[harminius]

Fixes MerginMaps/qgis-plugin#932

This adds an extended-path prefix to all Python filesystem operations on Windows so that it can work with files&folder > 260 characters.

Verified on Windows with OS long-path support off (default install), project path 317 chars: https://github.com/MerginMaps/python-api-client/actions/runs/39755718281

code	geodiff	client file handling	geodiff	push creates diff
master	2.3.1	fail	fail	fail
master	2.3.2	fail	pass	fail
this PR	2.3.1	pass	fail	fail (full upload)
this PR	2.3.2	pass	pass	pass

The \\?\ prefix is applied only at the filesystem call and never appears in the push payload. The geodiff half needs pygeodiff 2.3.2, which is bumped in a separate PR.

[harminius]

client-log.txt

[harminius]

db paths look fine

[coveralls]

Coverage Report for CI Build 39755347633

Coverage increased (+0.001%) to 84.046%

Details

• Coverage increased (+0.001%) from the base build.
• Patch coverage: 13 uncovered changes across 5 files (116 of 129 lines covered, 89.92%).
• 2 coverage regressions across 2 files.

Uncovered Changes

File	Changed	Covered	%
mergin/utils.py	19	12	63.16%
mergin/client.py	11	9	81.82%
mergin/client_pull.py	18	16	88.89%
mergin/fs.py	26	25	96.15%
mergin/merginproject.py	45	44	97.78%
Total (7 files)	129	116	89.92%

Coverage Regressions

2 previously-covered lines in 2 files lost coverage.

File	Lines Losing Coverage	Coverage
mergin/client_pull.py	1	83.27%
mergin/client.py	1	88.75%

---

Coverage Stats

Relevant Lines:	6030
Covered Lines:	5068
Line Coverage:	84.05%
Coverage Strength:	0.84 hits per line

---

💛 - Coveralls

[harminius]

Let's try to use \\?\-prefixed paths for geodiff calls and other (all) file I/O.

[harminius]

PR history:

Debugging info:
Pull works as py-client saves the diffs to tmp dir
However, there is always a check if there's something to push after the pull.

Push treats every gpkg with editing mode enabled as well as with original vs. current gpkg checksum mismatch (which is quite common) as potentially updated, and we rely on geodiff to calculate the real changes. Geodiff creates an empty diff file even when there is no change.
Geodiff's create_changeset() fails because it's not possible to create a file due to the Windows path length limit. It then pushes the whole file. Then we want to apply the push changes to the basefile. So geodiff removes the original geopackage and copies the current copy, which apparently changes the checksum, and we're caught in the loop. ➿

Site	Feature
merginproject.py get_push_changes	push
merginproject.py get_local_delta	pull, local changes detection
client_pull.py get_download_diff_files	pull, v1 fallback
client_pull.py pull_project_async v2 loop	pull, v2
client_pull.py download_diffs_async	get_file_diff / version viewer / reports

This is a minimal fix for the issue. There are other enhancements/issue mitigations:

1. Shorten diff name
   Store diff files locally under a short, flat name, decoupled from the file's path in the project — e.g. .mergin/diffs/ instead of .mergin/-diff-. Fixes works esp. for files nested deep in the subfolders. This does not require server changes - the server doesn't care what we call the local file.

Path	Length
Live file <rel>	P + R + 1
Basefile .mergin<rel> — already mandatory today	P + R + 9
Diff today .mergin<rel>-diff-	P + R + 51
Diff flattened .mergin\diffs<uuid>	P + 51 (constant)
Same, 16-char id	P + 31 (constant)

2. Safeguard for any infinite sync loop
   sync_project_generator's while has_changes has no iteration limit. Track, per file, how many consecutive iterations it was pushed as a full upload with no diff; if the same versioned file does this N times in a row (e.g. 2–3), raise a ClientError naming the file instead of continuing. This is cause-agnostic - it also protects against any other future reason a changeset can't be computed.

3. Long path error workaround
   Use \\?\-prefixed paths for geodiff calls and other file I/O.

4. Use a temp folder for push diffs, as it is used for pull diffs already.