test(build): prove public inspection contracts

Exercise file and source diagnostics, generated targets, Hemlate-derived context facts, missing-file propagation, and invalid Rust context through hemx-build's public inspection API; classify only the currently infallible hemplate parser seam.

req: diagnostics/004

req: diagnostics/006

req: surface/008

req: test/021

.cargo/mutants.toml

@@ -8,6 +8,8 @@
 # - Infallible header parsing and multipart byte collection: adjacent public tests
 #   prove exact ETag/runtime headers and streamed multipart errors; unwrap mutants
 #   are behaviorally equivalent at these validated boundaries.
+# - hemx-build source inspection delegates to hemplate's currently infallible
+#   Surface parser; file I/O and invalid Rust-context errors remain explicitly proven.
 exclude_re = [
   "test_process_try_wait",
   "test_process_poll_delay",
@@ -20,4 +22,7 @@ exclude_re = [
   "replace String::from_utf8.* with String::from_utf8.*unwrap\\(\\) in InteractionForm::parse_multipart",
   "replace HeaderValue::from_str.*runtime_js_hash.* with HeaderValue::from_str.*unwrap\\(\\) in <impl IntoResponse for RuntimeJs>::into_response",
   'replace "runtime hash is a valid ETag" with "" in <impl IntoResponse for RuntimeJs>::into_response',
+  "replace surface_for_heml_source.* with surface_for_heml_source.*unwrap\\(\\) in diagnostics_for_heml_source",
+  "replace surface_for_heml_source.* with surface_for_heml_source.*unwrap\\(\\) in generated_targets_for_heml_source",
+  "replace surface_for_heml_source.* with surface_for_heml_source.*unwrap\\(\\) in template_context_facts_for_heml_source",
 ]

PLAN.md

@@ -21,7 +21,7 @@
 - [ ] **State:** In progress — the package-native capped xtask entry point is reachable, rejects unknown packages, propagates mutest failure, and mutation-tests `hemx-axum`, `hemx-core`, `hemx-js`, and the full `hemx-test` package cleanly; full package closure remains.
 - **User value:** maintainers can run one bounded repository command and trust that meaningful Rust logic across every mutation-applicable library is either killed or explicitly justified.
 - **Build:** add a capped `hemx-xtask` mutation command that invokes `/opt/repositories/mutest`/`mutest` through package-native test targets rather than the broken workspace-wide example path; enumerate only current mutation-applicable library/proc-macro packages; finish adversarial tests or simplify code until every survivor is classified; keep equivalent, invariant-only, and infrastructure-inapplicable classifications inspectable and minimal; document the exact local release command in the existing readiness surface.
-- **Blocked by:** none; broad survivors currently remain in `hemx-build`, `hemx-derive`, and `hemx-lsp` outside already-clean focused contracts. The current `hemx-build` slice now adversarially proves policy, client-module/event/state, confirmation, SSE, delay, throttle, and mixed-event diagnostics; remaining generated-resource and diagnostic-contract survivors remain. The complete 470-mutant `hemx-axum` package gate now passes with 262 caught and 208 unviable after public page/form/multipart/registry/response/runtime proofs and narrow classification of infallible header parsing and streamed multipart unwrap-equivalent mutants.
+- **Blocked by:** none; broad survivors currently remain in `hemx-build`, `hemx-derive`, and `hemx-lsp` outside already-clean focused contracts. The current `hemx-build` frontier now adversarially proves static convention diagnostics plus public file/source diagnostics, generated-target extraction, Hemlate-derived context facts, missing-file propagation, and invalid Rust-context diagnostics mutation-clean; remaining generated-resource and internal diagnostic survivors remain. The complete 470-mutant `hemx-axum` package gate now passes with 262 caught and 208 unviable after public page/form/multipart/registry/response/runtime proofs and narrow classification of infallible header parsing and streamed multipart unwrap-equivalent mutants.
 - **Proof:** the new xtask mutation command exits zero within its documented bound, covers each applicable package, emits no unexplained missed mutant, and a deliberate adjacent mutation makes it fail. `cargo run -p hemx-xtask -- test` remains green. req: test/020 req: test/021
 
 ## 3. Elect and enforce the release license policy

hemx-build/src/lib.rs

@@ -2326,6 +2326,93 @@ fn parse_error(path: &Path, err: impl std::fmt::Display) -> io::Error {
 mod tests {
     use super::*;
 
+    #[test]
+    fn public_heml_inspection_entry_points_preserve_paths_and_io_diagnostics() {
+        let root = std::env::temp_dir().join(format!(
+            "hemx-build-inspection-{}-{}",
+            std::process::id(),
+            std::thread::current().name().unwrap_or("test")
+        ));
+        std::fs::create_dir_all(&root).unwrap();
+        let template = root.join("card.heml");
+        let source = r#"<template h-for="todo in &self.todos"><button data-hemx-handle="save">Save</button></template>"#;
+        std::fs::write(&template, source).unwrap();
+
+        let from_source = diagnostics_for_heml_source(&template, source.to_owned()).unwrap();
+        let from_file = diagnostics_for_heml_file(&template).unwrap();
+        assert_eq!(from_file, from_source);
+        assert_eq!(from_source.len(), 1);
+        assert_eq!(from_source[0].file, template);
+        assert_eq!(from_source[0].directive, "data-hemx-handle");
+
+        let targets = generated_targets_for_heml_source(
+            &template,
+            r#"<main data-hemx-root="app"><section h-slot="notice"></section><button data-hemx-handle="save">Save</button></main>"#,
+        )
+        .unwrap();
+        assert_eq!(targets.len(), 1);
+        assert_eq!(targets[0].name, "save");
+        assert_eq!(
+            template_context_facts_for_heml_source(
+                &template,
+                "<main>{{ self.title }}</main>".to_owned(),
+            )
+            .unwrap(),
+            None
+        );
+        let crate_root = root.join("crate");
+        let templates = crate_root.join("templates");
+        std::fs::create_dir_all(crate_root.join("src")).unwrap();
+        std::fs::create_dir_all(&templates).unwrap();
+        std::fs::write(
+            crate_root.join("Cargo.toml"),
+            "[package]\nname='facts'\nversion='0.0.0'\n",
+        )
+        .unwrap();
+        std::fs::write(
+            crate_root.join("src/lib.rs"),
+            "#[derive(Hemplate)] struct Profile { title: String }\nstruct Plain { title: String }",
+        )
+        .unwrap();
+        let profile = templates.join("profile.heml");
+        let facts = template_context_facts_for_heml_source(
+            &profile,
+            "<main>{{ self.title }}</main>".to_owned(),
+        )
+        .unwrap()
+        .expect("Hemlate-derived context facts");
+        assert_eq!(facts.context_type, "Profile");
+        assert_eq!(facts.self_fields[0].name, "title");
+        std::fs::write(crate_root.join("src/broken.rs"), [0xff]).unwrap();
+        assert_eq!(
+            template_context_facts_for_heml_source(
+                &profile,
+                "<main>{{ self.title }}</main>".to_owned(),
+            )
+            .unwrap_err()
+            .kind(),
+            io::ErrorKind::InvalidData
+        );
+        std::fs::remove_file(crate_root.join("src/broken.rs")).unwrap();
+        assert_eq!(
+            template_context_facts_for_heml_source(
+                templates.join("plain.heml"),
+                "<main>{{ self.title }}</main>".to_owned(),
+            )
+            .unwrap(),
+            None
+        );
+        let missing = root.join("missing.heml");
+        for error in [
+            diagnostics_for_heml_file(&missing).unwrap_err(),
+            template_context_facts_for_heml_file(&missing).unwrap_err(),
+        ] {
+            assert_eq!(error.kind(), io::ErrorKind::NotFound);
+        }
+        let _ = std::fs::remove_dir_all(root);
+        // test req: diagnostics/004 req: diagnostics/006 req: surface/008
+    }
+
     #[test]
     fn generated_contract_fingerprint_and_client_bootstrap_are_deterministic() {
         let resource = |symbol: &str, component: &str, id| Resource {