v0.88.0

Added

• The Participant Fabric gained its operator surface: synapse participant list
  reports each registered provider driver's readiness (claude, codex, kimi, ollama,
  ollama-api, grok) without taking a turn, and synapse participant ask runs exactly
  one turn against one provider and prints the answer — or the full typed turn result
  with --json. Grok turns are refused while its stream schema remains unverified
  against a real binary.

• The participant surface gained the Fabric's deliberation layers:
  synapse participant exchange runs an opener turn and a reactor turn that sees the
  opener's result only as fenced peer data, and synapse participant convene fans a
  question out to a panel named as PROVIDER[:MODEL] seats, runs the conversation
  mode's cross-critique rounds (--mode auto selects colloquy, roundtable, or
  symposium from the panel shape), and in a symposium ends with the moderator's
  synthesis. Both print each turn as it is produced — or the full typed transcript
  with --json — and honour a cumulative --budget-usd ceiling.

• Release receipts' coordination-log commitments can now carry hub-key provenance:
  synapse merkle keygen generates the hub deployment's Ed25519 receipt-signing
  keypair (owner-only private key, distributable .pub whose key_id is derived
  from the key material), synapse verify-release --signing-key signs the Merkle
  commitment into verification.merkle_signature, and synapse policy-check --trusted-signing-key adds a merkle_signature decision so a verifier holding
  only the receipt and the .pub file learns which hub attested that exact log
  state — no access to the live log required. Verification is deny-by-default: a
  tampered root, an untrusted or transplanted key, a malformed envelope, and a
  signature with no commitment to cover all fail; only an unsigned receipt reads
  not_applicable.

• synapse causality contention weighs every pair of overlapping live claims —
  different owners, same worktree, intersecting path scopes — by what each
  contender's task gates downstream (causal descendants of its recorded events
  plus pending declared dependents, transitively) and recommends which agent
  yields; on an equal count the later claim yields. Advisory only: no claim is
  preempted, and the exit code doubles as a collision signal (0 no overlap,
  1 at least one pair).

• synapse status --json and synapse doctor --json emit their counts and
  verdicts as machine-readable JSON for monitoring scripts and CI health gates;
  doctor --json is a plain diagnostic and refuses the mutating and checklist
  flags so stdout stays one document. The install guide now surfaces
  synapse completions and synapse install-shell-hook.

Fixed

• Both multi-hub transports now decode peer-hub replies with the same
  depth-bounded JSON loader the hub applies to its own inbound frames, so a
  deeply nested reply from a malicious or compromised peer fails the poll (or
  refuses the forwarded claim) instead of recursing through an unbounded parse.
• The federation gate no longer downgrades a frame signed with a peered key to
  local processing when the connection presents no pinnable certificate — a
  plaintext socket or a certificate read that fails now denies such a frame
  outright, because the cross-domain authority its key claims can only be bound
  by a live pin. Frames signed with purely local keys are unaffected.