docs: document required permissions for all actions

.github/workflows/_local_on_pr.yml

@@ -38,6 +38,7 @@ jobs:
   setup-bazel-cache-tests:
     uses: ./.github/workflows/test-setup-bazel-cache.yml
     permissions:
+      actions: write
       contents: read
 
   unblock-user-namespace-for-linux-sandbox-tests:

.github/workflows/test-setup-bazel-cache.yml

@@ -18,6 +18,7 @@ on:
   workflow_dispatch:
 
 permissions:
+  actions: write
   contents: read
 
 jobs:

inter-repo-access/README.md

@@ -45,6 +45,10 @@ The rewrite host is derived from `github.server_url`, so the same behavior appli
 
 The action also exposes the selected token as `outputs.token` for cases where a token must be passed explicitly (for example, to a GitHub API call).
 
+## Required permissions
+
+This action configures git URL rewrites and optionally calls `actions/create-github-app-token` (which uses a JWT, not `GITHUB_TOKEN`). It does not call the GitHub API with `GITHUB_TOKEN` and requires no permissions of its own.
+
 ## Inputs
 
 - `github-app-client-id`: GitHub App client ID. When set, `github-app-private-key` is also required.

setup-bazel-cache/README.md

@@ -13,6 +13,17 @@ steps:
 
 Using `github.workflow` and `github.job` together gives each job its own cache automatically. Append a matrix identifier if the same job runs with different configurations that produce different build outputs.
 
+## Required permissions
+
+The job using this action needs:
+
+```yaml
+permissions:
+  actions: write
+```
+
+`actions: write` is required because deleting caches — which this action does to prune stale entries — is only available through the GitHub REST API. The internal runner token used for cache save and restore does not cover deletion; `GITHUB_TOKEN` with `actions: write` is the only supported mechanism for it.
+
 ## The cache only gets written from `main`
 
 PR and branch builds read from the cache but never write to it. Only builds on `main` populate it.

setup-qnx-sdp/README.md

@@ -13,6 +13,10 @@ It performs the following:
 - Configures access to qnx.com via `.netrc`.
 - Automatically removes the QNX license file and the `.netrc` entry when the job finishes (post-action).
 
+## Required permissions
+
+This action performs only local filesystem operations and does not call the GitHub API. No `GITHUB_TOKEN` permissions are required beyond whatever the rest of the job needs.
+
 ## How it works
 
 When invoked, the action runs these steps in order:

unblock-user-namespace-for-linux-sandbox/README.md

@@ -1,5 +1,9 @@
 # Unblock user namespace for linux-sandbox
 
+## Required permissions
+
+This action calls `sudo apparmor_parser` locally and does not call the GitHub API. No `GITHUB_TOKEN` permissions are required beyond whatever the rest of the job needs.
+
 Some tests require `linux-sandbox`.
 Starting with Ubuntu 23.10 Canonical has blocked Linux user namespaces for [security reasons](https://discourse.ubuntu.com/t/spec-unprivileged-user-namespace-restrictions-via-apparmor-in-ubuntu-23-10/37626/1).
 This action allows `linux-sandbox` to use Linux user namespaces via configuring `apparmor`.