diff --git a/apps/server/src/project/ProjectSetupScriptRunner.test.ts b/apps/server/src/project/ProjectSetupScriptRunner.test.ts
index 4eb466200bc90..eb94f348e7a50 100644
--- a/apps/server/src/project/ProjectSetupScriptRunner.test.ts
+++ b/apps/server/src/project/ProjectSetupScriptRunner.test.ts
@@ -41,6 +41,7 @@ const makeHarness = Effect.fn(function* (options: {
   readonly history?: string;
   readonly opening?: Deferred.Deferred<void>;
   readonly shell?: string | null;
+  readonly command?: string;
 }) {
   const listeners = new Set<(event: TerminalEvent) => Effect.Effect<void>>();
   const writes = yield* Queue.unbounded<string>();
@@ -88,7 +89,7 @@ const makeHarness = Effect.fn(function* (options: {
         {
           id: "setup",
           name: "Setup",
-          command: "vp i",
+          command: options.command ?? "vp i",
           icon: "configure",
           runOnWorktreeCreate: true,
         },
@@ -104,6 +105,7 @@ const setup = Effect.fn(function* (
   options: {
     readonly history?: string;
     readonly shell?: string | null;
+    readonly command?: string;
   } = {},
 ) {
   const harness = yield* makeHarness(options);
@@ -123,6 +125,20 @@ describe("ProjectSetupScriptRunner", () => {
     }),
   );
 
+  it.effect("a fish setup command that fails to parse still reports completion", () =>
+    Effect.gen(function* () {
+      const command = 'node "${HOME:-.}/x.mjs" setup';
+      const { writes } = yield* setup({ shell: "/usr/bin/fish", command });
+      yield* TestClock.adjust("3 seconds");
+      const [check, ...rest] = (yield* Queue.take(writes)).split("\r");
+      expect(check).toContain(
+        `'node "\${HOME:-.}/x.mjs" setup' | '/usr/bin/fish' --no-config --no-execute; or printf`,
+      );
+      // Typed on its own line so the fish line editor still expands abbreviations.
+      expect(rest).toContain(command);
+    }),
+  );
+
   it.effect("shows a startup prompt and types only once the line editor starts", () =>
     Effect.gen(function* () {
       const { result, writes, outputLines, emit } = yield* setup();
diff --git a/apps/server/src/project/ProjectSetupScriptRunner.ts b/apps/server/src/project/ProjectSetupScriptRunner.ts
index 8e7c3105b36bc..bc6f978938f14 100644
--- a/apps/server/src/project/ProjectSetupScriptRunner.ts
+++ b/apps/server/src/project/ProjectSetupScriptRunner.ts
@@ -176,10 +176,17 @@ function resolveCompletionShell(shell: string): CompletionShell | null {
   return "posix";
 }
 
+function quoteFish(value: string): string {
+  return `'${value.replace(/[\\']/g, "\\$&")}'`;
+}
+
 // A block with its own closing line protects the sentinel from trailing comments, heredocs and scripts reading stdin.
+// Interactive fish leaves a body that fails to parse in its editor, so it is parse-checked first, except on fish
+// before 3.3 (no --no-config) or when it uses an abbreviation, which only the editor expands.
 function wrapCommandForCompletion(
   command: string,
   shell: CompletionShell,
+  shellPath: string,
   sentinel: string,
 ): string {
   const body = command.replace(/\r?\n/g, "\r");
@@ -187,7 +194,14 @@ function wrapCommandForCompletion(
     case "powershell":
       return `$global:LASTEXITCODE = $null; & {\r${body}\r}; if ($null -ne $LASTEXITCODE) { $__t3c = $LASTEXITCODE } elseif ($?) { $__t3c = 0 } else { $__t3c = 1 }; Write-Host "${sentinel}$__t3c"`;
     case "fish":
-      return `begin\r${body}\rend; printf '\\n${sentinel}%s\\n' $status`;
+      return [
+        "begin; if string match -qr '^(3\\.([3-9]|[1-9][0-9])|[4-9]|[1-9][0-9])\\.' -- $version",
+        "and not abbr --show | string match -q -- '* --regex *'",
+        "set -l a (abbr --list | string escape --style=regex)",
+        `if test (count $a) -eq 0; or not string match -qr -- '(^|[\\s;|&(])('(string join '|' -- $a)')($|[\\s;|&)])' ${quoteFish(body)}`,
+        `printf '%s' ${quoteFish(body)} | ${quoteFish(shellPath)} --no-config --no-execute; or printf '\\n${sentinel}%s\\n' $status`,
+        `end; end; end\rbegin\r${body}\rend; printf '\\n${sentinel}%s\\n' $status`,
+      ].join("; ");
     case "posix":
       return `( ${body}\r); printf '\\n${sentinel}%s\\n' "$?"`;
   }
@@ -500,6 +514,7 @@ export const make = Effect.gen(function* () {
         commandLine = wrapCommandForCompletion(
           script.command,
           completionShell,
+          shell,
           completionSentinel(completionToken),
         );
       }