ctx-kb-ground

name	ctx-kb-ground
description	Read-only freshness audit over the kb's tracked sources (URLs, in-tree paths, MCP resources) declared in grounding-sources.md. Classifies each source's drift state, annotates the source-coverage ledger, and writes a ground closeout; flags drifted or new-to-kb sources for /ctx-kb-ingest. Never mints evidence, authors prose, or transitions ledger states.
allowed-tools	Bash(ctx:*), Bash(ls:*), Read, Edit

Ground the KB Against Its Tracked Sources

Walk the sources declared in .context/ingest/grounding-sources.md and report whether the kb's claims are still current. This is the "are we still current?" pass — a read-only freshness audit, not a re-ingest.

Each tracked source — URLs, in-tree paths, or MCP resources — gets resolved and classified as unchanged, drifted, gone, freshness opaque, or new to kb. The skill annotates the source-coverage ledger's Residue and Next action cells and writes a ground closeout summarising findings. It does NOT mint EV-### rows, author topic-page prose, transition ledger states, or modify Confidence bands; those are /ctx-kb-ingest's authority.

If a tracked source drifted or is new to the kb, this skill flags it and recommends a follow-up /ctx-kb-ingest. The declarative watch list in grounding-sources.md is what makes this skill distinct from ingest: it persists across sessions (ingest's source list is per-invocation) and tracks sources from anywhere the kb cites — public web, this repo's tree, behind an MCP server. Distance from the repo is irrelevant; what matters is that the kb depends on them for evidence.

Authoritative background reading: .context/ingest/KB-RULES.md §Authority boundary and §Source-coverage ledger; specs/kb-editorial-pipeline.md §Interface and §Edge Cases.

When to Use

• The user says "re-ground the kb", "check upstream", "are the docs still current?", or invokes the explicit slash form.
• Before a release / handover where source freshness matters.
• After an external vendor has shipped a version bump.
• Periodically (per the user's cadence) as kb hygiene.

When NOT to Use

• The user has new materials in hand (use /ctx-kb-ingest).
• The user is asking a content question (use /ctx-kb-ask).
• The user wants a structural audit (use /ctx-kb-site-review).

Authority Boundary (vs Other Skills)

• /ctx-kb-ground: read-only freshness audit over the sources listed in grounding-sources.md (URLs, in-tree paths, MCP resources). Annotates the source-coverage ledger's Residue and Next action cells; writes a ground closeout. May not mint EV-### rows, author prose, modify a topic page, change a Confidence band, or transition ledger states.
• /ctx-kb-ingest: handles anything this skill surfaces as new material to absorb.
• /ctx-kb-ask: handles read-only questions about kb content.
• /ctx-kb-site-review: handles structural audit (separate surface from source-freshness audit).

Usage Examples

/ctx-kb-ground

No arguments. Sources come from .context/ingest/grounding-sources.md.

Input Contract

The file .context/ingest/grounding-sources.md is the sole declaration surface. Each non-empty, non-comment line names a source (URL, in-tree path, MCP resource identifier) the user wants this skill to track. A line whose value is the literal NONE is a per-pass skip: this invocation does nothing and re-prompts on the next invocation. Lines beginning with # are comments.

There is no CLI argument for sources. To configure what this skill checks, edit grounding-sources.md.

Pre-Write Gates

Three distinct refusals, each leaves zero residue:

• .context/ missing → suggest ctx init and stop.
• .context/ingest/ missing → suggest ctx init --upgrade and stop.
• Kb scope undeclared → refuse with the scope message and stop.

Refuse-on-Empty

.context/ingest/grounding-sources.md may be in three states:

1. Missing or empty: file does not exist, or has only comments and blank lines. Prompt once:

   grounding-sources.md has no sources. List one source per line (URL, in-tree path, MCP resource). NONE on a line is a per-pass skip and re-prompts next invocation.

   Stop. Do not synthesize a list. Do not invent sources from the kb's source-map.md (that file's authority is ingest; grounding's declaration surface is separate by design).

2. Single line NONE: per-pass skip. Write no closeout; return exactly:

   grounding-sources.md is NONE for this pass; skipping. Edit .context/ingest/grounding-sources.md to set actual sources, or leave NONE to keep skipping.

   The next invocation re-prompts as in (1) above.

3. One or more sources listed: proceed to Process.

The empty-and-prompt path is the one exception to the refuse-on-empty pattern other mode skills enforce; the rationale is that grounding's declaration lives in a file the user owns (not in a slash argument), so a one-shot prompt is cheaper than forcing them to remember the filename.

Process

1. Verify pre-write gates. Refuse cleanly if any gate fails. Zero residue on refusal.

2. Read .context/ingest/grounding-sources.md. Handle the three states per §Refuse-on-empty.

3. For each declared source, in order of appearance:

   • Resolve the source: fetch the URL, stat the in-tree path, enumerate the MCP resource.
   • Cross-reference against .context/kb/source-map.md to find the kb's short-name for this source (if any). If absent, the source is new to the kb; record it as a flag to surface in the closeout (do not mint a source-map.md row; that is ingest's authority).
   • Check freshness using the strongest available signal:
     • URL: HTTP Last-Modified header, or ETag, or visible version stamp on the page; compare against the source-map.md row's dated: cell (if present).
     • In-tree path: file mtime + git SHA; compare against the evidence-index.md rows that cite the source by SHA (in-repo citations pin to a SHA at extraction time per KB-RULES.md §Evidence discipline).
     • MCP resource: whatever freshness primitive the resource exposes; if none, treat as opaque (record as "freshness opaque" in the closeout).
   • Classify the refresh outcome as one of:
     • unchanged: source has not drifted since the kb's last extraction; no ledger update needed.
     • drifted: source has changed; the kb's claims citing this source may be stale; advance the ledger row to a state that reflects the staleness:
       • If the row was comprehensive, advance to a typed superseded-pending annotation in the Residue cell (do not write a new state name; the state machine in KB-RULES.md is closed; Residue is the human-readable annotation surface).
       • If the row was anywhere prior to comprehensive, leave the state and add a drifted note in Residue
         • Next action set to the explicit /ctx-kb-ingest <slug> resumption.
     • : source returns 404, file deleted, MCP resource removed; flag for the user. The right resolution may be (with a named successor) or (out of scope); that judgment is the user's, not this skill's.

Edge Cases

Case	Expected behavior
grounding-sources.md missing or empty (only comments/blank)	Prompt once with the standard text; stop. No closeout.
grounding-sources.md single line NONE	Skip this pass with the standard skip text; stop. No closeout.
.context/ missing	Refuse; suggest ctx init. No residue.
.context/ingest/ missing	Refuse; suggest ctx init --upgrade. No residue.
Kb scope undeclared	Refuse with the scope message. No residue.
Source returns 404 / file deleted / MCP resource removed	Classify gone; flag; recommend the user choose superseded (with successor) or skipped (out of scope). Do not auto-transition.
Source unchanged since last extraction	Record unchanged in closeout's Refresh outcomes; no ledger update.
Source drifted since last extraction (URL bumped, file mtime newer than cited SHA)	Record drifted; annotate ledger row's Residue / Next action; recommend /ctx-kb-ingest <slug>. Do not modify topic-page prose.
Source has no freshness primitive (opaque)	Record freshness opaque (<date checked>); no ledger state change; surface in Flags so the user can decide cadence.
Source listed in grounding-sources.md but not in source-map.md (new to kb)	Classify new to kb; flag; recommend /ctx-kb-ingest <source> to admit. Do not mint a source-map.md row from this skill.
Source listed in grounding-sources.md but URL malformed or path nonexistent	Surface as a per-source error in the closeout's Flags; continue with remaining sources; do not abort the pass.
Source's source-map.md row has dated: but evidence-index.md rows lack

Anti-Patterns

• Minting EV-### rows from this skill. Evidence authoring is ingest's authority.
• Authoring topic-page prose from this skill. Page authoring is ingest's authority.
• Modifying a claim's Confidence band from this skill. Demotion is evidence work.
• Auto-transitioning a comprehensive ledger row out of comprehensive. State changes require ingest judgment; this skill annotates Residue / Next action only.
• Synthesising a source list when grounding-sources.md is empty. The declaration surface is the file the user owns.
• Inventing a freshness signal when none exists. "Freshness opaque" is the honest classification.
• Skipping the closeout once pre-write gates pass and at least one source was processed.

Output Contract

For pre-write refusals, return only the specified refusal text and stop. No residue.

For empty / NONE cases, return the matching prompt or skip text and stop. No closeout in those cases.

For passes that processed at least one source, end with this structured summary:

• Sources checked: count + one bullet each, classified (unchanged | drifted | gone | freshness opaque | new to kb).
• Ledger updates: count + one-line categories.
• Flags: count + categories.
• Closeout: filename on its own line.
• Next-recommended-action: explicit invocations to absorb drifted / new material (or none if every source was unchanged).

Quality Checklist

Before reporting completion, verify:

• Pre-write gates passed (or the matching refusal was returned with zero residue).
• Every declared source from grounding-sources.md was checked, classified, and recorded in Refresh outcomes.
• No EV-### row was minted, no topic-page prose was written, no Confidence band was changed, no ledger state was transitioned (only Residue / Next action annotated).
• Every drifted / gone / new to kb source has an explicit Next-recommended-action.
• Closeout written with all required frontmatter fields.