feat: implement readonly and writeonly

[dotkas]

Closes #105

[Copilot]

Pull request overview

Implements OpenAPI 3.0 readOnly / writeOnly semantics by treating them as directional markers (request vs response) and projecting models into request/response shapes, including split type naming (<Name>Request / <Name>Response) when a model is used in both directions (Issue #105).

Changes:

• Introduces direction-aware model projection via a new lowering pass that splits and rewrites models and service type references based on request/response reachability.
• Adds IR support for direction and per-field access (readOnly/writeOnly) and threads it through schema lowering and multipart lowering (including rejecting readOnly && writeOnly).
• Updates documentation, fixtures, generated snapshots, and tests/coverage to validate the new behavior (including cross-file import-mapping rejection for split targets).

Reviewed changes

Copilot reviewed 19 out of 22 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
docs/design.md	Documents the direction-projection model and naming/splitting rules for readOnly/writeOnly.
crates/oapi-codegen/tests/generated/server_auth.rs	Updates generated doc comment style output for multi-line descriptions.
crates/oapi-codegen/tests/generated/read_write_only.rs	Adds generated snapshot demonstrating request/response shape splitting for marked properties.
crates/oapi-codegen/tests/generated/combined_read_write_only.rs	Adds combined server/client generated snapshot exercising split models in operations, multipart, client, and server code.
crates/oapi-codegen/tests/generated.rs	Registers new generated snapshots and adds behavioral tests for split request/response shapes.
crates/oapi-codegen/tests/fixtures/server_unsupported_xfile_direction_split.yaml	Adds fixture for rejecting cross-file $ref into a schema that would split.
crates/oapi-codegen/tests/fixtures/schemas/compose_marked.yaml	Adds shared-schema fixture that triggers splitting to validate import-mapping rejection.
crates/oapi-codegen/tests/fixtures/read_write_only.yaml	Adds fixture for base direction-splitting behavior (struct, holder, alias, untouched).
crates/oapi-codegen/tests/fixtures/read_write_only_conflict.yaml	Adds fixture validating rejection when both marks are set.
crates/oapi-codegen/tests/fixtures/combined_read_write_only.yaml	Adds fixture covering direction behavior in a full API (request bodies, responses, multipart).
crates/oapi-codegen/tests/coverage.rs	Marks meta.readOnly/meta.writeOnly as supported and adds unsupported conflict + fixture coverage.
crates/oapi-codegen/src/lower/schema.rs	Lowers readOnly/writeOnly into per-field Access (including $ref targets) and rejects conflicting marks.
crates/oapi-codegen/src/lower/recurse.rs	Updates tests to account for the new Field.access field.
crates/oapi-codegen/src/lower/paths.rs	Ensures multipart extractor drops readOnly parts and threads direction access checks into multipart lowering.
crates/oapi-codegen/src/lower/mod.rs	Exposes the new direction module and re-exports split_by_direction.
crates/oapi-codegen/src/lower/direction.rs	New lowering pass implementing model/service projection and type rewriting for request/response shapes.
crates/oapi-codegen/src/loader.rs	Rejects import-mapping references to schemas that would split and adds a same-document scan to detect them.
crates/oapi-codegen/src/lib.rs	Integrates direction splitting into the main lowering pipeline (before prune and name checks) and models-only generation.
crates/oapi-codegen/src/ir.rs	Adds Direction and Access enums and the Field.access field to the IR.
crates/oapi-codegen/src/emit/usage.rs	Exposes direction usage data (direction_usage, adjacency, Usage) needed by the direction pass.
crates/oapi-codegen/src/emit/models.rs	Updates tests for the new Field.access field in test fixtures.
crates/oapi-codegen/src/emit/mod.rs	Improves doc emission to split multi-line descriptions into multiple /// lines.

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[Copilot]

Pull request overview

Copilot reviewed 19 out of 22 changed files in this pull request and generated no new comments.

Suppressed comments (2)

Previously missed (1) — in code that hasn't changed since the last review.

crates/oapi-codegen/src/lower/direction.rs:282

• This doc comment says project_service “drop[s] the multipart parts a request must not send”, but this function only rewrites types; multipart field dropping happens earlier during lowering (multipart_part_is_sent in lower/paths.rs). Please adjust the comment to avoid misleading future maintainers.

/// Point every API position at the shape of the direction it carries, and drop
/// the multipart parts a request must not send.

crates/oapi-codegen/src/loader.rs:459

• direction_split_schemas() treats a component schema with schema_data.read_only/write_only set (e.g. a shared primitive schema marked readOnly and referenced via $ref) as if it will be emitted as <Name>Request/<Name>Response. The lowering pass only splits models when a struct field ends up with Access != ReadWrite, so such “schema-level” marks can be used to mark a referencing property without the referenced schema itself being split. As a result, external_schema_name() can reject valid import-mapping references and the error message can describe shapes the models run never emits. Consider aligning direction_split_schemas() with the same “sensitive model” criteria as lower::direction (seed from object properties whose effective Access is not ReadWrite, then close over referrers), so only actually-split schemas are rejected here.

        let ident = crate::naming::to_ident(&chosen, crate::naming::Case::Pascal);
        if direction_split_schemas(&doc).contains(name) {
            let shape = ident.logical();
            return Err(Error::UnsupportedRef {
                reference: reference.to_owned(),

[Copilot]

Pull request overview

Copilot reviewed 19 out of 22 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 19 out of 22 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 19 out of 22 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 19 out of 22 changed files in this pull request and generated 1 comment.

[alchemax-housekeeper]

🎉 This PR is included in version 1.2.0-dev.1 🎉

The release is available on GitHub release

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