diff --git a/integrationTests/fixtures/path-segment-routing-app/config.yaml b/integrationTests/fixtures/path-segment-routing-app/config.yaml
new file mode 100644
index 0000000..a547e1c
--- /dev/null
+++ b/integrationTests/fixtures/path-segment-routing-app/config.yaml
@@ -0,0 +1,44 @@
+# Integration test fixture: verifies the OAuth Resource correctly extracts
+# the providerName from the URL path segment, NOT the literal "oauth" prefix.
+#
+# Two providers are configured with distinctive client_ids. A request to
+# /oauth/<name>/login should redirect with that provider's client_id. If
+# parseRoute were to extract the literal "oauth" path segment as providerName
+# (the symptom Dawson reported on 2026-05-22 from CM/Studio), the request
+# would NOT produce a tenant-shaped 302 — it would either route to the
+# oauth-named decoy provider with action='oac-oauth-tenant' (an unknown
+# action → 404) or route to some other unintended state. The exact failure
+# shape depends on parseRoute's specific regression; the assertion only
+# requires that the tenant.test authorizationUrl + tenant client_id
+# appear in the redirect.
+#
+# The tenant provider name deliberately contains the substring "oauth" so
+# this fixture also guards against an over-aggressive stripping regression
+# (e.g., parseRoute mangling /oauth/ matches that occur inside the segment
+# rather than only at the prefix).
+
+rest: true
+
+'@harperfast/oauth':
+  package: '@harperfast/oauth'
+  providers:
+    # Provider literally named "oauth" — present specifically as a decoy.
+    # If parseRoute is broken and treats "oauth" as the providerName, this
+    # is what would (incorrectly) be selected as the provider.
+    oauth:
+      provider: generic
+      clientId: ${OAUTH_DECOY_CLIENT_ID}
+      clientSecret: decoy-secret
+      authorizationUrl: 'http://decoy.test/authorize'
+      tokenUrl: 'http://decoy.test/token'
+      userInfoUrl: 'http://decoy.test/userinfo'
+    # Tenant-style provider with a distinctive client_id we can assert on.
+    # The name contains "oauth" as a substring to catch over-aggressive
+    # path-stripping regressions in addition to the prefix-extraction case.
+    oac-oauth-tenant:
+      provider: generic
+      clientId: ${OAUTH_TENANT_CLIENT_ID}
+      clientSecret: tenant-secret
+      authorizationUrl: 'http://tenant.test/authorize'
+      tokenUrl: 'http://tenant.test/token'
+      userInfoUrl: 'http://tenant.test/userinfo'
diff --git a/integrationTests/fixtures/path-segment-routing-app/package.json b/integrationTests/fixtures/path-segment-routing-app/package.json
new file mode 100644
index 0000000..46a896d
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+++ b/integrationTests/fixtures/path-segment-routing-app/package.json
@@ -0,0 +1,6 @@
+{
+	"name": "path-segment-routing-app-fixture",
+	"private": true,
+	"type": "module",
+	"description": "Integration-test fixture for OAuth Resource path-segment routing. The @harperfast/oauth dep is installed at test setup time via scripts/install-fixtures.js (npm pack + install); harper is resolved from the repo root."
+}
diff --git a/integrationTests/path-segment-routing.test.ts b/integrationTests/path-segment-routing.test.ts
new file mode 100644
index 0000000..7d3ef45
--- /dev/null
+++ b/integrationTests/path-segment-routing.test.ts
@@ -0,0 +1,75 @@
+/**
+ * Regression guard for the symptom Dawson reported on 2026-05-22 (CM/Studio
+ * Okta SSO):
+ *
+ *   "providerName is 'oauth', not the {configId} described, that isn't passed"
+ *
+ * If parseRoute extracted the literal "oauth" path prefix as providerName
+ * (rather than the segment after it), requests to /oauth/<tenantId>/login
+ * would resolve to whatever provider is registered under the name "oauth" —
+ * with the rest of the URL becoming the action — and would NOT produce the
+ * expected tenant-shaped 302.
+ *
+ * This test configures two providers — one literally named "oauth" (a decoy)
+ * and one named "oac-oauth-tenant" (deliberately containing the substring
+ * "oauth" to also catch over-aggressive stripping) — with distinctive
+ * client_ids, then asserts that /oauth/oac-oauth-tenant/login redirects to
+ * the tenant provider's authorizationUrl with the tenant's client_id. Any
+ * regression that breaks path-segment routing will fail this assertion.
+ */
+import { suite, test, before, after } from 'node:test';
+import { strictEqual } from 'node:assert/strict';
+import { join, dirname } from 'node:path';
+import { createRequire } from 'node:module';
+import { setupHarperWithFixture, teardownHarper, type ContextWithHarper } from '@harperfast/integration-testing';
+
+const require = createRequire(import.meta.url);
+
+function getHarperBinPath(): string {
+	return join(dirname(require.resolve('harper')), 'bin', 'harper.js');
+}
+
+const fixturePath = join(import.meta.dirname, 'fixtures', 'path-segment-routing-app');
+
+const TENANT_CLIENT_ID = 'oauth-tenant-client-id';
+const DECOY_CLIENT_ID = 'decoy-oauth-client-id';
+
+suite('OAuth Resource routes by URL path segment (not literal "oauth")', (ctx: ContextWithHarper) => {
+	before(async () => {
+		await setupHarperWithFixture(ctx, fixturePath, {
+			harperBinPath: getHarperBinPath(),
+			env: {
+				OAUTH_TENANT_CLIENT_ID: TENANT_CLIENT_ID,
+				OAUTH_DECOY_CLIENT_ID: DECOY_CLIENT_ID,
+			},
+			config: { logging: { stdStreams: true } },
+		});
+	});
+
+	after(async () => {
+		await teardownHarper(ctx);
+	});
+
+	test('/oauth/oac-oauth-tenant/login dispatches to the tenant provider', async () => {
+		const response = await fetch(`${ctx.harper.httpURL}/oauth/oac-oauth-tenant/login`, {
+			redirect: 'manual',
+		});
+
+		strictEqual(response.status, 302, `expected 302 redirect, got ${response.status}`);
+		const location = response.headers.get('location');
+		strictEqual(typeof location, 'string', 'Location header missing');
+		const url = new URL(location!);
+
+		// The tenant provider's authorizationUrl is http://tenant.test/authorize;
+		// the decoy's is http://decoy.test/authorize. A parseRoute that returned
+		// "oauth" as providerName would either 404 (action mismatch) or pull
+		// the decoy's client_id — both fail these assertions.
+		strictEqual(url.origin, 'http://tenant.test');
+		strictEqual(url.pathname, '/authorize');
+		strictEqual(
+			url.searchParams.get('client_id'),
+			TENANT_CLIENT_ID,
+			`client_id was ${url.searchParams.get('client_id')} — expected tenant's (${TENANT_CLIENT_ID}), decoy's is ${DECOY_CLIENT_ID}`
+		);
+	});
+});