alknet/tasks/call/client/from-jsonschema.md

id, name, status, depends_on, scope, risk, impact, level

id	name	status	depends_on	scope	risk	impact	level
call/client/from-jsonschema	Implement from_jsonschema adapter (schema-only registration, FromJsonSchema provenance, no handler)	completed	call/client/operation-adapter-trait	narrow	low	isolated	implementation

Description

Implement from_jsonschema in src/client/from_jsonschema.rs. This is the #4 gap — schema-only registration: produces HandlerRegistration bundles with no handler (FromJsonSchema provenance). Used for validation, discovery, and composition-graph construction without a runtime — type-checking a composition plan without executing it, building a UI of available operations without standing up the transports, etc.

Distinct from from_call (gap analysis DC-5 — confirmed, not a decision)

	from_jsonschema	from_call
Schema source	Provided directly (caller fetches, passes in)	Discovered over wire (services/list + services/schema)
Handler at call time	None (schema-only, FromJsonSchema provenance)	Forwards over QUIC (FromCall provenance, leaf)
Use case	Type validation, discovery, composition graph construction	Actually invoking remote operations

Keeping them separate preserves the "schema-only, no execution" use case (type checking, safe composition planning without runtime).

API

/// Schema-only registration: produce a HandlerRegistration bundle with
/// FromJsonSchema provenance and no handler. The caller fetches the JSON
/// Schema doc and passes it in; this adapter does no network I/O.
pub fn from_jsonschema(
    spec: OperationSpec,
    schema: serde_json::Value,
) -> HandlerRegistration;

The bundle:

• provenance: FromJsonSchema
• composition_authority: None (no composition — it's schema-only)
• scoped_env: None (leaf-equivalent — no reachability)
• capabilities: Capabilities::new() (empty — no outbound credentials, no handler to use them)
• remote_safe: false (default — ADR-028 §4; provenance-aware default)
• handler: a placeholder that returns a NOT_FOUND-style or INVALID_INPUT-style error if ever invoked. Since FromJsonSchema ops are Internal/not-remote-safe by default and have no composition authority, they should never be dispatched; the placeholder makes the type-level constraint hold (the Handler type requires a closure) and fails loudly if a bug routes a call to it.

OperationAdapter impl

from_jsonschema implements the OperationAdapter trait (from operation-adapter-trait). Because it does no I/O, the import() body contains no .await points — it trivially satisfies the async trait.

pub struct FromJsonSchema {
    spec: OperationSpec,
    schema: serde_json::Value,
}

#[async_trait]
impl OperationAdapter for FromJsonSchema {
    async fn import(&self) -> Result<Vec<HandlerRegistration>, AdapterError> {
        // No .await — pure parse. Validates schema shape if useful, returns bundle.
        Ok(vec![from_jsonschema(self.spec.clone(), self.schema.clone())])
    }
}

If the schema is malformed, return AdapterError::SchemaParse.

Why this is standalone (medium priority)

from_jsonschema doesn't depend on CallClient or from_call — it's pure parse with no transport. It's sequenced after operation-adapter-trait only because it implements the trait; if the trait lands first, this can proceed in parallel with call-client/from-call. It's medium priority because the primary consumers (runner, container service, agent) need from_call, not from_jsonschema; the schema-only use case is validation/discovery tooling.

Acceptance Criteria

• src/client/from_jsonschema.rs exists with from_jsonschema fn + FromJsonSchema struct
• from_jsonschema produces a HandlerRegistration with provenance: FromJsonSchema
• composition_authority: None, scoped_env: None, empty capabilities
• remote_safe: false (provenance-aware default, ADR-028 §4)
• Handler placeholder returns an error if invoked (no real handler)
• FromJsonSchema implements OperationAdapter (async, no .await in import)
• Malformed schema returns AdapterError::SchemaParse
• No network I/O (pure parse — caller fetches the doc)
• Unit test: from_jsonschema produces a bundle with correct provenance + None fields
• Unit test: placeholder handler returns error when invoked
• Unit test: OperationAdapter impl returns Ok with one bundle
• Unit test: malformed schema returns SchemaParse error
• cargo test -p alknet-call succeeds
• cargo clippy -p alknet-call --all-targets succeeds with no warnings

References

• docs/architecture/crates/call/client-and-adapters.md — from_jsonschema §, from_jsonschema vs from_call table
• docs/architecture/decisions/017-call-protocol-client-and-adapter-contract.md — ADR-017 §5 (FromJsonSchema impl)
• docs/architecture/decisions/022-handler-registration-provenance-and-composition-authority.md — ADR-022 (FromJsonSchema provenance, leaf-equivalent None fields)
• docs/architecture/decisions/028-callclient-peer-scoped-registry-filtering.md — ADR-028 §4 (remote_safe default false)
• tasks/call/client/operation-adapter-trait.md — prerequisite (the trait + AdapterError)
• docs/research/alknet-call-completion/gap-analysis.md — DC-5, implementation priority #4

Notes

from_jsonschema is distinct from from_call (DC-5): schema source is provided directly (caller fetches), there's no handler at call time, and the use case is validation/discovery/composition-graph construction without a runtime. It's pure parse with no transport, so it can proceed in parallel with call-client/from-call once the trait lands. The placeholder handler fails loudly if a bug ever routes a call to a schema-only op — they're Internal + not-remote-safe + no composition authority, so dispatch should never reach them.