Add CLAUDE.md (#771)

Author: johnbatty

CLAUDE.md

@@ -0,0 +1,109 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## What this repo does
+
+Auto-generates a Rust Azure DevOps API crate (`azure_devops_rust_api`) from the Azure DevOps OpenAPI spec (`vsts-rest-api-specs`, included as a git submodule). The pipeline is:
+
+1. **`vsts-api-patcher`** — reads `vsts-rest-api-specs/`, patches known issues in the OpenAPI JSON, writes `vsts-rest-api-specs.patched/`
+2. **`autorust`** — reads `vsts-rest-api-specs.patched/`, generates Rust source into `azure_devops_rust_api/src/`
+3. **`azure_devops_rust_api`** — the generated crate, compiled and published to crates.io
+
+## Commands
+
+### Full build (patch → generate → compile)
+```sh
+./build.sh
+```
+
+### Build individual components
+```sh
+# Run patcher only (from repo root)
+cd vsts-api-patcher && cargo run --release && cd ..
+
+# Run code generator only (from repo root)
+cd autorust && cargo run --bin ado-autorust --release && cd ..
+
+# Build generated crate
+cd azure_devops_rust_api && cargo build --all-features && cd ..
+```
+
+### Lint
+```sh
+cargo clippy --all-features -- --deny warnings
+cargo clippy --all-features --examples -- --deny warnings
+```
+
+### Check (faster than build, no generated output)
+```sh
+cd azure_devops_rust_api
+cargo check --all-features
+cargo check --all-features --examples
+```
+
+### Publish to crates.io
+```sh
+./publish.sh
+```
+
+## Architecture
+
+### Key distinction: generated vs. hand-written code
+
+**Do NOT edit generated files directly** — they are overwritten by `./build.sh`:
+- `azure_devops_rust_api/src/<module>/mod.rs` — generated API operations
+- `azure_devops_rust_api/src/<module>/models.rs` — generated model types
+
+**Hand-written source** (edit these directly):
+- `azure_devops_rust_api/src/auth.rs` — `Credential` enum (PAT + OAuth)
+- `azure_devops_rust_api/src/date_time.rs` — datetime serde helpers
+- `azure_devops_rust_api/src/telemetry.rs` — telemetry pipeline policy
+- `azure_devops_rust_api/src/headers.rs` — common header helpers
+
+### Code generator internals (`autorust/`)
+
+- `autorust/ado-autorust/src/main.rs` — entry point; maps each OpenAPI spec file to an output module
+- `autorust/codegen/src/codegen_operations/` — generates API operation code (clients, builders, responses)
+  - `create_client_and_builder.rs` — Pipeline/Transport/RetryOptions usage
+  - `request_builder_send.rs` — Pipeline::send() calls
+  - `request_builder_into_future.rs` — into_body()/into_model() calls
+  - `response_code.rs` — Response type definitions
+- `autorust/codegen/src/codegen_models.rs` — generates model structs/enums
+- `autorust/autorust.toml` — config for boxed/optional/invalid properties (fixes recursive type issues)
+
+### Patcher (`vsts-api-patcher/`)
+
+- `src/main.rs` — walks spec files, calls patcher, writes patched JSON
+- `src/patcher.rs` — all spec patches; patching logic keyed on spec filename
+
+### Generated crate structure
+
+Each Azure DevOps API area is a separate feature-gated module (e.g. `git`, `build`, `wit`). All features are listed in `azure_devops_rust_api/Cargo.toml`. API version is 7.1.
+
+## Updating `azure_core` / `azure_identity`
+
+See `SKILL.md` for the full process. Key files affected by breaking changes:
+- Codegen: `autorust/codegen/src/codegen_operations/` files (then re-run `./build.sh`)
+- Hand-written: `azure_devops_rust_api/src/auth.rs`, `telemetry.rs`, `date_time.rs`
+
+## Releasing
+
+See `SKILL.md` for the full process. Files to update: `azure_devops_rust_api/Cargo.toml` (version), `azure_devops_rust_api/README.md` (version in example snippet), `CHANGELOG.md`.
+
+## Updating the OpenAPI spec submodule
+
+```sh
+git submodule update --remote vsts-rest-api-specs
+git add .
+git commit -m "Updated vsts-rest-api-specs to latest revision"
+./build.sh
+cargo clippy --all-features -- --deny warnings
+cargo clippy --all-features --examples -- --deny warnings
+```
+
+## Commit message style
+
+- Dependency updates: `Update azure_core, azure_identity to X.Y`
+- Releases: `Release X.Y.0`
+- No conventional commit prefixes