Add versioned task context capsules

docs/CONTRACT.md

@@ -18,7 +18,9 @@ commit when Git is available; it cannot change repository state.
 - Edge schema: `schemas/edge.schema.json`, version 1.
 - Result envelope: `schemas/result.schema.json`, version 1.
 - Changeset schema: `schemas/changeset.schema.json`, version 1.
-- Index schema: version 2, disposable and reproducible.
+- Effective policy: `schemas/policy.schema.json`, version 1.
+- Task context capsule: `schemas/context-capsule.schema.json`, version 1.
+- Index schema: version 3, disposable and reproducible.
 - Index attestation: schema version 1, disposable and reproducible.
 - Core, CLI, and MCP server: version 1.3.0.dev0.
 - Incremental extraction cache: version 1, disposable and reproducible.
@@ -44,6 +46,12 @@ source hash. Errors use a stable code, direct message, structured details, and a
 tool when recovery is safe. MCP operations synchronize disposable index state under a project lock
 before reading or proposing. Canonical source validation remains fail-closed.
 
+Task-context retrieval derives a closed version-1 plan from a bounded task kind and the effective
+process policy. It executes against one immutable index transaction and returns generation-bound,
+hash-identified evidence, gaps, omissions, and provenance limitations. Project relation names
+remain authoritative. The core applies task semantics only to its versioned alias set and preserves
+every other allowed relation as unclassified.
+
 An atomic index build writes a whole-file SHA-256 attestation after complete graph, row, FTS, and
 SQLite integrity verification. A fresh process may use that receipt to verify an unchanged index
 without reconstructing all graph rows. A missing, malformed, or mismatched receipt falls back to
@@ -94,9 +102,10 @@ renderers. Render identity covers the canonical source hash, optional changeset
 and edge identities, view configuration, template hash, renderer contract, and exact parser version.
 
 An explicit CLI render atomically replaces one declared derived output. MCP can render a validated
-changeset only to its isolated preview path. Status recomputes expected output without writing and
-reports `current`, `stale`, `missing`, `unsafe`, or `oversized`. Input changes detected before atomic
-replacement fail without replacing the prior output.
+changeset only to its isolated preview path. Normal status verifies bounded source, configuration,
+template, output, renderer, and publication-receipt identities without reconstructing the output.
+Explicit deep status remains the side-effect-free full-render oracle. Input changes detected before
+atomic replacement fail without publishing a current receipt for stale output.
 
 Normal MCP access does not expose canonical application. An explicitly configured canonical
 applier registers one hash-bound application tool. No MCP mode exposes arbitrary renderer