[SECURITY] Harden GitHub Workflows

[John McCall (lowlydba)]

Resolves zizmor 🌈 findings.

Going forward, these zizmor checks will be enforced by OMF Security Checks, which is now a required workflow for this, and all, public repos.

Note

The workshop staging deploy was already not working as intended, and fixing that is out of scope for this PR.

[github-actions]

🚀 Workshop branch preview deployed!

You can review your changes at https://staging.overturemaps.org/workshop/pr/10/index.html

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_{♻️ Last refreshed: 2026-04-09T15:33:39Z}

[github-advanced-security]

You are seeing this message because GitHub Code Scanning has recently been set up for this repository, or this pull request contains the workflow file for the Code Scanning tool.

What Enabling Code Scanning Means:

• The 'Security' tab will display more code scanning analysis results (e.g., for the default branch).
• Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results.
• You will be able to see the analysis results for the pull request's branch on this overview once the scans have completed and the checks have passed.

For more information about GitHub Code Scanning, check out the documentation.

[Copilot]

Pull request overview

This PR hardens the repository’s automation configuration in response to zizmor findings by tightening GitHub Actions permissions and pinning third-party actions, while also adjusting Dependabot update behavior.

Changes:

• Adds workflow concurrency controls and pins GitHub Actions to specific commit SHAs (plus disables persisted checkout credentials).
• Refactors PR-derived values used in shell commands into environment variables and scopes elevated permissions to the deploy job.
• Introduces a Dependabot cooldown to reduce update frequency/noise.

Reviewed changes

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

File	Description
.github/workflows/staging_deploy.yml	Pins actions by SHA, adds concurrency, narrows permissions, and reduces expression use inside run scripts.
.github/dependabot.yml	Adds a Dependabot cooldown window for GitHub Actions updates.

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