fix(bundle): use POSIX separators in manifest paths and tar arcnames

[galuis116]

Problem

On Windows, vouch export writes bundle paths into manifest.json
using the native \ separator while tarfile records member
names with /. Every bundle vouch produces on Windows is therefore
self-invalid:

• manifest.counts is {claims: 0, pages: 0, sources: 0, ...} for
  every KB regardless of content (the per-subdir counter at
  src/vouch/bundle.py:90 uses
  f["path"].startswith(f"{sub}/"), which never matches
  sources\...).
• vouch export-check on the bundle vouch just produced returns
  ok: false with file in bundle but not in manifest for every
  tar member and manifest lists missing file for every manifest
  entry.
• vouch import-apply is a silent no-op for the same reason: the
  manifest-paths set lookup at src/vouch/bundle.py:264 is keyed
  on the \-flavoured strings, so every tar member is treated
  as "not in manifest" and skipped.

Portable bundles are a load-bearing feature (README: "Portable
bundles"), so this corrupts the only mechanism for moving a KB
between repos on any Windows host. The bug is invisible to CI
because .github/workflows/ci.yml only runs on ubuntu-latest,
where Path already produces POSIX separators.

Fix

Normalise paths to POSIX in two places in src/vouch/bundle.py:

@@ build_manifest
     for rel, abs_path in _iter_export_files(kb_dir):
         data = abs_path.read_bytes()
         files.append({
-            "path": str(rel),
+            "path": rel.as_posix(),
             "size": len(data),
             "sha256": sha256_hex(data),
         })

@@ export
     with tarfile.open(dest, "w:gz") as tar:
         for rel, abs_path in _iter_export_files(kb_dir):
-            tar.add(abs_path, arcname=str(rel))
+            tar.add(abs_path, arcname=rel.as_posix())

POSIX separators are the on-the-wire format anyway: tarfile uses
/, _unsafe_name_reason already checks startswith("/"), and
the startswith(f"{sub}/") counter at line 90 assumes the same.
Existing Linux/macOS bundles are byte-identical after this change;
Windows bundles become valid. No on-disk-layout, schema, or
bundle-format change — the spec stays as Linux already
emitted it.

Tests

Added tests/test_bundle.py::test_manifest_paths_match_tar_member_names
as a regression contract: asserts no backslash in any manifest
path, asserts the manifest path set equals the tar member set, and
asserts manifest["counts"] is non-zero for claims, pages,
and sources. This guards against str(rel) slipping back in.

Local run on Windows (Python 3.12.13):

• ruff check src tests — passes.
• pytest tests/test_bundle.py — 6/7 pass (the new contract
  test is among them; test_export_import_round_trip now reaches
  a separate, pre-existing Windows bug in put_page CRLF
  handling that is masked on Linux — out of scope for this PR,
  reportable separately).
• End-to-end CLI: vouch init → vouch source add →
  vouch export → vouch export-check now returns
  {"ok": true, "issues": []} and manifest.counts.sources is
  2 (was 0).

On Linux/macOS, behaviour and bundle bytes are unchanged.

Fixes #72

Summary by CodeRabbit

• Bug Fixes
  • Fixed Windows bundle export path format inconsistency that made exported bundles incompatible with validation and import operations. Bundles now export consistently across all platforms. Previously exported Windows bundles should be re-exported.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between c3accb6 and e1917a5.

📒 Files selected for processing (3)

• CHANGELOG.md
• src/vouch/bundle.py
• tests/test_bundle.py

---

📝 Walkthrough

Walkthrough

This PR fixes a critical Windows bug where vouch export produced self-invalid bundles due to path separator mismatch: manifest.json recorded paths with \ while tar members used /. The fix normalizes all paths to POSIX separators, and includes a regression test and changelog documentation.

Changes

Cross-platform bundle path normalization

Layer / File(s)

Summary

Path normalization in bundle export and import src/vouch/bundle.py, tests/test_bundle.py, CHANGELOG.md

build_manifest and export now normalize file paths to POSIX / separators via Path.as_posix() instead of platform-dependent str(rel). New regression test test_manifest_paths_match_tar_member_names validates that manifest paths contain no backslashes and tar member names exactly match manifest path values. Changelog documents the fix, impact on prior Windows bundles, and unchanged behavior for Linux/macOS bundles.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Possibly related issues

• \#72: Direct fix implementation for the reported Windows bundle export bug where manifest paths used backslash separators while tar members used forward slashes, breaking export-check and import-apply workflows.

Poem

🐰 A rabbit hops through paths of old,
Found Windows breaks what Linux holds,
Slashes forward, forward still,
Now bundles work on every hill!
POSIX peace across the land! 🌍

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly and specifically describes the main changes: normalizing POSIX separators in manifest paths and tar member arcnames to fix the Windows bundle export bug.
Linked Issues check	✅ Passed	The PR fully addresses all coding requirements from issue #72: path normalization to POSIX in manifest and tar arcnames, comprehensive test coverage validating path consistency, and preservation of existing bundle compatibility.
Out of Scope Changes check	✅ Passed	All changes are directly aligned with issue #72 requirements: bundle.py fixes, CHANGELOG documentation, and new regression test. No unrelated modifications detected.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

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