diff --git a/src/resources/extensions/sf/subagent/index.js b/src/resources/extensions/sf/subagent/index.js
index dfbf37a3b..dcddb6e03 100644
--- a/src/resources/extensions/sf/subagent/index.js
+++ b/src/resources/extensions/sf/subagent/index.js
@@ -1452,9 +1452,15 @@ async function runSingleAgent(
 			};
 		}
 	}
-	// Feature flag: route through swarm dispatch instead of direct runSubagent.
+	// Subagent dispatch defaults to the swarm/messagebus path; the bash
+	// wrapper bin/sf-from-source used to set SF_SUBAGENT_VIA_SWARM=1 for
+	// that, but the web-launched sf goes node → src/loader.ts directly
+	// and bypasses the wrapper, so the default is enforced in code here.
+	// Opt out with SF_SUBAGENT_VIA_SWARM=0 (or =false) when running tests
+	// or workflows that need the direct-runSubagent subprocess path.
 	const swarmFlag = process.env.SF_SUBAGENT_VIA_SWARM;
-	if (swarmFlag === "1" || swarmFlag === "true") {
+	const swarmDisabled = swarmFlag === "0" || swarmFlag === "false";
+	if (!swarmDisabled) {
 		return runSingleAgentViaSwarm(
 			defaultCwd,
 			agent,
diff --git a/src/resources/extensions/sf/tests/subagent-via-swarm.test.mjs b/src/resources/extensions/sf/tests/subagent-via-swarm.test.mjs
index 4ae668858..8f0f1b6ab 100644
--- a/src/resources/extensions/sf/tests/subagent-via-swarm.test.mjs
+++ b/src/resources/extensions/sf/tests/subagent-via-swarm.test.mjs
@@ -84,11 +84,12 @@ afterEach(() => {
 
 // ─── Tests ─────────────────────────────────────────────────────────────────────
 
-test("SF_SUBAGENT_VIA_SWARM unset → runSubagent path, swarmDispatchAndWait NOT called", async () => {
-	// With the flag unset, runSingleAgent should NOT touch swarmDispatchAndWait.
-	// It will try to call runSubagent (from @singularity-forge/coding-agent), which
-	// will fail inside the test environment — we just need to confirm the swarm path
-	// was NOT taken.
+test("SF_SUBAGENT_VIA_SWARM=0 → runSubagent path, swarmDispatchAndWait NOT called", async () => {
+	// With the flag explicitly disabled, runSingleAgent should NOT touch
+	// swarmDispatchAndWait. It will try to call runSubagent (from
+	// @singularity-forge/coding-agent), which will fail inside the test
+	// environment — we just need to confirm the swarm path was NOT taken.
+	process.env.SF_SUBAGENT_VIA_SWARM = "0";
 	const agents = makeAgents();
 
 	try {
@@ -115,7 +116,7 @@ test("SF_SUBAGENT_VIA_SWARM unset → runSubagent path, swarmDispatchAndWait NOT
 	assert.equal(
 		swarmDispatchAndWait.mock.calls.length,
 		0,
-		"swarmDispatchAndWait should not be called when flag is unset",
+		"swarmDispatchAndWait should not be called when flag is explicitly disabled",
 	);
 });