feat(client): typed shapes for the remaining agent tools; error.data at the boundary

[jrosskopf]

Summary

Contract-parity fixes (2/2, stacked on #409): the advertised agent-scope tools that had no typed request/response structs or client methods, and the error.data envelope the transport dropped.

• Typed shapes + client methods for fetch_blob, list_snapshots, list_op_authors, write_instance (wire key ref), and the HTTP session trio open_session/apply_op/close_session. Each struct matches the server handler's wire keys exactly; apply_op.op is the base64 Loro blob as the wire carries it; CloseSessionRequest::default() carries the wire default commit: true (a defaulted close commits, never a silent discard). ExpandResponse also decodes backend_projection so a write_instance caller can do a typed read-after-write.
• error.data at the client boundary: Error::JsonRpc gains data_code: Option<String> / retryable: Option<bool>, parsed from the gateway's error.data = {code, retryable} — the STABLE app-level refusal code the docs tell callers to branch on (several refusals share -32000). Both None when the envelope carries no data; existing { code, .. } matches are unaffected. (Note: per docs/spec/dx.md the error enum is a breaking-change surface — downstream struct-literal constructions of JsonRpc need the two new fields; the one in-workspace site, escurel-runner-core's reconciler test, is updated here.)

Skill sync in the same PR: references/05-consume-from-rust.md documents the new typed methods + error fields (replacing the stale "the live-CRDT trio and admin methods are added as … the types catch up" deferral); skill CHANGELOG 0.6.28 + VERSION.

Test plan

Real boundary, no mocks (crates/escurel-client/tests/typed_tools.rs, new):

• session_trio_round_trips_typed — real DuckDB CRDT backend sharing the indexer's DuckDB instance via try_clone (the production single-file wiring): open → apply (real Loro op) → list_op_authors shows the verified principal → close(commit) → expand observes the write-through body.
• list_snapshots_round_trips_typed — a whole-page write's snapshot is listed through the typed method.
• fetch_blob_round_trips_typed — real /ingest/upload of a born-digital text document into a document-backend skill, bytes fetched back verbatim (base64, declared content type); a non-document page decodes blob: None.
• write_instance_round_trips_typed — a real stateful loopback axum CRM as the openapi upstream; endpoint registered + overlay materialised via call_raw (admin plumbing), typed write_instance PATCHes it, live backend_projection read-after-write proves the upstream mutated.
• error_data_code_and_retryable_surface_typed — a reader_mode gateway refuses update_page and the typed error carries data_code: Some("read_only_replica"), retryable: Some(true).
• error_without_data_decodes_none — plain protocol error keeps both additions None.
• crates/escurel-types/tests/wire_contract.rs: write_instance_request_ref_rename, fetch_blob_response_wire_shape, list_op_authors_response_wire_shape, roundtrip_session_tools, close_session_commit_defaults_true.

Gate (un-piped exit codes): cargo fmt --check = 0, cargo clippy --workspace --all-targets -- -D warnings = 0, cargo test --workspace --all-targets = 0 (102 suites ok), cargo build --workspace --release = 0.

🤖 Generated with Claude Code

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