feat(mosaic): complete credential lifecycle and fail closed

packages/mosaic/framework/tools/git/test-git-credential-mosaic.sh

@@ -85,6 +85,16 @@ out=$(run_helper "git.mosaicstack.dev" "")
 assert_eq "shared fallback: username" "username=git" "$(echo "$out" | grep '^username=')"
 assert_eq "shared fallback: password" "password=shared-mosaicstack-token" "$(echo "$out" | grep '^password=')"
 
+set +e
+out=$(run_helper "git.mosaicstack.dev" "" MOSAIC_AGENT_NAME=synthetic-seat 2>"$WORK_DIR/fleet-unset.stderr")
+rc=$?
+set -e
+err=$(cat "$WORK_DIR/fleet-unset.stderr")
+if [[ "$rc" -eq 0 || "$out" != *"quit=true"* || "$err" != *"reason=identity-required"* || "$err" != *"shared_path_entered=false"* ]]; then
+  echo "FAIL: fleet unset identity did not stop at the resolver marker" >&2
+  fail=1
+fi
+
 # ---------------------------------------------------------------------------
 # 2. git-supplied username resolves to an identity WITH a per-slot token ->
 #    that identity + token wins over the shared account.
@@ -120,6 +130,16 @@ out=$(run_helper "git.mosaicstack.dev" "no-such-agent")
 assert_eq "no per-slot token: username" "username=git" "$(echo "$out" | grep '^username=')"
 assert_eq "no per-slot token: password" "password=shared-mosaicstack-token" "$(echo "$out" | grep '^password=')"
 
+set +e
+out=$(run_helper "git.mosaicstack.dev" "no-such-agent" MOSAIC_AGENT_NAME=synthetic-seat 2>"$WORK_DIR/fleet-missing.stderr")
+rc=$?
+set -e
+err=$(cat "$WORK_DIR/fleet-missing.stderr")
+if [[ "$rc" -eq 0 || "$out" != *"quit=true"* || "$err" != *"reason=no-token-for-identity"* || "$err" != *"shared_path_entered=false"* ]]; then
+  echo "FAIL: fleet missing token did not stop at the resolver marker" >&2
+  fail=1
+fi
+
 # ---------------------------------------------------------------------------
 # 6. Correct per-slot token PATH is chosen per host: same agent id, different
 #    host prefix (gitea-usc- vs gitea-mosaicstack-).