Document trusted publishing

CONTRIBUTING.md

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+# Contributing to Artichoke – strftime-ruby
+
+Welcome to [Artichoke]. Thanks for taking the time to contribute.
+
+`strftime-ruby` implements Ruby-compatible `Time#strftime` formatting. If its
+formatting differs from Ruby or POSIX behavior, please [file an issue].
+
+## Setup
+
+This repository uses [mise] to manage Rust, Node.js, and repository development
+tools. Install the declared toolchains and text-formatting dependencies with:
+
+```sh
+mise install
+mise run pnpm-install
+```
+
+Run `mise tasks` to list the available development commands.
+
+## Validation
+
+Format, lint, and test changes with:
+
+```sh
+mise run fmt
+mise run lint
+mise run test
+```
+
+Pull requests must include appropriate tests and pass all required checks before
+merging.
+
+## Publishing
+
+Maintainers publish releases through crates.io trusted publishing. See
+[`docs/publishing.md`](docs/publishing.md) for the trust configuration, release
+procedure, and failure-recovery guidance.
+
+## Updating dependencies
+
+Regular dependency updates are handled by [Dependabot]. Keep dependency changes
+focused and run the full validation suite before merging them.
+
+[artichoke]: https://github.com/artichoke
+[dependabot]: https://docs.github.com/code-security/dependabot
+[file an issue]: https://github.com/artichoke/strftime-ruby/issues/new
+[mise]: https://mise.jdx.dev/

docs/publishing.md

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+# Publishing
+
+This crate is published to [crates.io] by the
+[`publish.yaml`](../.github/workflows/publish.yaml) GitHub Actions workflow.
+Publishing uses OpenID Connect (OIDC) trusted publishing. The repository does
+not store a long-lived crates.io API token.
+
+## Trust configuration
+
+The crates.io trusted publisher must match this tuple exactly:
+
+| Setting           | Value               |
+| ----------------- | ------------------- |
+| Crate             | `strftime-ruby`     |
+| GitHub owner      | `artichoke`         |
+| GitHub repository | `strftime-ruby`     |
+| Workflow          | `publish.yaml`      |
+| Environment       | `crates-io-publish` |
+
+The GitHub `crates-io-publish` environment accepts deployments only from tags
+matching `v*.*.*`. Repository rulesets make tags immutable after creation.
+
+The trusted publisher and GitHub environment are external configuration. Audit
+them against this document when changing release automation.
+
+## Prepare a release
+
+1. Open a release pull request that updates the version in `Cargo.toml` and
+   every repository-owned copy of that version, including `html_root_url`,
+   examples, and lockfiles when present.
+2. Run the repository's formatting, linting, and test commands.
+3. Run `cargo publish --dry-run` and inspect the packaged file list.
+4. Merge the release pull request only after its required checks pass.
+5. Wait for CI on the merged `trunk` commit to complete successfully.
+
+## Publish
+
+Create the release tag from the merged `trunk` commit. Tags use the exact
+`vX.Y.Z` form required by the workflow.
+
+```sh
+git switch trunk
+git pull --ff-only
+git tag -s "vX.Y.Z" -m "vX.Y.Z"
+git push origin "vX.Y.Z"
+```
+
+The publish workflow verifies that the tag has exact semantic-version syntax,
+that the tag version matches `Cargo.toml`, and that CI succeeded for the tagged
+commit. It then exchanges its GitHub OIDC identity for a short-lived crates.io
+credential and runs `cargo publish`.
+
+Monitor the Publish workflow through completion, then verify the new version on
+crates.io and docs.rs.
+
+## Failed releases
+
+Do not move or delete a release tag. Tag immutability is an intentional release
+integrity control.
+
+If publishing fails before crates.io accepts the version, fix the failure on
+`trunk` and prepare a new patch release. Before retrying a transient failed
+workflow, confirm that crates.io does not already contain the version and that
+the tag still points to the intended, green commit.
+
+[crates.io]: https://crates.io/crates/strftime-ruby