fix(source-fs): apply size limit only to code files; PDF/image/markdown bypass walker cap (Bug #2)

v0.20.0 sub-item 1 dogfood report 의 Bug #2 — `[ingest.code].max_file_bytes`
가 walker 단계의 모든 file 에 일률 적용 → PDF/image/markdown 의 대부분 (256 KB+)
이 walker pre-extract skip. fix:

- `crates/kebab-source-fs/src/code_meta.rs`: `pub(crate) fn is_code_file(path)
  -> bool` helper 추가 (= `code_lang_for_path(path).is_some()`).
- `crates/kebab-source-fs/src/connector.rs:168-190`: walker size-cap check 가
  `is_code_file(&abs_path) && is_oversized(...)` short-circuit. PDF/image/
  markdown 는 walker bypass — parser 의 자체 size control (lopdf load_mem,
  image OCR max_pixels) 가 cover.
- `crates/kebab-source-fs/src/connector.rs` 기존 mod tests 안 추가:
  `size_cap_skips_only_code_files` — 300 KB PDF + MD + .rs 의 walker 결과
  검증. 기존 sibling test (huge.rs / longfile.rs, fixture 명 `.rs`) regression 0.

spec:  docs/superpowers/specs/2026-05-27-v0.20-sub1-bugfix-spec.md (§3)
plan:  docs/superpowers/plans/2026-05-27-v0.20-sub1-bugfix-plan.md (Step 1)
prior: b4d9e60 (PR #189)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/kebab-source-fs/src/code_meta.rs

@@ -109,6 +109,15 @@ pub(crate) fn is_generated_file(path: &Path) -> Result<bool> {
     )
 }
 
+/// Returns true when `path`'s filename/extension is recognised as a code
+/// file (per `code_lang_for_path`). Used by the walker to apply
+/// `[ingest.code].max_file_bytes` / `max_file_lines` only to code files,
+/// not to PDF/image/markdown (which have their own size controls in
+/// their respective parsers).
+pub(crate) fn is_code_file(path: &Path) -> bool {
+    code_lang_for_path(path).is_some()
+}
+
 /// Check if `path` exceeds `max_bytes` or `max_lines`. Byte cap first
 /// (cheap), then line cap (streaming with early exit).
 pub(crate) fn is_oversized(path: &Path, max_bytes: u64, max_lines: u32) -> Result<bool> {

crates/kebab-source-fs/src/connector.rs

@@ -165,13 +165,16 @@ impl FsSourceConnector {
                 continue;
             }
 
-            // Size-cap check (byte or line limit).
-            if crate::code_meta::is_oversized(
-                &abs_path,
-                self.max_file_bytes,
-                self.max_file_lines,
-            )
-            .unwrap_or(false)
+            // v0.20.0 sub-item 1 bugfix (#2): size-cap applies ONLY to
+            // code files. PDF/image/markdown bypass — their parsers
+            // have their own size controls. spec §3.3.
+            if crate::code_meta::is_code_file(&abs_path)
+                && crate::code_meta::is_oversized(
+                    &abs_path,
+                    self.max_file_bytes,
+                    self.max_file_lines,
+                )
+                .unwrap_or(false)
             {
                 fs_skips.skipped_size_exceeded =
                     fs_skips.skipped_size_exceeded.saturating_add(1);
@@ -184,7 +187,7 @@ impl FsSourceConnector {
                     path = %rel_path.display(),
                     max_bytes = self.max_file_bytes,
                     max_lines = self.max_file_lines,
-                    "skip: file exceeds size cap"
+                    "skip: code file exceeds size cap"
                 );
                 continue;
             }
@@ -764,4 +767,28 @@ mod tests {
             skips.skipped_size_exceeded
         );
     }
+
+    #[test]
+    fn size_cap_skips_only_code_files() {
+        use tempfile::tempdir;
+        let tmp = tempdir().unwrap();
+        let root = tmp.path().to_path_buf();
+
+        // 300 KB pdf / md / rs (each > 262 144 byte cap)
+        std::fs::write(root.join("paper.pdf"), vec![b'%'; 300_000]).unwrap();
+        std::fs::write(root.join("notes.md"), vec![b'#'; 300_000]).unwrap();
+        std::fs::write(root.join("big.rs"), vec![b'/'; 300_000]).unwrap();
+
+        let cfg = cfg_with_size_cap(root.to_str().unwrap(), 262_144, 5_000);
+        let connector = FsSourceConnector::new(&cfg).unwrap();
+        let (assets, skips) = connector.scan_with_skips(&SourceScope::default()).unwrap();
+
+        let paths: Vec<_> = assets.iter().map(|a| a.workspace_path.0.as_str()).collect();
+        assert!(paths.iter().any(|p| p.contains("paper.pdf")), "PDF must pass: {paths:?}");
+        assert!(paths.iter().any(|p| p.contains("notes.md")), "MD must pass: {paths:?}");
+        assert!(!paths.iter().any(|p| p.contains("big.rs")), "code file must skip: {paths:?}");
+
+        assert_eq!(skips.skip_examples.size_exceeded.len(), 1);
+        assert!(skips.skip_examples.size_exceeded[0].contains("big.rs"));
+    }
 }