dsh-fabric-schema

Schema-enforced world state, evidence digests, and fail-closed certification for dsh-fabric — the Schema harness world-model pattern (hypothesis → verification → certified transaction), adapted from pi-fabric's proven schema and state layers onto DSH's durable fabric_mesh surface.

What it provides

• World state (state_* tools): an append-only Timeline of labeled, typed transitions stored as mesh topic events, a compare-and-swap head pointer recomputable from the log (state/current), a structural complexity ledger (state/complexity/*, TS/JS/TSX/JSX decision-point token fold), the executable goal predicate (state/goal), and fail-closed re-verification that certifies or revokes.
• Schema transactions (schema_* tools): schema_hypothesize binds a falsifiable hypothesis plus nonempty typed evidence to the current state and a git-aware workspace fingerprint; schema_verify fail-closed confirms every evidence item against the unchanged fingerprint and may issue one fresh session-bound single-use certificate; schema_commit consumes the certificate and atomically applies declared write/edit/delete operations with SHA-256 preconditions, postconditions, before-image journals, rollback/quarantine, and crash recovery, then records net committed text changes and complete-content SHA-1/SHA-256 transitions through the Harness mutation receipt API; schema_abort discards uncommitted artifacts.
• Enforcement (mode: off | audit | enforce): in enforce mode the tools/pre-execute gate denies direct edit/write calls with the Schema route; audit publishes would_block events without denying. Shell-produced mutations are outside this gate (pi-fabric's prewalk shell-mutation interception is a separate deferred surface); evidence commands run through the controller's own bounded runner.
• Guidance: a visibility-gated fabric:schema-guidance prompt section plus a ## Schema block in the Fabric operating prompt.

Records

All state and schema records are ordinary durable mesh records — inspectable with fabric_mesh (get_state, read_topic, snapshot) and folded into the same workspace-scoped durability as topics and actor mailboxes:

• topic fabric.state: transition, transition.committed, transition.rejected, state.certified, state.violated, state.goal.met
• topic fabric.schema: hypothesized, verified, verification_failed, committed, rolled_back, quarantined, aborted, would_block, blocked
• states: state/current (head), state/goal, state/complexity/<file>, schema/workspace, schema/hypothesis/<id>, schema/certificate/<token-hash>

Model-facing tools

state_get, state_transition, state_history, state_complexity, state_verify, state_goal, state_check_goal, schema_status, schema_hypothesize, schema_verify, schema_commit, schema_abort.

Composition

The tool row mounts in the fabric agent preset (packages/compaction/presets/fabric/agent.cordis.yml) so the tools and the guidance stay fabric-scoped:

- id: dsh-fabric-schema-tool
  name: 'dsh-fabric-schema/tool'
  config:
    mode: off        # off | audit | enforce

The mesh provider and storage are host-plane; the controller resolves the agent's workspace and cwd per call through the same identity rules as the mesh Consumer. Transaction journals and the commit lock live under the OS temp directory, keyed by the workspace identity hash.

Divergences from pi-fabric (documented)

• State keys are CAS-fenced mesh records; the mesh has no state delete, so a failed transition's absent-before ledger writes are retained (harmless — they only feed future delta measurements), while present-before writes are restored.
• Artifacts bind to the DSH session id (per-session invocation) instead of a per-run fabric_exec call id; certificates remain single-use and TTL-bounded.
• mode: enforce covers edit/write; bash and other tools are not gated (pi's prewalk handoff is a separate deferred surface).