[Push] Add a local files-diff command

[adamziel]

reprint files-diff <target-url> --state-dir=DIR --fs-root=DIR prints the pair's local minimized push operation plan before target exclusions by comparing the local tree with its previous local index. It makes no network request and requires no secret.

Background

A completed files-push saves the local path type, size, and ctime used to plan the next push. Until now that comparison was only available inside files-push.

This change

files-diff derives the same pair key as files-push and requires the same target URL, state directory, and local tree that produced the previous local index. It emits JSONL push records with path_b64, type, size, and ctime, followed by delete records with path_b64 and a complete record with both counts. Paths remain base64 so arbitrary filesystem bytes survive JSON.

After adding wp-content/themes/my-theme/style.css and deleting wp-content/plugins/old-plugin, a report looks like this:

$ reprint files-diff 'https://example.com/export.php?site-export-api' --state-dir=.reprint --fs-root=public
{"command":"files-diff","action":"push","path_b64":"d3AtY29udGVudC90aGVtZXMvbXktdGhlbWUvc3R5bGUuY3Nz","type":"file","size":8421,"ctime":1784822400}
{"command":"files-diff","action":"delete","path_b64":"d3AtY29udGVudC9wbHVnaW5zL29sZC1wbHVnaW4="}
{"command":"files-diff","status":"complete","local_paths_to_push":1,"local_paths_to_delete":1}

The command leaves the previous local index unchanged and stores no resume state. An interrupted run discards its temporary plan; the next run rebuilds and prints the complete report from the beginning.

This renames local_index_at_previous_push.jsonl to previous_local_index.jsonl and gives PushPlan a caller-supplied previous local index, so files-push and files-diff use the same local diff implementation.

Testing

Complete a files-push, stop the target, then add, edit, delete, and change the type of paths in the same local tree. Run files-diff with the same target URL, state directory, and local tree; check the base64 JSONL push and delete records and final counts. Run it again without changing the tree and confirm it prints the same complete report without changing previous_local_index.jsonl.

[github-actions]

Pull pipeline performance — large-directory

Site: large-directory · 2,000+ plus targeted file-transfer scenarios files · 10,000 posts · 25,000 postmeta · PHP 8.5.8

Stage	PR	trunk	Δ	Status	Details
playground-sqlite-db-pull	9.91 s	9.63 s	⚪ +281 ms (+2.9%)	✓	condition=db-pull in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=lexer native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=selected trunk: condition=db-pull in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=lexer native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=selected
playground-sqlite-db-apply	3.62 s	3.65 s	⚪ -30 ms (-0.8%)	✓	condition=db-apply to SQLite in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=parser native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=verified native_ast=WP_MySQL_Native_Parser_Node sqlite_driver_parser=verified trunk: condition=db-apply to SQLite in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=parser native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=verified native_ast=WP_MySQL_Native_Parser_Node sqlite_driver_parser=verified
Total	13.53 s	13.28 s	⚪ +251 ms (+1.9%)

_{Numbers carry runner noise; treat single-run deltas as directional, not authoritative.}

_{📈 Trunk performance history — commit-by-commit timeline.}