add canonical sigchain bundle format

docs/roadmap.md

@@ -576,10 +576,28 @@ resource-scoped capability decisions.
     backend receipt policies, required backend classes, old-policy witnessing
     of policy-change heads, cached-head rollback checks, and
     incomparable-history fork failure.
+  - `[x]` Define and implement the canonical `.sscb` on-disk/full-snapshot
+    bundle with deterministic record, disclosure, claim, and receipt objects.
+    - `[x]` Decoding rejects trailing bytes, noncanonical order, duplicates,
+      unknown references, mixed chains, and over-limit inputs.
+    - `[x]` `bundle-create` and `bundle-extract` convert record JSONL while
+      clearly preserving claims/receipts only in the canonical bundle.
+    - `[x]` `verify-sigchain` auto-detects JSONL or canonical bundles and binds
+      a bundle's namespace and chain ID to local trust.
+  - `[x]` Specify the backend-neutral distribution-source contract and a static
+    HTTP full-snapshot profile at
+    `/.well-known/sshsigchain/v1/<chain-id>/chain.sscb`.
+  - `[ ]` Implement automatic distribution fetchers.
+    - Acceptance criteria: an HTTP fetcher enforces streaming limits,
+      conditional caching, redirect policy, trust-tuple matching, accepted-head
+      ancestry, anchor policy, and fork failure.
+    - Acceptance criteria: the Iroh fetcher returns the identical canonical
+      bundle/object model and remains the only geth node-to-node transport.
   - `[~]` Add explicit CLI storage, signing, verification, publication, and
     import workflows for a pinned SSHSIGCHAIN trust tuple.
-    - `[x]` `geth keychain verify-sigchain` verifies a JSONL transport file
-      against an operator-pinned chain ID and OpenSSH root public key.
+    - `[x]` `geth keychain verify-sigchain` verifies JSONL interchange or a
+      canonical bundle against an operator-pinned chain ID, namespace, and
+      OpenSSH root public key.
     - `[ ]` Local record storage, signing, publication, import, and
       head-advance workflows are complete.
   - `[ ]` Persist accepted heads and require proof of extension before a source
@@ -602,8 +620,9 @@ resource-scoped capability decisions.
     - `[x]` An OpenSSH `ssh-keygen -Y` integration test signs and verifies an
       Authority v1 genesis link.
     - `[~]` The specification and reference implementation share base signing,
-      key-proof, commitment, and head-claim vectors.
-      - `[ ]` Publish the complete vector set in the specification.
+      canonical-bundle, key-proof, commitment, and head-claim vectors.
+      - `[x]` Publish outer-link and canonical-bundle framing vectors.
+      - `[ ]` Publish key-proof, commitment, head-claim, and receipt vectors.
     - `[ ]` Add independently generated cross-implementation vectors.
 
 - `[x]` SSH-admin-rooted keychain initialization.