compress parsed data to .json.zst

AGENTS.md

@@ -51,7 +51,7 @@ POST /uploadSave  ->  store blob, status "uploaded"  ->  SaveParsingOperation
                                                           (background: parsing,
                                                            saving_results, done)
 GET  /getSaveStatus  (polled by the frontend until status is "done" or "error")
-GET  /getSaveData    (filtered parse result as JSON)
+GET  /getSaveData    (filtered parse result as zstd-compressed JSON)
 GET  /getSaveFile    (the uploaded blob, unchanged)
 ```
 
@@ -79,11 +79,13 @@ archived save    ->  tar { "meta", "gamestate", ... }  -> zstd -> upload
   [SaveArchive.cs](ParadoxSaveParser.WebAPI/SaveArchive.cs), which streams
   through `DecompressionStream` and `TarReader`. The whole archive is never
   loaded into memory.
-- Upload limits come from the `SaveUpload` config section.
-  `MaxSizeCompressedBytes` is checked against `Content-Length` and then again
-  while the body is copied, because chunked requests have no length.
-  `MaxSizePlainTextBytes` is checked against the tar entry size once the upload
-  has finished. Every rejected upload deletes its database row and file.
+- Upload limits come from the `SaveUpload` config section, in MiB
+  (`MaxSizeCompressedMegabytes`, `MaxSizePlainTextMegabytes`). The code uses
+  their byte equivalents, the `…Bytes` properties, which are not saved to the
+  config. The compressed limit is checked against `Content-Length` and then
+  again while the body is copied, because chunked requests have no length. The
+  plain text limit is checked against the tar entry size once the upload has
+  finished. Every rejected upload deletes its database row and file.
 
 ### Runtime files
 
@@ -101,8 +103,11 @@ lands in the project folders.
 - **Nothing is deployed and there is no data worth keeping.** Do not write
   database migrations or backward compatibility code for old layouts; change
   the schema directly.
-- Open items are in [TODO.md](TODO.md): compressing parsed results,
-  re-parsing when the query changes, automatic database cleanup.
+- Open items are in [TODO.md](TODO.md): re-parsing when the query changes,
+  automatic database cleanup.
+- Parsed results are stored as `<id>.parsed.json.zstd` and `/getSaveData`
+  serves that file unchanged as `application/zstd`. The client decompresses
+  it; the server never does.
 - The WebAPI exits with code 1 after Ctrl+C even though it logs "server
   stopped". This has not been investigated yet.
 
@@ -152,17 +157,20 @@ A one-off C# check can be a .NET 10 file-based app in `TEMP/`
 
 ### Checking your work
 
-**Always build the solution and run the tests after changing code.** Do not
-report a change as finished until both pass.
+**Always build the solution after changing code.** `dotnet build
+ParadoxSaveParser.sln` must finish with zero errors and no **new** warnings.
+Three warnings are known and come from sqlite-net-pcl's
+`SQLitePCLRaw.lib.e_sqlite3` dependency (NU1903 twice, NETSDK1206 once).
+Everything else is yours.
+
+**Never run tests or benchmarks unless the user asks for it.** This is a
+strict ban. It covers `dotnet test`, the benchmarks, and starting the WebAPI
+to exercise routes with `curl`. When a change needs checking that way, say
+what should be run and wait for the user to ask. When they do:
 
-- `dotnet build ParadoxSaveParser.sln` must finish with zero errors and no
-  **new** warnings. Three warnings are known and come from
-  sqlite-net-pcl's `SQLitePCLRaw.lib.e_sqlite3` dependency (NU1903 twice,
-  NETSDK1206 once). Everything else is yours.
 - `dotnet test ParadoxSaveParser.Lib.Tests` must pass completely.
-- A WebAPI change is not verified until it has been run: start the server
-  from `TEMP/` and exercise the route with `curl`, including the error cases.
-  Stop the server afterwards.
+- For a WebAPI check, start the server from `TEMP/`, exercise the route with
+  `curl` including the error cases, then stop the server.
 - For a parser performance change, run the relevant benchmark before and
   after, and report both numbers.