Enforces the Step 1b §1.4 widget boundary invariant: widget logic
(Widget impls + layout/paint/access_node methods) lives in
crates/openpencil-shell-core/src/widgets/; shell-web's only
widget-touching file is `widget_host.rs` and even there the only
widget-method signature allowed is the `// glue:` marked paint
dispatcher.
Forward checks (no widget logic in shell-web/src/):
- F1: `impl(<...>)?[[:space:]]+(ns::)*Widget[[:space:]]+for[[:space:]]`
anywhere under shell-web/src/. Allows generic params + arbitrary
namespace depth so `impl<T> shell_core::widgets::Widget for X` is
caught. No `// glue:` exemption — Widget impls have no place in
shell-web period.
- F2: `fn[[:space:]]+(layout|access_node)\(` anywhere under
shell-web/src/. No exemption.
- F3: `fn[[:space:]]+paint\(` under shell-web/src/, EXCEPT lines in
widget_host.rs that ALSO carry `// glue:`. Tight exemption — the
marker only blesses one specific signature, not arbitrary tagged
lines.
- F4: any line under shell-web/src/ mentioning both
`openpencil_shell_core` AND `widgets`, except widget_host.rs.
Catches direct + grouped `use` forms (e.g. `use
openpencil_shell_core::{widgets::TreeWidget};`) plus path
expressions. Multi-line braced `use` is out of scope (single-line
policy in this crate).
Reverse check (shell-core/src/widgets/ has all four impls):
- R1: For each of {tree, prop_row, dropdown, text_input}, the file
must exist AND, after stripping `//` line comments, must contain
a live `impl Widget for X`. Block comments out of scope (line
comments only in this directory).
CI integration:
- New "Verify Step 1b widget boundary (spec §1.4)" step in
.github/workflows/rust-check.yml right after the existing
"Verify Jian boundary invariants" step, gated to Linux runner
(matches the jian-boundaries pattern).
- Added `tools/check-jian-boundaries.sh` and
`tools/check-widget-boundary.sh` to the rust-check.yml push +
pull_request path filters so PRs editing only the checker still
trigger CI.
7-test regression matrix (positive + 6 negative cases):
- positive (real codebase) → PASS
- generic `impl<T> Widget for X` injected → FAIL F1
- direct `use openpencil_shell_core::widgets` outside host → FAIL F4
- `// glue:` tag on `impl Widget for X` line → FAIL F1 (exemption
doesn't save it; only `fn paint` lines are exempted)
- shell-core file replaced with `// stub` → FAIL R1
- grouped `use openpencil_shell_core::{widgets::TreeWidget};` → FAIL F4
- grouped `use openpencil_shell_core::{widgets};` → FAIL F4
- shell-core file body replaced with `// impl Widget for X { ... }` → FAIL R1
Codex iterate review: 5 rounds → GO. Round 1 BLOCK (greedy
WidgetHost match), R2 BLOCK + 3 CONCERN (calls/imports unchecked,
generic impls, broad exemption, filename-only count), R3 BLOCK +
CONCERN (grouped imports, commented-out impls), R4 2 NITs
(documentation parity), R5 GO clean.
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