diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index c82c52c..84c2822 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -1,2 +1,13 @@
 # Every change to FieldCraft needs the maintainer's review before it merges.
 * @jyviko
+
+# Release and supply-chain paths, named explicitly so they stay owner-reviewed if the rule above
+# is ever relaxed: workflows and secrets use, packaging and signing, the updater, dependencies,
+# licences.
+/.github/ @jyviko
+/packaging/ @jyviko
+/crates/update/ @jyviko
+/Cargo.toml @jyviko
+/Cargo.lock @jyviko
+/ATTRIBUTION.md @jyviko
+/deny.toml @jyviko
diff --git a/.github/workflows/pages.yml b/.github/workflows/pages.yml
index 73a4824..258447f 100644
--- a/.github/workflows/pages.yml
+++ b/.github/workflows/pages.yml
@@ -33,6 +33,10 @@ env:
 
 jobs:
   build:
+    # POSTHOG_KEY lives in the `release` environment (main only, docs/releasing.md). The deploy job
+    # already uses github-pages and a job has one environment, so the build job reads the key: on
+    # main it runs in `release`, elsewhere in no environment and with an empty key.
+    environment: ${{ github.ref == 'refs/heads/main' && 'release' || '' }}
     runs-on: ubuntu-24.04
     timeout-minutes: 60
     steps:
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index a0debb4..5efb9c4 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -73,6 +73,9 @@ jobs:
   macos:
     name: macOS universal
     needs: version
+    # Signing, notarization and analytics secrets live in the `release` environment, which only
+    # `main` may use; a dry run on another branch asks for no environment and builds unsigned.
+    environment: ${{ github.ref == 'refs/heads/main' && 'release' || '' }}
     runs-on: macos-14
     timeout-minutes: 120
     outputs:
@@ -118,6 +121,9 @@ jobs:
     name: Linux x86_64
     needs: version
     # The oldest GitHub-hosted image, so the binaries need only glibc >= 2.35.
+    # Signing, notarization and analytics secrets live in the `release` environment, which only
+    # `main` may use; a dry run on another branch asks for no environment and builds unsigned.
+    environment: ${{ github.ref == 'refs/heads/main' && 'release' || '' }}
     runs-on: ubuntu-22.04
     timeout-minutes: 90
     env:
@@ -201,6 +207,9 @@ jobs:
   windows:
     name: Windows x64
     needs: version
+    # Signing, notarization and analytics secrets live in the `release` environment, which only
+    # `main` may use; a dry run on another branch asks for no environment and builds unsigned.
+    environment: ${{ github.ref == 'refs/heads/main' && 'release' || '' }}
     runs-on: windows-latest
     timeout-minutes: 90
     env:
@@ -230,6 +239,9 @@ jobs:
   release:
     name: Draft release (or dry-run artifacts)
     needs: [version, macos, linux, windows]
+    # Signing, notarization and analytics secrets live in the `release` environment, which only
+    # `main` may use; a dry run on another branch asks for no environment and builds unsigned.
+    environment: ${{ github.ref == 'refs/heads/main' && 'release' || '' }}
     runs-on: ubuntu-24.04
     permissions:
       contents: write
diff --git a/docs/privacy.md b/docs/privacy.md
index 21526f6..3725a06 100644
--- a/docs/privacy.md
+++ b/docs/privacy.md
@@ -86,5 +86,5 @@ A `command_run` as sent:
 The events and the policy are `fieldcraft_engine::usage`; the consent question and the settings
 are `crates/ui-egui/src/privacy.rs`; the desktop sender is `apps/fieldcraft/src/usage.rs`, the
 web one `apps/fieldcraft-web/src/usage.rs`. The PostHog project key is the build-time variable
-`FIELDCRAFT_POSTHOG_KEY`, which the release workflow and the Pages build of `main` set from the repository secret
+`FIELDCRAFT_POSTHOG_KEY`, which the release workflow and the Pages build of `main` set from the `release` environment secret
 `POSTHOG_KEY`; it is an ingest-only key. A new event or property is added here first.
diff --git a/docs/releasing.md b/docs/releasing.md
index 86fe54d..aa8c96a 100644
--- a/docs/releasing.md
+++ b/docs/releasing.md
@@ -51,7 +51,8 @@ about it, and the release notes say which of the two the draft contains.
 | `APPLE_PASSWORD` | An app-specific password for that Apple ID (appleid.apple.com › Sign-In and Security) |
 | `APPLE_TEAM_ID` | The 10-character team id of the Developer ID |
 
-Add them with `gh secret set <NAME> -R jyviko/fieldcraft`. With the certificate but without the
+Add them to the `release` environment ([Where the secrets live](#where-the-secrets-live)) with
+`gh secret set <NAME> --env release -R jyviko/fieldcraft`. With the certificate but without the
 three notarization secrets the app is signed and not notarized. A dmg made locally with
 `packaging/macos/package.sh` is ad-hoc signed unless `MACOS_SIGN_IDENTITY` names an identity
 in the keychain.
@@ -66,7 +67,7 @@ untrusted comment: minisign public key: FEF410EFEF5BAB21
 RWQhq1vv7xD0/uAOt8fqERP1hP+1UCM9U9QHTDYTYytWKiuedTkT7Lgr
 ```
 
-The secret half is the repository secret `FIELDCRAFT_SIGNING_KEY`: the whole secret key file
+The secret half is the `release` environment secret `FIELDCRAFT_SIGNING_KEY`: the whole secret key file
 (two lines), made without a password. With it, the release job signs `SHA256SUMS.txt` with
 [rsign2](https://github.com/jedisct1/rsign2) (pinned in `release.yml`), checks the signature
 against the public key in the source, and uploads `SHA256SUMS.txt.minisig`. Without it the
@@ -79,7 +80,7 @@ Setting it up, once:
 ```sh
 cargo install --locked rsign2 --version 0.6.7
 rsign generate -W -p fieldcraft-release.pub -s fieldcraft-release.key   # -W: no password
-gh secret set FIELDCRAFT_SIGNING_KEY -R jyviko/fieldcraft < fieldcraft-release.key
+gh secret set FIELDCRAFT_SIGNING_KEY --env release -R jyviko/fieldcraft < fieldcraft-release.key
 ```
 
 Keep an offline copy of the secret key file (a password manager, an encrypted backup) and
@@ -101,9 +102,39 @@ certificate is added.
 ## Usage analytics key
 
 The release builds (macOS, Linux and Windows jobs) build in the PostHog project key from the
-repository secret `POSTHOG_KEY` as `FIELDCRAFT_POSTHOG_KEY` ([privacy.md](privacy.md)). Without the
-secret the builds ask nothing and send nothing, as local and fork builds do. The web build on
-Pages has no key.
+`release` environment secret `POSTHOG_KEY` as `FIELDCRAFT_POSTHOG_KEY` ([privacy.md](privacy.md)).
+Without the secret the builds ask nothing and send nothing, as local, fork and dry-run builds do.
+The web build on Pages gets the key only when it runs from `main`: its build job then runs in the
+`release` environment (the deploy job already uses `github-pages`, and a job has one environment).
+
+## Where the secrets live
+
+Every release secret (the `APPLE_*` secrets, `KEYCHAIN_PASSWORD`, `FIELDCRAFT_SIGNING_KEY`,
+`POSTHOG_KEY`) is a secret of the GitHub Environment `release`, whose deployment branches allow
+`main` only. Repository secrets are readable by any workflow a writer can run on any branch;
+environment secrets reach only jobs that name the environment and run from an allowed branch, so a
+contributor with write access cannot read the signing keys from a branch of their own. The jobs
+that read them (`release.yml`'s macos, linux, windows and release jobs, `pages.yml`'s build job)
+ask for `release` only on `main`
+(`environment: ${{ github.ref == 'refs/heads/main' && 'release' || '' }}`); elsewhere the name is
+empty, the job runs in no environment, sees no secrets and builds unsigned. `.github/CODEOWNERS`
+keeps the workflows, packaging and updater under the owner's review.
+
+Moving them from repository secrets, once (the owner; each value comes from its own source file,
+never the shell history):
+
+```sh
+for n in APPLE_CERTIFICATE APPLE_CERTIFICATE_PASSWORD KEYCHAIN_PASSWORD APPLE_ID APPLE_PASSWORD \
+         APPLE_TEAM_ID FIELDCRAFT_SIGNING_KEY POSTHOG_KEY; do
+  gh secret set "$n" --env release -R jyviko/fieldcraft < "$n.txt"
+done
+gh secret list --env release -R jyviko/fieldcraft     # all eight listed
+# After a release run on main has signed with them:
+for n in APPLE_CERTIFICATE APPLE_CERTIFICATE_PASSWORD KEYCHAIN_PASSWORD APPLE_ID APPLE_PASSWORD \
+         APPLE_TEAM_ID FIELDCRAFT_SIGNING_KEY POSTHOG_KEY; do
+  gh secret delete "$n" -R jyviko/fieldcraft
+done
+```
 
 ## Choose and prepare the version