diff --git a/apps/server/src/git/GitManager.test.ts b/apps/server/src/git/GitManager.test.ts
index bb7f91ffc39..c06915c51b9 100644
--- a/apps/server/src/git/GitManager.test.ts
+++ b/apps/server/src/git/GitManager.test.ts
@@ -2757,6 +2757,65 @@ it.layer(GitManagerTestLayer)("GitManager", (it) => {
     }),
   );
 
+  it.effect("preserves both branch materialization failures when the fallback also fails", () =>
+    Effect.gen(function* () {
+      const repoDir = yield* makeTempDir("t3code-git-manager-");
+      yield* initRepo(repoDir);
+      const originDir = yield* createBareRemote();
+      yield* runGit(repoDir, ["remote", "add", "origin", originDir]);
+      yield* runGit(repoDir, ["push", "-u", "origin", "main"]);
+
+      const missingForkDir = NodePath.join(repoDir, "missing-fork.git");
+      const { manager } = yield* makeManager({
+        ghScenario: {
+          pullRequest: {
+            number: 93,
+            title: "Missing fork branch",
+            url: "https://github.com/pingdotgg/codething-mvp/pull/93",
+            baseRefName: "main",
+            headRefName: "feature/missing-fork-branch",
+            state: "open",
+            isCrossRepository: true,
+            headRepositoryNameWithOwner: "octocat/codething-mvp",
+            headRepositoryOwnerLogin: "octocat",
+          },
+          repositoryCloneUrls: {
+            "octocat/codething-mvp": {
+              url: missingForkDir,
+              sshUrl: missingForkDir,
+            },
+          },
+        },
+      });
+
+      const error = yield* preparePullRequestThread(manager, {
+        cwd: repoDir,
+        reference: "93",
+        mode: "worktree",
+      }).pipe(Effect.flip);
+
+      if (error._tag !== "GitPullRequestMaterializationError") {
+        return yield* Effect.die(error);
+      }
+      expect(error).toMatchObject({
+        cwd: repoDir,
+        pullRequestNumber: 93,
+        headRepository: "octocat/codething-mvp",
+        headBranch: "feature/missing-fork-branch",
+        localBranch: "t3code/pr-93/feature/missing-fork-branch",
+      });
+      if (!(error.cause instanceof AggregateError)) {
+        return yield* Effect.die(error.cause);
+      }
+      expect(error.cause.errors).toHaveLength(2);
+      expect(error.cause.errors).toEqual([
+        expect.objectContaining({ _tag: "GitCommandError" }),
+        expect.objectContaining({ _tag: "GitCommandError" }),
+      ]);
+      expect(error.cause.cause).toBe(error.cause.errors[0]);
+    }),
+  );
+
   it.effect("launches setup only when creating a new PR worktree", () =>
     Effect.gen(function* () {
       const repoDir = yield* makeTempDir("t3code-git-manager-");
diff --git a/apps/server/src/git/GitManager.ts b/apps/server/src/git/GitManager.ts
index 46da2e6c1f9..f1fb03e7e45 100644
--- a/apps/server/src/git/GitManager.ts
+++ b/apps/server/src/git/GitManager.ts
@@ -41,7 +41,7 @@ import {
   type ChangeRequestTerminology,
 } from "@t3tools/shared/sourceControl";
 
-import { GitManagerError } from "@t3tools/contracts";
+import { GitManagerError, GitPullRequestMaterializationError } from "@t3tools/contracts";
 import * as TextGeneration from "../textGeneration/TextGeneration.ts";
 import * as ProjectSetupScriptRunner from "../project/ProjectSetupScriptRunner.ts";
 import { extractBranchNameFromRemoteRef } from "./remoteRefs.ts";
@@ -631,9 +631,12 @@ export const make = Effect.gen(function* () {
   ) =>
     configurePullRequestHeadUpstreamBase(cwd, pullRequest, localBranch).pipe(
       Effect.catch((error) =>
-        Effect.logWarning(
-          `GitManager.configurePullRequestHeadUpstream: failed to configure upstream for ${localBranch} -> ${pullRequest.headBranch} in ${cwd}: ${error.message}`,
-        ).pipe(Effect.asVoid),
+        Effect.logWarning("GitManager.configurePullRequestHeadUpstream failed", {
+          cwd,
+          localBranch,
+          headBranch: pullRequest.headBranch,
+          cause: error,
+        }).pipe(Effect.asVoid),
       ),
     );
 
@@ -691,12 +694,30 @@ export const make = Effect.gen(function* () {
     localBranch = pullRequest.headBranch,
   ) =>
     materializePullRequestHeadBranchBase(cwd, pullRequest, localBranch).pipe(
-      Effect.catch(() =>
-        gitCore.fetchPullRequestBranch({
-          cwd,
-          prNumber: pullRequest.number,
-          branch: localBranch,
-        }),
+      Effect.catch((primaryCause) =>
+        gitCore
+          .fetchPullRequestBranch({
+            cwd,
+            prNumber: pullRequest.number,
+            branch: localBranch,
+          })
+          .pipe(
+            Effect.mapError(
+              (fallbackCause) =>
+                new GitPullRequestMaterializationError({
+                  cwd,
+                  pullRequestNumber: pullRequest.number,
+                  headRepository: resolveHeadRepositoryNameWithOwner(pullRequest),
+                  headBranch: pullRequest.headBranch,
+                  localBranch,
+                  cause: new AggregateError(
+                    [primaryCause, fallbackCause],
+                    `Repository-head and pull-request-ref fetches both failed for pull request #${pullRequest.number}.`,
+                    { cause: primaryCause },
+                  ),
+                }),
+            ),
+          ),
       ),
     );
   const fileSystem = yield* FileSystem.FileSystem;
@@ -1452,9 +1473,11 @@ export const make = Effect.gen(function* () {
         })
         .pipe(
           Effect.catch((error) =>
-            Effect.logWarning(
-              `GitManager.preparePullRequestThread: failed to launch worktree setup script for thread ${input.threadId} in ${worktreePath}: ${error.message}`,
-            ).pipe(Effect.asVoid),
+            Effect.logWarning("GitManager.preparePullRequestThread setup script failed", {
+              threadId: input.threadId,
+              worktreePath,
+              cause: error,
+            }).pipe(Effect.asVoid),
           ),
         );
     };
diff --git a/packages/contracts/src/git.ts b/packages/contracts/src/git.ts
index 0f1f09729be..aa5cdf8432b 100644
--- a/packages/contracts/src/git.ts
+++ b/packages/contracts/src/git.ts
@@ -361,8 +361,25 @@ export class GitManagerError extends Schema.TaggedErrorClass<GitManagerError>()(
   }
 }
 
+export class GitPullRequestMaterializationError extends Schema.TaggedErrorClass<GitPullRequestMaterializationError>()(
+  "GitPullRequestMaterializationError",
+  {
+    cwd: TrimmedNonEmptyStringSchema,
+    pullRequestNumber: PositiveInt,
+    headRepository: Schema.NullOr(TrimmedNonEmptyStringSchema),
+    headBranch: TrimmedNonEmptyStringSchema,
+    localBranch: TrimmedNonEmptyStringSchema,
+    cause: Schema.Defect(),
+  },
+) {
+  override get message(): string {
+    return `Failed to materialize pull request #${this.pullRequestNumber} branch ${this.headBranch} as ${this.localBranch}.`;
+  }
+}
+
 export const GitManagerServiceError = Schema.Union([
   GitManagerError,
+  GitPullRequestMaterializationError,
   GitCommandError,
   SourceControlProviderError,
   TextGenerationError,