# iter cli-diag-human — non-JSON CLI surfaces `WorkspaceLoadError` with bracketed `[code]`

**Date:** 2026-05-14
**Started from:** 6755060 (post-rpe.1.tidy)
**Status:** DONE

## Summary

Closes the P2 todo "CLI human-mode diagnostic surface for
`WorkspaceLoadError`" surfaced by the ct.1.8 tester (2026-05-11).
Pre-iter, the non-JSON path of every CLI subcommand that called
`ailang_surface::load_workspace(&path)?` propagated the error via
anyhow's Display — producing `Error: <thiserror-formatted-message>`
on stderr — while the JSON path of `ail check --json` correctly
routed through `workspace_error_to_diagnostic` and emitted the
bracketed `[code]` prefix. The asymmetry made the human-mode
output harder to triage and less consistent across the toolchain.

Fix: new private helper `load_workspace_human(path) -> Result<Workspace>`
in `crates/ail/src/main.rs` that wraps `ailang_surface::load_workspace`,
threads any `WorkspaceLoadError` through the existing
`workspace_error_to_diagnostic`, formats the resulting `Diagnostic`
into a single stderr line of shape
`error: [<code>] <def>: <message>`, and exits non-zero. Pure I/O
errors (where `workspace_error_to_diagnostic` returns `None` per
the loader's own contract) still propagate as anyhow errors so the
caller's `?`-flow stays well-behaved.

Nine call sites in `main.rs` swapped from
`ailang_surface::load_workspace(<expr>)?` to
`load_workspace_human(<expr>)?`: the `ail check` (non-JSON arm),
`build`, `run`, `emit-ir`, `prose`, `describe`, `deps`, `diff`,
`manifest` paths. The JSON arm of `ail check` (line 596) kept its
explicit `match` shape — it builds a structured diagnostics array
on stdout, which is a different output contract.

The `BareCrossModuleTypeRef` arm of `workspace_error_to_diagnostic`
gained the existing migration-command hint
("Run `ail migrate-canonical-types` to fix legacy fixtures.") so
that the ct.1.8 actionable-hint test
(`check_human_mode_emits_actionable_message_to_stderr`) stays
green. The hint was previously carried by `WorkspaceLoadError`'s
thiserror Display impl; making `workspace_error_to_diagnostic` the
single source for both JSON and human paths required moving it
into the Diagnostic message body.

## Files touched

- `crates/ail/src/main.rs` — new `load_workspace_human` helper
  (~25 lines, including doc comment); 9 call-site swaps; one
  Diagnostic message gained the migration-hint suffix.
- `crates/ail/tests/cli_diag_human_workspace_load_error.rs` —
  new RED-pin test (tempdir-based fixture asserting
  `[module-not-found]` in stderr on a missing-import workspace).
- `docs/roadmap.md` — entry struck through.

## Verification

- RED test `check_non_json_emits_bracketed_module_not_found`
  flipped from RED to GREEN.
- `cargo test --workspace` → 565 / 0 / 3 (was 564 pre-iter; +1
  from this iter's RED pin).
- `cargo clippy --workspace --all-targets` → 0 warnings.
- `cargo doc --workspace --no-deps` → 0 warnings.

## Concerns

- (none)

## Known debt

- (none)
