fix(linker): accept plain unified patches

[jdx]

Summary

• accept plain unified diffs that omit diff --git headers
• derive safe target paths from --- / +++ headers while preserving git-style parsing
• support multi-file patches, additions, and deletions
• retain traversal and symlink protections for header-derived paths

Root cause

The patch splitter only populated each section's target path from a diff --git line. Plain diff -u patches were parsed into a body with no path and failed with patch section missing file path, even though pnpm accepts them.

Reported in Discussion #1018.

Validation

• cargo fmt --check
• cargo test -p aube-linker patches::tests
• cargo clippy -p aube-linker --all-targets -- -D warnings
• reporter's end-to-end reproduction against the debug aube binary

---

Note

Medium Risk
Changes patch parsing and file-boundary logic on the install/link path; mistakes could mis-apply patches or split files wrong, though existing path-escape and symlink guards still apply.

Overview
Fixes patch application when users supply plain diff -u output (no diff --git lines), which previously failed because each section never got a target path.

split_patch_sections now splits on either git boundaries or unified-diff file headers: paths come from --- / +++ via unified_header_path (including bare paths and timestamp suffixes), and hunk line counts distinguish the next file’s --- from hunk content— including multi-hunk and multi-file plain patches, adds (--- /dev/null), and deletes (+++ /dev/null). Git-style parsing is unchanged. Empty-parse errors now say “no parseable file sections.”

Adds tests for plain unified apply paths, traversal rejection, and zero-count hunks at file boundaries.

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Review details

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📥 Commits

Reviewing files that changed from the base of the PR and between 06601ee and f7bfe8b.

📒 Files selected for processing (1)

• crates/aube-linker/src/patches.rs

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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^{Reviewed by Cursor Bugbot for commit 9581220. Configure here.}

[greptile-apps]

Greptile Summary

This PR teaches split_patch_sections to recognise plain diff -u patches (no diff --git header) in addition to git-style ones. It does so by tracking per-hunk line counts so that a --- prefix can be correctly identified as a new file boundary rather than a deletion hunk line after the previous hunk's counter reaches zero.

• Two new helpers are introduced: unified_header_path strips a//b/ prefixes and tab-separated timestamps to derive a safe relative path, and hunk_line_counts parses @@ -<n>[,<c>] +<n>[,<c>] @@ headers into (old_count, new_count) tuples.
• The existing diff --git code path is fully preserved; hunk_remaining is reset whenever a diff --git line is seen, so git-style parsing is unchanged.
• Six new tests cover single-file, multi-hunk, multi-file, add/delete, zero-count-hunk, and path-escape cases; all traversal and symlink protections are exercised by the existing guards in apply_multi_file_patch.

Confidence Score: 5/5

Safe to merge — the plain-patch path shares all existing traversal and symlink guards, git-style parsing is unchanged, and the new hunk-count boundary detection is well-tested.

The hunk-counter logic correctly distinguishes --- file headers from deletion hunk lines by tracking remaining old/new line counts per hunk. Zero-count hunks immediately clear the counter so the following --- is correctly treated as a boundary. Path derivation falls back to bare paths after stripping prefixes and timestamps. All security-sensitive operations are reached identically for both git-style and plain patches.

No files require special attention.

Important Files Changed

Filename	Overview
crates/aube-linker/src/patches.rs	Adds hunk-count tracking and two helper functions to accept plain unified diffs alongside git-style patches; git-style path and all security guards (path traversal, symlink) are unchanged

_{Reviews (2): Last reviewed commit: "fix(linker): handle unified patch edge c..." | Re-trigger Greptile}