fix(mosaic): honor seat-owned Gitea slots (#1529)

Co-authored-by: Mosaic fleet seat code-be-02 <[email protected]>

packages/mosaic/framework/tools/git/README.md

@@ -44,8 +44,8 @@ account/token configured through `tools/_lib/credentials.sh`. That means every a
 fleet commits, pushes, and opens PRs under one identity — with no cryptographic
 separation between an author and a reviewer.
 
-Both `git-credential-mosaic` and `get_gitea_token()` resolve an optional **per-agent
-identity**:
+`git-credential-mosaic`, `get_gitea_token()`, and the `gitea-mosaicstack` /
+`gitea-usc` arms of `load_credentials` resolve an optional **per-agent identity**:
 
 1. `MOSAIC_GIT_IDENTITY` environment variable, or
 2. `git config --get mosaic.gitIdentity` (set per-worktree; persists on disk across
@@ -65,6 +65,12 @@ The store is chosen by what the identity **is**, not by which file happens to ex
 `<brain>` is `MOSAIC_BRAIN_HOME` if set, else `~/.mosaic` — the same resolution
 `packages/mosaic/src/fleet/brain-home.ts` performs.
 
+The Gitea arms of `load_credentials` obtain a seat token through the production
+`git-credential-mosaic` entrypoint, rather than reading the slot directly. That retains
+the entrypoint's clean-environment and process-ancestry fence. The Gitea URL remains
+provider configuration from the service store. A caller-supplied `GITEA_TOKEN` retains
+its established environment precedence.
+
 **There is no precedence between the two stores and no fallback from one to the other.**
 A seat whose slot is empty is refused even when a same-named token sits in the framework
 store. One credential lives in exactly one location: a second copy is drift rather than