diff --git a/apps/api/src/lib/git-forwarding/relay.ts b/apps/api/src/lib/git-forwarding/relay.ts
index 87b854228..ae5096b45 100644
--- a/apps/api/src/lib/git-forwarding/relay.ts
+++ b/apps/api/src/lib/git-forwarding/relay.ts
@@ -181,7 +181,11 @@ function handleConnection(
     void getLocalGhToken()
       .then((token) => {
         if (!token) return finish(null, "no-token", meta);
-        // GitHub HTTPS token auth: token as password, any non-empty username.
+        // GitHub HTTPS token auth: it reads the token from either Basic-auth
+        // slot and ignores the other value, so the username here is a label.
+        // URL-form auth picks the pair GitHub documents per token type —
+        // see gitCredentialPair (packages/adapters/src/runtime/git-clone.ts);
+        // this is the credential-helper protocol, not a URL, so it stays put.
         finish(`username=x-access-token\npassword=${token}\n\n`, "granted", meta);
       })
       .catch(() => finish(null, "token-error", meta));
diff --git a/apps/api/src/modules/deployments/build-log-sanitize.ts b/apps/api/src/modules/deployments/build-log-sanitize.ts
index e75912c8f..ab067ef5b 100644
--- a/apps/api/src/modules/deployments/build-log-sanitize.ts
+++ b/apps/api/src/modules/deployments/build-log-sanitize.ts
@@ -43,7 +43,11 @@ export const MAX_TOTAL_CHARS = 4_000_000;
  * Credentials embedded in a URL's userinfo. The shape that matters is the one
  * `injectGitToken` builds for a private clone:
  *
- *   https://x-access-token:<installation-token>@github.com/owner/repo.git
+ *   https://<user-token>:x-oauth-basic@github.com/owner/repo.git   (PAT / OAuth)
+ *   https://x-access-token:<installation-token>@github.com/owner/repo.git   (App)
+ *
+ * Both are matched by userinfo position, not by which slot holds the secret, so a
+ * change to the credential pair cannot quietly stop the redaction from firing.
  *
  * That URL is interpolated into a shell command whose git output is streamed into
  * the persisted build log, so without this the token lands in `build_session.logs`
diff --git a/apps/api/test/modules/deployments/build-log-sanitize.test.ts b/apps/api/test/modules/deployments/build-log-sanitize.test.ts
index 991e55a73..fe3d0941b 100644
--- a/apps/api/test/modules/deployments/build-log-sanitize.test.ts
+++ b/apps/api/test/modules/deployments/build-log-sanitize.test.ts
@@ -237,9 +237,10 @@ describe("sanitizeLogsForPersistence", () => {
 });
 
 /**
- * The deploy pipeline builds `https://x-access-token:<token>@github.com/o/r.git`
- * (injectGitToken, packages/adapters/src/runtime/git-clone.ts:30) and interpolates it
- * into a shell command whose git output is persisted. So the credential is one the
+ * The deploy pipeline builds `https://<token>:x-oauth-basic@github.com/o/r.git` for a
+ * user token and `https://x-access-token:<token>@…` for an App installation token
+ * (injectGitToken / gitCredentialPair, packages/adapters/src/runtime/git-clone.ts) and
+ * interpolates it into a shell command whose git output is persisted. So the credential is one the
  * pipeline manufactures itself — masking project env upstream does nothing for it,
  * and `build_session.logs` outlives the ~60-minute token in backups and exports.
  */
@@ -253,6 +254,15 @@ describe("redactCredentials", () => {
     expect(out).toContain("https://***@github.com/acme/app.git");
   });
 
+  it("redacts the user-token pair — secret in the USERNAME slot", () => {
+    const out = redactCredentials(
+      "Cloning into 'app'... https://ghp_0123456789abcdefghij:x-oauth-basic@github.com/acme/app.git",
+    );
+    expect(out).not.toContain("ghp_0123456789abcdefghij");
+    expect(out).not.toContain("x-oauth-basic");
+    expect(out).toContain("https://***@github.com/acme/app.git");
+  });
+
   it("redacts a token used as the whole userinfo (no colon)", () => {
     const out = redactCredentials("remote: https://ghp_0123456789abcdefghij@github.com/a/b");
     expect(out).not.toContain("ghp_0123456789abcdefghij");
diff --git a/packages/adapters/src/index.ts b/packages/adapters/src/index.ts
index c874e850a..1e7c2395b 100644
--- a/packages/adapters/src/index.ts
+++ b/packages/adapters/src/index.ts
@@ -47,6 +47,7 @@ export {
   sq,
   assembleGitClone,
   injectGitToken,
+  gitCredentialPair,
   toGitHubSshUrl,
   type GitCloneAuth,
   type GitCloneInvocation,
diff --git a/packages/adapters/src/runtime/build-pipeline.ts b/packages/adapters/src/runtime/build-pipeline.ts
index dd5a98c54..91b5f2166 100644
--- a/packages/adapters/src/runtime/build-pipeline.ts
+++ b/packages/adapters/src/runtime/build-pipeline.ts
@@ -17,7 +17,13 @@ import { sq, injectGitToken, assembleGitClone } from "./git-clone";
 import { materializeGitSsh, shellGitSshWriter, type GitSshMaterial } from "./git-ssh-material";
 
 // Re-exported for the docker adapters that import these from here.
-export { sq, injectGitToken, toGitHubSshUrl, assembleGitClone } from "./git-clone";
+export {
+  sq,
+  injectGitToken,
+  gitCredentialPair,
+  toGitHubSshUrl,
+  assembleGitClone,
+} from "./git-clone";
 
 // ─── BuildLogger - single source of truth for step + log events ─────────────
 
diff --git a/packages/adapters/src/runtime/git-clone.test.ts b/packages/adapters/src/runtime/git-clone.test.ts
index 8c54cc2ed..257dbcf68 100644
--- a/packages/adapters/src/runtime/git-clone.test.ts
+++ b/packages/adapters/src/runtime/git-clone.test.ts
@@ -1,5 +1,11 @@
 import { describe, it, expect } from "vitest";
-import { sq, injectGitToken, toGitHubSshUrl, assembleGitClone } from "./git-clone";
+import {
+  sq,
+  injectGitToken,
+  gitCredentialPair,
+  toGitHubSshUrl,
+  assembleGitClone,
+} from "./git-clone";
 
 describe("sq (POSIX single-quote)", () => {
   it("wraps a plain value", () => {
@@ -22,17 +28,23 @@ describe("injectGitToken", () => {
   });
   it("rides a classic PAT in the username slot on github.com", () => {
     expect(injectGitToken("https://github.com/owner/repo.git", "ghp_1234")).toBe(
-      "https://ghp_1234@github.com/owner/repo.git",
+      "https://ghp_1234:x-oauth-basic@github.com/owner/repo.git",
     );
   });
   it("rides a fine-grained PAT in the username slot on github.com", () => {
     expect(injectGitToken("https://github.com/owner/repo.git", "github_pat_1234")).toBe(
-      "https://github_pat_1234@github.com/owner/repo.git",
+      "https://github_pat_1234:x-oauth-basic@github.com/owner/repo.git",
     );
   });
   it("rides an OAuth token in the username slot on github.com", () => {
     expect(injectGitToken("https://github.com/owner/repo.git", "gho_1234")).toBe(
-      "https://gho_1234@github.com/owner/repo.git",
+      "https://gho_1234:x-oauth-basic@github.com/owner/repo.git",
+    );
+  });
+  it("treats a legacy prefix-less PAT as a user token", () => {
+    const legacy = "a".repeat(40);
+    expect(injectGitToken("https://github.com/owner/repo.git", legacy)).toBe(
+      `https://${legacy}:x-oauth-basic@github.com/owner/repo.git`,
     );
   });
   it("keeps x-access-token on non-GitHub hosts (arbitrary username accepted)", () => {
@@ -40,6 +52,21 @@ describe("injectGitToken", () => {
       "https://x-access-token:glpat-1@gitlab.com/owner/repo.git",
     );
   });
+  it("keeps x-access-token on GitHub Enterprise (own domain, not github.com)", () => {
+    expect(injectGitToken("https://github.acme-corp.com/owner/repo.git", "ghp_1234")).toBe(
+      "https://x-access-token:ghp_1234@github.acme-corp.com/owner/repo.git",
+    );
+  });
+  it("trims a pasted token instead of percent-encoding the whitespace", () => {
+    expect(injectGitToken("https://github.com/owner/repo.git", "  ghp_1234\n")).toBe(
+      "https://ghp_1234:x-oauth-basic@github.com/owner/repo.git",
+    );
+  });
+  it("returns the URL unchanged when the token is only whitespace", () => {
+    expect(injectGitToken("https://github.com/owner/repo.git", "   ")).toBe(
+      "https://github.com/owner/repo.git",
+    );
+  });
   it("returns the URL unchanged when no token", () => {
     expect(injectGitToken("https://github.com/owner/repo.git")).toBe(
       "https://github.com/owner/repo.git",
@@ -50,6 +77,43 @@ describe("injectGitToken", () => {
       "git@github.com:owner/repo.git",
     );
   });
+
+  // A URL missing the password is not a complete credential: git sends an empty
+  // password, then on the 401 asks GIT_ASKPASS / the credential helper / the tty
+  // for the real one. Every clone path sets GIT_ASKPASS=/bin/echo, so a path that
+  // forgets it dies with "unable to get password from user" and never surfaces
+  // GitHub's reason. Both slots filled = self-contained on success and failure.
+  it("always emits BOTH Basic-auth slots, whatever the token or host", () => {
+    const tokens = ["ghs_1", "ghp_1", "github_pat_1", "gho_1", "ghu_1", "a".repeat(40), "glpat-1"];
+    const hosts = ["github.com", "github.acme-corp.com", "gitlab.com", "git.example.org"];
+    for (const host of hosts) {
+      for (const token of tokens) {
+        const out = injectGitToken(`https://${host}/owner/repo.git`, token);
+        const { username, password } = new URL(out);
+        expect(username, `${host} / ${token}`).not.toBe("");
+        expect(password, `${host} / ${token}`).not.toBe("");
+        expect(out).toContain(`@${host}/`);
+      }
+    }
+  });
+});
+
+describe("gitCredentialPair", () => {
+  it("carries the token in exactly one slot and a fixed literal in the other", () => {
+    const user = gitCredentialPair("github.com", "ghp_1234");
+    expect(user).toEqual({ username: "ghp_1234", password: "x-oauth-basic" });
+    const app = gitCredentialPair("github.com", "ghs_1234");
+    expect(app).toEqual({ username: "x-access-token", password: "ghs_1234" });
+  });
+  // Suffix-matching the host would pull gist./raw. subdomains into the github.com
+  // branch. Neither is a clone source, and the general form works on both, so the
+  // test is an exact host match on purpose.
+  it("matches github.com exactly — subdomains take the general form", () => {
+    expect(gitCredentialPair("gist.github.com", "ghp_1234")).toEqual({
+      username: "x-access-token",
+      password: "ghp_1234",
+    });
+  });
 });
 
 describe("toGitHubSshUrl", () => {
@@ -74,7 +138,7 @@ describe("assembleGitClone — token / public mode", () => {
     gitToken: "ghp_1234",
   });
   it("injects the token into the clone URL (PAT as username on github.com)", () => {
-    expect(inv.cloneUrl).toBe("https://ghp_1234@github.com/owner/repo.git");
+    expect(inv.cloneUrl).toBe("https://ghp_1234:x-oauth-basic@github.com/owner/repo.git");
   });
   it("fails fast instead of prompting (no interactive credential path)", () => {
     expect(inv.gitEnv).toContain("GIT_TERMINAL_PROMPT=0");
diff --git a/packages/adapters/src/runtime/git-clone.ts b/packages/adapters/src/runtime/git-clone.ts
index 8e6b4bbac..e8ca541fc 100644
--- a/packages/adapters/src/runtime/git-clone.ts
+++ b/packages/adapters/src/runtime/git-clone.ts
@@ -23,31 +23,52 @@ export function sq(value: string): string {
 }
 
 /**
- * Inject a token into an HTTPS git URL for private repo access.
+ * The Basic-auth pair for a git HTTPS credential.
  *
- * On GitHub the username is not free-form: `x-access-token` is accepted only
- * for GitHub App installation tokens (ghs_…). A classic or fine-grained PAT
- * (ghp_…, github_pat_…, gho_…) behind a fixed `x-access-token` username is
- * rejected with "Invalid username or token", so those credentials ride in
- * the username slot instead:
- *   https://github.com/owner/repo.git → https://ghp_<token>@github.com/owner/repo.git
- * Other hosts keep the previous form (x-access-token:<token>@), which they
- * accept with an arbitrary username.
- * Unchanged when no token or the URL isn't HTTPS.
+ * Both slots are ALWAYS filled. `https://<token>@host` is not a complete
+ * credential to git: it sends an empty password, and on the 401 goes looking for
+ * the real one — GIT_ASKPASS, then the credential helper, then the tty. Every
+ * clone path here sets `GIT_ASKPASS=/bin/echo`, so today that detour ends in a
+ * retry with garbage; a path that forgets to set it fails with git's "unable to
+ * get password from user" before it ever authenticates, hiding GitHub's actual
+ * reason. Filling both slots keeps the URL self-contained on success AND failure.
+ *
+ * Which slot holds the token does not matter to GitHub — it reads the token from
+ * either and ignores the other value. So each token type gets the pair GitHub
+ * itself documents: `x-access-token:<token>` for App installation tokens,
+ * `<token>:x-oauth-basic` for user tokens (PAT classic, fine-grained, OAuth).
+ */
+export function gitCredentialPair(
+  hostname: string,
+  token: string,
+): { username: string; password: string } {
+  // Exact host, not a suffix match. Every other host — GitHub Enterprise on its
+  // own domain, GitLab, Gitea — takes the x-access-token form, which works
+  // wherever an arbitrary username is accepted. Narrowing this test can only
+  // route a host to the general form, never strand one without a credential.
+  if (hostname === "github.com" && !token.startsWith("ghs_")) {
+    return { username: token, password: "x-oauth-basic" };
+  }
+  return { username: "x-access-token", password: token };
+}
+
+/**
+ * Inject a token into an HTTPS git URL for private repo access:
+ *   https://github.com/owner/repo.git
+ *     → https://<token>:x-oauth-basic@github.com/owner/repo.git
+ * Unchanged when there is no token or the URL isn't HTTPS.
  */
 export function injectGitToken(repoUrl: string, token?: string): string {
-  if (!token) return repoUrl;
+  // Trim first: a token pasted with surrounding whitespace percent-encodes into
+  // the URL (%20…%20) and fails auth for a reason no log makes visible.
+  const secret = token?.trim();
+  if (!secret) return repoUrl;
   try {
     const url = new URL(repoUrl);
     if (url.protocol !== "https:") return repoUrl;
-    const isGitHub = /(^|\.)github\.com$/.test(url.hostname);
-    if (isGitHub && !token.startsWith("ghs_")) {
-      url.username = token;
-      url.password = "";
-    } else {
-      url.username = "x-access-token";
-      url.password = token;
-    }
+    const { username, password } = gitCredentialPair(url.hostname, secret);
+    url.username = username;
+    url.password = password;
     return url.toString();
   } catch {
     return repoUrl;