with either a `pr-diff` (the standard PR-revi
 
 ## Source
 
-Read the BCQuality knowledge index once — the `knowledge-index.json` the BCQuality filter emits at the root of the knowledge checkout. It lists every article that survived layer and allow/deny filtering and carries, per article, its `path`, `layer`, `domain`, frontmatter dimensions, `keywords`, `title`, and a one-line `description` hint — exactly the fields Relevance and Worklist consume. Take the index entries whose `domain` is `performance` as this skill's candidate set across every enabled layer; do not open the individual article files at this step. Open an article's full body only once it enters the Worklist below, so a review reads the index plus the handful of worklisted articles instead of every file under `*/knowledge/performance/**`.
+Read the BCQuality knowledge index once — the `knowledge-index.json` BCQuality builds at the root of the knowledge checkout (Entry's preparation step regenerates it over the live, already-filtered clone — see `skills/entry.md`). It lists every article that survived layer and allow/deny filtering and carries, per article, its `path`, `layer`, `domain`, frontmatter dimensions, `keywords`, `title`, and a one-line `description` hint — exactly the fields Relevance and Worklist consume. Take the index entries whose `domain` is `performance` as this skill's candidate set across every enabled layer; do not open the individual article files at this step. Open an article's full body only once it enters the Worklist below, so a review reads the index plus the handful of worklisted articles instead of every file under `*/knowledge/performance/**`.
 
 ## Relevance
 

microsoft/skills/review/al-privacy-review.md

@@ -20,7 +20,7 @@ An orchestrator invokes this skill with either a `pr-diff` (the standard PR-revi
 
 ## Source
 
-Read the BCQuality knowledge index once — the `knowledge-index.json` the BCQuality filter emits at the root of the knowledge checkout. It lists every article that survived layer and allow/deny filtering and carries, per article, its `path`, `layer`, `domain`, frontmatter dimensions, `keywords`, `title`, and a one-line `description` hint — exactly the fields Relevance and Worklist consume. Take the index entries whose `domain` is `privacy` as this skill's candidate set across every enabled layer; do not open the individual article files at this step. Open an article's full body only once it enters the Worklist below, so a review reads the index plus the handful of worklisted articles instead of every file under `*/knowledge/privacy/**`.
+Read the BCQuality knowledge index once — the `knowledge-index.json` BCQuality builds at the root of the knowledge checkout (Entry's preparation step regenerates it over the live, already-filtered clone — see `skills/entry.md`). It lists every article that survived layer and allow/deny filtering and carries, per article, its `path`, `layer`, `domain`, frontmatter dimensions, `keywords`, `title`, and a one-line `description` hint — exactly the fields Relevance and Worklist consume. Take the index entries whose `domain` is `privacy` as this skill's candidate set across every enabled layer; do not open the individual article files at this step. Open an article's full body only once it enters the Worklist below, so a review reads the index plus the handful of worklisted articles instead of every file under `*/knowledge/privacy/**`.
 
 ## Relevance
 

microsoft/skills/review/al-security-review.md

@@ -20,7 +20,7 @@ An orchestrator invokes this skill with either a `pr-diff` (the standard PR-revi
 
 ## Source
 
-Read the BCQuality knowledge index once — the `knowledge-index.json` the BCQuality filter emits at the root of the knowledge checkout. It lists every article that survived layer and allow/deny filtering and carries, per article, its `path`, `layer`, `domain`, frontmatter dimensions, `keywords`, `title`, and a one-line `description` hint — exactly the fields Relevance and Worklist consume. Take the index entries whose `domain` is `security` as this skill's candidate set across every enabled layer; do not open the individual article files at this step. Open an article's full body only once it enters the Worklist below, so a review reads the index plus the handful of worklisted articles instead of every file under `*/knowledge/security/**`.
+Read the BCQuality knowledge index once — the `knowledge-index.json` BCQuality builds at the root of the knowledge checkout (Entry's preparation step regenerates it over the live, already-filtered clone — see `skills/entry.md`). It lists every article that survived layer and allow/deny filtering and carries, per article, its `path`, `layer`, `domain`, frontmatter dimensions, `keywords`, `title`, and a one-line `description` hint — exactly the fields Relevance and Worklist consume. Take the index entries whose `domain` is `security` as this skill's candidate set across every enabled layer; do not open the individual article files at this step. Open an article's full body only once it enters the Worklist below, so a review reads the index plus the handful of worklisted articles instead of every file under `*/knowledge/security/**`.
 
 ## Relevance
 

microsoft/skills/review/al-style-review.md

@@ -22,7 +22,7 @@ An orchestrator invokes this skill with either a `pr-diff` or a `file-path`. The
 
 ## Source
 
-Read the BCQuality knowledge index once — the `knowledge-index.json` the BCQuality filter emits at the root of the knowledge checkout. It lists every article that survived layer and allow/deny filtering and carries, per article, its `path`, `layer`, `domain`, frontmatter dimensions, `keywords`, `title`, and a one-line `description` hint — exactly the fields Relevance and Worklist consume. Take the index entries whose `domain` is `style` as this skill's candidate set across every enabled layer; do not open the individual article files at this step. Open an article's full body only once it enters the Worklist below, so a review reads the index plus the handful of worklisted articles instead of every file under `*/knowledge/style/**`.
+Read the BCQuality knowledge index once — the `knowledge-index.json` BCQuality builds at the root of the knowledge checkout (Entry's preparation step regenerates it over the live, already-filtered clone — see `skills/entry.md`). It lists every article that survived layer and allow/deny filtering and carries, per article, its `path`, `layer`, `domain`, frontmatter dimensions, `keywords`, `title`, and a one-line `description` hint — exactly the fields Relevance and Worklist consume. Take the index entries whose `domain` is `style` as this skill's candidate set across every enabled layer; do not open the individual article files at this step. Open an article's full body only once it enters the Worklist below, so a review reads the index plus the handful of worklisted articles instead of every file under `*/knowledge/style/**`.
 
 ## Relevance
 

microsoft/skills/review/al-ui-review.md

@@ -22,7 +22,7 @@ An orchestrator invokes this skill with either a `pr-diff` or a `file-path`. The
 
 ## Source
 
-Read the BCQuality knowledge index once — the `knowledge-index.json` the BCQuality filter emits at the root of the knowledge checkout. It lists every article that survived layer and allow/deny filtering and carries, per article, its `path`, `layer`, `domain`, frontmatter dimensions, `keywords`, `title`, and a one-line `description` hint — exactly the fields Relevance and Worklist consume. Take the index entries whose `domain` is `ui` as this skill's candidate set across every enabled layer; do not open the individual article files at this step. Open an article's full body only once it enters the Worklist below, so a review reads the index plus the handful of worklisted articles instead of every file under `*/knowledge/ui/**`.
+Read the BCQuality knowledge index once — the `knowledge-index.json` BCQuality builds at the root of the knowledge checkout (Entry's preparation step regenerates it over the live, already-filtered clone — see `skills/entry.md`). It lists every article that survived layer and allow/deny filtering and carries, per article, its `path`, `layer`, `domain`, frontmatter dimensions, `keywords`, `title`, and a one-line `description` hint — exactly the fields Relevance and Worklist consume. Take the index entries whose `domain` is `ui` as this skill's candidate set across every enabled layer; do not open the individual article files at this step. Open an article's full body only once it enters the Worklist below, so a review reads the index plus the handful of worklisted articles instead of every file under `*/knowledge/ui/**`.
 
 ## Relevance
 

microsoft/skills/review/al-upgrade-review.md

@@ -20,7 +20,7 @@ An orchestrator invokes this skill with either a `pr-diff` (the standard PR-revi
 
 ## Source
 
-Read the BCQuality knowledge index once — the `knowledge-index.json` the BCQuality filter emits at the root of the knowledge checkout. It lists every article that survived layer and allow/deny filtering and carries, per article, its `path`, `layer`, `domain`, frontmatter dimensions, `keywords`, `title`, and a one-line `description` hint — exactly the fields Relevance and Worklist consume. Take the index entries whose `domain` is `upgrade` as this skill's candidate set across every enabled layer; do not open the individual article files at this step. Open an article's full body only once it enters the Worklist below, so a review reads the index plus the handful of worklisted articles instead of every file under `*/knowledge/upgrade/**`.
+Read the BCQuality knowledge index once — the `knowledge-index.json` BCQuality builds at the root of the knowledge checkout (Entry's preparation step regenerates it over the live, already-filtered clone — see `skills/entry.md`). It lists every article that survived layer and allow/deny filtering and carries, per article, its `path`, `layer`, `domain`, frontmatter dimensions, `keywords`, `title`, and a one-line `description` hint — exactly the fields Relevance and Worklist consume. Take the index entries whose `domain` is `upgrade` as this skill's candidate set across every enabled layer; do not open the individual article files at this step. Open an article's full body only once it enters the Worklist below, so a review reads the index plus the handful of worklisted articles instead of every file under `*/knowledge/upgrade/**`.
 
 ## Relevance