Jnewhouse/write path

[jacksonrnewhouse]

This has my changes so far, namely

• Use async fn for SsfsBackend implementation. This is cleaner and requires less copying.
• Detect the uid and gid for the user, rather than hardcoded.
• First version of write support. Currently there is a race because the writes are pushed to remote in a separate thread, so you will have stale reads. This is the thing I'll fix next.

[mesa-dot-dev]

Mesa Description

This has my changes so far, namely

• Use async fn for SsfsBackend implementation. This is cleaner and requires less copying.
• Detect the uid and gid for the user, rather than hardcoded.
• First version of write support. Currently there is a race because the writes are pushed to remote in a separate thread, so you will have stale reads. This is the thing I'll fix next.

^{Description generated by Mesa. Update settings}

[mesa-dot-dev]

Performed full review of 670f0cc...125015d

Analysis

1. The design lacks a local transaction layer, causing every FUSE mutation to directly trigger asynchronous API calls without buffering or batching
2. No read-after-write consistency guarantees as file contents are always reconstructed from remote state rather than using local cache
3. Multi-block operations are inefficiently split into many independent commits with no ordering guarantees
4. Critical filesystem operations like fsync are implemented as no-ops, failing to provide expected durability semantics
5. Missing error propagation mechanism from the commit worker back to the FUSE layer, which could lead to silent failures

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^{0 files reviewed | 2 comments | Edit Agent Settings • Read Docs}

[mesa-dot-dev]

Because each write() call rebuilds the file from self.ssfs.read(ino) (lines 518‑548) and then enqueues the whole blob via backend.update_file (line 559), multi-chunk writes are effectively lossy. FUSE will typically send a large write as several 4 KiB chunks; after the first chunk we enqueue a commit but the remote repo still contains the old version when the next chunk arrives, so self.ssfs.read returns stale bytes and the new buffer only contains that one chunk. The final commit therefore only includes the last chunk that arrived before the worker caught up, corrupting any non-trivial write. We also never mutate the in-memory cache beyond update_file_size, so read-after-write sees the same stale data.

Please keep the dirty data local until all chunks for that file descriptor have been applied (e.g., track a per-inode buffer and update it directly), and only enqueue a commit once the file contents reflect the combined write. At minimum, stop re-fetching from the remote backend while commits are still outstanding.

 • 

Prompt for Agent

Task: Address review feedback left on GitHub.
Repository: mesa-dot-dev/git-fs#3
File: crates/git-fs/src/mesafuse.rs#L518
Action: Open this file location in your editor, inspect the highlighted code, and resolve the issue described below.

Feedback:
Because each `write()` call rebuilds the file from `self.ssfs.read(ino)` (lines 518‑548) and then enqueues the whole blob via `backend.update_file` (line 559), multi-chunk writes are effectively lossy. FUSE will typically send a large write as several 4 KiB chunks; after the first chunk we enqueue a commit but the remote repo still contains the *old* version when the next chunk arrives, so `self.ssfs.read` returns stale bytes and the new buffer only contains that one chunk. The final commit therefore only includes the last chunk that arrived before the worker caught up, corrupting any non-trivial write. We also never mutate the in-memory cache beyond `update_file_size`, so read-after-write sees the same stale data.

Please keep the dirty data local until all chunks for that file descriptor have been applied (e.g., track a per-inode buffer and update it directly), and only enqueue a commit once the file contents reflect the combined write. At minimum, stop re-fetching from the remote backend while commits are still outstanding.

[mesa-dot-dev]

This "workaround" replaces every empty file with a single '.' byte before base64 encoding (lines 65‑78 and 82‑95). That means any zero-length file we create or truncate is committed with one byte of content, so the file is no longer empty when it reaches Mesa/GitHub. Unless the server really does a special-case replacement on Lg==, this corrupts empty files.

If the Mesa API cannot accept an empty string today, we need a server-side fix or a different protocol knob (e.g., send content: Some(String::new()), or add an explicit flag) rather than mutating user data on the client.

 • 

Prompt for Agent

Task: Address review feedback left on GitHub.
Repository: mesa-dot-dev/git-fs#3
File: crates/git-fs/src/commit_worker.rs#L65
Action: Open this file location in your editor, inspect the highlighted code, and resolve the issue described below.

Feedback:
This "workaround" replaces every empty file with a single `'.'` byte before base64 encoding (lines 65‑78 and 82‑95). That means any zero-length file we create or truncate is committed with one byte of content, so the file is no longer empty when it reaches Mesa/GitHub. Unless the server really does a special-case replacement on `Lg==`, this corrupts empty files.

If the Mesa API cannot accept an empty string today, we need a server-side fix or a different protocol knob (e.g., send `content: Some(String::new())`, or add an explicit flag) rather than mutating user data on the client.