diff --git a/changelog/unreleased/1577.md b/changelog/unreleased/1577.md
new file mode 100644
index 000000000..da8a9b936
--- /dev/null
+++ b/changelog/unreleased/1577.md
@@ -0,0 +1,3 @@
+- **BREAKING CHANGES:** `djs`: `fjs compile` exits with code `1` instead of `0`
+  when the input cannot be read or fails to parse, so a failed compile is
+  detectable from the exit status
diff --git a/fjs/djs/module.f.mjs b/fjs/djs/module.f.mjs
index 4cbb35737..c8b251e42 100644
--- a/fjs/djs/module.f.mjs
+++ b/fjs/djs/module.f.mjs
@@ -18,7 +18,16 @@ import { writeUtf8File, error } from '../effects/node/module.f.mjs'
 
 /** @typedef {ReadFile | WriteFile | Write} _CompileOp */
 
-/** @type {(args: readonly string[]) => Effect<_CompileOp, number>} */
+/**
+ * Compiles the DJS module `args[0]` into `args[1]`, serializing as a JSON tree
+ * when the output name ends with `.json` and as a module otherwise.
+ *
+ * Returns the process exit code: `0` once the output file is written, `1` on
+ * every failure — too few arguments, a missing input file, or a parse error —
+ * so a caller can detect a failed compile from the exit status alone.
+ *
+ * @type {(args: readonly string[]) => Effect<_CompileOp, number>}
+ */
 export const compile = args => {
     if (args.length < 2) {
         return step(
@@ -35,7 +44,7 @@ export const compile = args => {
                 const metadata = result[1].metadata
                 return step(
                     error(`${metadata?.path}:${metadata?.line}:${metadata?.column} - error: ${result[1].message}`),
-                    () => pure(0))
+                    () => pure(1))
             }
             const content = outputFileName.endsWith('.json')
                 ? stringifyAsTree(sort)(result[1])
diff --git a/fjs/djs/proof.f.mjs b/fjs/djs/proof.f.mjs
index 37d346efa..89a2ad819 100644
--- a/fjs/djs/proof.f.mjs
+++ b/fjs/djs/proof.f.mjs
@@ -43,13 +43,15 @@ export const proof = {
     },
     fileNotFound: () => {
         const [state, code] = virtual(emptyState)(compile(['missing.f.js', 'output.f.js']))
-        assertEq(code, 0)
+        assertEq(code, 1)
         assert(state.stderr.includes('file not found'), state.stderr)
+        assertEq(state.root['output.f.js'], undefined)
     },
     parseError: () => {
         const root = { 'bad.f.js': [utf8('export default @')] }
         const [state, code] = virtual({ ...emptyState, root })(compile(['bad.f.js', 'output.f.js']))
-        assertEq(code, 0)
+        assertEq(code, 1)
         assert(state.stderr !== '', 'expected error output')
+        assertEq(state.root['output.f.js'], undefined)
     },
 }
diff --git a/fjs/djs/todo/compile-error-exit-code.md b/fjs/djs/todo/compile-error-exit-code.md
deleted file mode 100644
index 2d0bfc851..000000000
--- a/fjs/djs/todo/compile-error-exit-code.md
+++ /dev/null
@@ -1,43 +0,0 @@
-# `fjs compile` exits 0 on a parse error
-
-**Priority:** P2
-**Status:** open
-
-## Problem
-
-When compilation fails, `compile` in `fjs/djs/module.f.mjs` prints the error
-message but then returns `pure(0)`, so the process exits with code 0:
-
-```js
-if (result[0] === 'error') {
-    const metadata = result[1].metadata
-    return step(
-        error(`${metadata?.path}:${metadata?.line}:${metadata?.column} - error: ${result[1].message}`),
-        () => pure(0))
-}
-```
-
-The argument-count check just above correctly returns `pure(1)`, so this branch
-is the odd one out. As a result, scripts and CI cannot detect a failed compile
-from the exit status:
-
-```sh
-$ printf 'console.log("hi")\nexport default 1\n' > x.f.mjs
-$ fjs compile x.f.mjs out.mjs; echo $?
-x.f.mjs:1:1 - error: const not found
-0
-```
-
-The output file is (correctly) not written in this case, so the only failure
-signal is the message text.
-
-## Fix
-
-Return `pure(1)` from the parse-error branch. Check whether any caller or test
-depends on the current exit code.
-
-## Related
-
-- `file not found` errors from `transpile` take the same branch and are also
-  reported with exit code 0 (and with `undefined:undefined:undefined` as the
-  location, since `metadata` is `null` — a second, cosmetic issue).
diff --git a/fjs/djs/todo/parse-error-location-format.md b/fjs/djs/todo/parse-error-location-format.md
new file mode 100644
index 000000000..115e81058
--- /dev/null
+++ b/fjs/djs/todo/parse-error-location-format.md
@@ -0,0 +1,62 @@
+## parse-error-location-format. `compile`: `undefined:undefined:undefined` when a `ParseError` has no metadata
+
+**Priority:** P4
+**Status:** open
+
+### Problem
+
+`compile` in `fjs/djs/module.f.mjs` formats every `ParseError` as
+`<path>:<line>:<column> - error: <message>`, reading the three fields off
+`result[1].metadata`:
+
+```js
+const metadata = result[1].metadata
+return step(
+    error(`${metadata?.path}:${metadata?.line}:${metadata?.column} - error: ${result[1].message}`),
+    () => pure(1))
+```
+
+`ParseError.metadata` is `TokenMetadata | null`, and the transpiler raises two
+errors with no token to point at — `file not found` (`transpiler/module.f.mjs:41`)
+and `circular dependency` (`:80`) — both of which carry `metadata: null`. The
+optional chaining then prints the literal string `undefined` three times:
+
+```sh
+$ fjs compile nope.f.mjs out.mjs
+undefined:undefined:undefined - error: file not found
+```
+
+The exit code is correct (`1`); only the location prefix is wrong. It is noise
+for a human and a trap for anything parsing the line as `path:line:column`.
+
+### Proposal
+
+Emit the prefix only when there is a location to report:
+
+```js
+const { metadata, message } = result[1]
+const location = metadata === null
+    ? ''
+    : `${metadata.path}:${metadata.line}:${metadata.column} - `
+return step(error(`${location}error: ${message}`), () => pure(1))
+```
+
+A metadata-less error then reads `error: file not found`. An alternative worth
+weighing first: give these two errors real metadata — the importing module's
+path is known at both sites — which fixes the message *and* tells the user which
+import failed. That is the better output but a larger change, since
+`TokenMetadata` also wants a line and column.
+
+### Tasks
+
+- [ ] Pick one of the two shapes above and implement it.
+- [ ] Assert the exact `stderr` text in `fjs/djs/proof.f.mjs`'s `fileNotFound`,
+      and cover the metadata-carrying branch too.
+- [ ] `npx tsc` clean; `fjs t` passes.
+
+### Related
+
+- `fjs/djs/module.f.mjs` — the formatting site.
+- `fjs/djs/transpiler/module.f.mjs:41`, `:80` — the two `metadata: null` errors.
+- Split out of the `compile` exit-code issue, which fixed the exit status of
+  this same branch and left the cosmetic half open.