diff --git a/scripts/mosaic-task.mjs b/scripts/mosaic-task.mjs
index 12610036..b224cf43 100755
--- a/scripts/mosaic-task.mjs
+++ b/scripts/mosaic-task.mjs
@@ -210,12 +210,25 @@ function runTask(taskFile) {
 
   const startedAt = new Date();
   const stderrFile = path.join(runDir, "stderr.txt");
+
+  // Sanctioned mission injection: point the container at the run snapshot's
+  // CONTAINER path (dataRoot maps to /var/lib/mosaic in the image).
+  const spawnEnv = { ...process.env };
+  spawnEnv.MOSAIC_ADAPTER = resolved.execution.adapter;
+  if (task.missionSnapshot) {
+    const relative = path.relative(resolved.dataRoot, runDir);
+    if (relative.startsWith("..") || path.isAbsolute(relative)) {
+      fail(4, `run directory is outside the configured dataRoot: ${runDir}`);
+    }
+    spawnEnv.MOSAIC_MISSION_FILE = `/var/lib/mosaic/${relative.split(path.sep).join("/")}/mission.json`;
+  }
+
   const proc = spawnSync(
     "docker",
     ["compose", "run", "--rm", "-T", "mosaic-agent", task.prompt],
     {
       cwd: PROJECT_ROOT,
-      env: process.env, // MOSAIC_DATA_ROOT / MOSAIC_PROVIDER / MOSAIC_MODEL resolved by run-task.sh
+      env: spawnEnv,
       input: "", // stdin detached: print mode must never wait on a terminal (see issue #5)
       encoding: "utf8",
       maxBuffer: 16 * 1024 * 1024,
diff --git a/scripts/test-config.sh b/scripts/test-config.sh
index cc5e34b5..b1b5d5a1 100755
--- a/scripts/test-config.sh
+++ b/scripts/test-config.sh
@@ -40,6 +40,20 @@ cfg() { printf '%s' "$2" > "$SANDBOX/$1"; }
 
 DATA_ROOT="$SANDBOX/data"
 
+# --- adapter selection (M4) ---
+cfg default-adapter.json '{"configVersion":1,"environment":"development","dataRoot":"'$DATA_ROOT'","execution":{"backend":"docker","provider":"zai","model":"m"}}'
+MOSAIC_CONFIG="$SANDBOX/default-adapter.json" $CONFIG_OP validate | grep -q '"adapter": "pi"'
+check "absent adapter defaults to pi" $?
+
+cfg mock-adapter.json '{"configVersion":1,"environment":"development","dataRoot":"'$DATA_ROOT'","execution":{"backend":"docker","provider":"zai","model":"m","adapter":"mock"}}'
+expect_exit "adapter mock validates" 0 -- env MOSAIC_CONFIG="$SANDBOX/mock-adapter.json" $CONFIG_OP validate
+
+cfg bad-adapter.json '{"configVersion":1,"environment":"development","dataRoot":"'$DATA_ROOT'","execution":{"backend":"docker","provider":"zai","model":"m","adapter":"claude"}}'
+expect_exit "unsupported adapter exits 2" 2 -- env MOSAIC_CONFIG="$SANDBOX/bad-adapter.json" $CONFIG_OP validate
+
+MOSAIC_CONFIG="$SANDBOX/mock-adapter.json" $CONFIG_OP env | grep -q "MOSAIC_ADAPTER='mock'"
+check "env exports adapter" $?
+
 # --- bootstrap ---
 rm -f "$SANDBOX/config.json"
 expect_exit "bootstrap creates default when absent" 0 -- \