D138 — Provenance stamp on materialized skills and agents, and two hashes per managed file¶

Decision. A materialized skill (its SKILL.md only) and agent carry a marker-delimited provenance block appended to the file, following the existing  / :end convention with the begin marker matched by prefix. It names the source KB, the artifact's path in that KB, the artifact's content hash, and the one remediation an agent can act on: local edits are replaced on the next sync, and the change belongs in artifact_write on that KB at that path. Bundled artifacts are stamped too, stating the Cartographer bundle as their source and offering no artifact_write instruction. Hooks, mcp descriptors and instructions are never stamped. The block carries no timestamp and no manifest revision, is rebuilt from the source content on every materialization (so re-stamping is a fixed point and an older block is replaced, never nested), and is applied client-side only — the KB's copy is untouched, like placeholder expansion.

ManagedFile gains materialized_hash: the hash of what was actually written, after expansion, stamping and per-provider translation. content_hash keeps meaning "the manifest artifact's hash", which is what ComputeDiff compares. An empty materialized_hash means unknown (any lockfile written before this change) and is never a mismatch.

Rationale. A materialized skill was indistinguishable from a hand-written one: every other managed artifact announces itself — the instructions block, the generated OpenCode plugin, the Codex MCP block, the bootstrap script — but the two kinds an agent actually reads did not. So an agent improving a skill had no address to send the improvement to, and no warning that its edit was about to be overwritten; with several clients on one KB the round trip was undiagnosable from the file itself. Naming the tool, the KB and the path inside the file is what makes the supported channel reachable without documentation the agent may not have.

Separating the two hashes was a prerequisite, and fixes a latent defect on its own: copyArtifactFiles returned the expanded hash and Apply stored it in content_hash, which ComputeDiff then compared against the manifest hash — so any artifact containing a {{repo:…}}/{{path:…}} placeholder compared unequal on every sync, was reported Updated, rewritten, and showed as permanent drift in cartographer status. Artifacts without placeholders were unaffected, which is why it went unnoticed; stamping would have made every skill and agent hit that path, turning a corner case into the default.