## Code Analysis

### The retained shell contract requires a structured failure result
`scripts/test-job-runner-image.sh:59-79`
```sh
./zig-out/bin/boris-job-runner --once \
  --boris ./zig-out/bin/boris \
  --archive "$OUT/poisoned.tar" \
  --result-json "$OUT/poisoned.json" \
  --work-root "$OUT/ws"
poisoned_rc=$?
[[ "$poisoned_rc" -eq 1 ]] || fail "poisoned job exited $poisoned_rc, expected 1"
[[ -f "$OUT/poisoned.json" ]] || fail "poisoned.json not written"
```
The same script then reads the result and requires `ok: false`, `runnerClass: "content"`, no artifacts, and an `EPARENTMISSING` diagnostic (`scripts/test-job-runner-image.sh:70-76`).

### The native path renders and writes the result before returning the failure code
`src/job_runner.zig:547-602`
```zig
const ok = class == .ok and exit_code == 0 and !oversize;
if (!ok) {
    for (artifacts) |a| {
        gpa.free(a.path);
        gpa.free(a.bytes);
    }
    gpa.free(artifacts);
    artifacts = try gpa.alloc(Artifact, 0);
}

return .{
    .ok = ok,
    .runner_class = if (ok) .ok else class,
    .exit_code = exit_code,
    .diagnostics = parsed.diagnostics,
    .artifacts = artifacts,
    .workspace_removed = true,
};
```
For the invalid content case, this constructs a failed structured `JobResult` and clears artifacts rather than discarding the diagnostic payload.

`src/job_runner.zig:1179-1200`
```zig
const json = renderResultJson(gpa, result) catch return 3;
defer gpa.free(json);

if (cli.result_json_path) |path| {
    if (std.fs.path.dirname(path)) |parent| {
        if (parent.len > 0) cwd.createDirPath(io, parent) catch {};
    }
    cwd.writeFile(io, .{ .sub_path = path, .data = json }) catch |err| {
        std.debug.print("error: write result json: {s}\n", .{@errorName(err)});
        return 3;
    };
}

return result.runner_class.processExit();
```
The caller is expected to write the rendered JSON to `--result-json` and only then return the runner-class exit code. The observed missing file means the executed invalid-content path did not deliver the artifact required by its shell contract.

### Observed execution
The retained script built the native binaries and produced a valid result for the valid fixture before invoking the missing-parent fixture:

```text
+ zig build -Doptimize=ReleaseSafe
==> valid fixture through native --once
+ ./zig-out/bin/boris-job-runner --once --boris ./zig-out/bin/boris --archive /workspaces/repo/.zig-cache/job-runner-smoke/valid.tar --result-json /workspaces/repo/.zig-cache/job-runner-smoke/valid.json --work-root /workspaces/repo/.zig-cache/job-runner-smoke/ws
valid ok, artifacts 11
```

The invalid-content invocation returned the expected status, but the required result file was missing:

```text
==> poisoned fixture through native --once
+ ./zig-out/bin/boris-job-runner --once --boris ./zig-out/bin/boris --archive /workspaces/repo/.zig-cache/job-runner-smoke/poisoned.tar --result-json /workspaces/repo/.zig-cache/job-runner-smoke/poisoned.json --work-root /workspaces/repo/.zig-cache/job-runner-smoke/ws
+ poisoned_rc=1
+ [[ 1 -eq 1 ]]
+ [[ -f /workspaces/repo/.zig-cache/job-runner-smoke/poisoned.json ]]
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
FileNotFoundError: [Errno 2] No such file or directory: '/workspaces/repo/.zig-cache/job-runner-smoke/poisoned.json'
```

The static absence check found no deleted contract-claim/build-integration invocation; its retained matches were ordinary `zig build` references in the shell checks and build files.

### Result
The captured run supports the reported failure: invalid content exits with status `1`, but the caller-required `poisoned.json` result payload is not available for inspection.

### Test context
The overall retained shell suite also encountered unrelated existing checks, but this attachment focuses on the concrete job-runner result-file failure and the source path that is expected to write it.