Fix invalidjson error for Wikitext: Get preview (and other commands)

[David-Gilman]

Summary

Wikitext: Get preview throws invalidjson: No valid JSON response for any non-trivial wikitext document since v4.0.3. This PR fixes it by removing the { method: 'GET' } override at all six call sites so mwbot's default POST is used.

Reproduction

1. Install the extension with default settings (wikitext.host = "en.wikipedia.org").
2. Open any moderately large .wikitext file (≥ ~8 KB).
3. Run Wikitext: Get preview (Shift+Cmd/Ctrl+V).
4. Error notification: invalidjson: No valid JSON response.

Root cause

mwbot.request(args, options) puts args into the POST form body. When options.method is overridden to 'GET', the underlying request library drops the form data — form is POST-only. The actual HTTP request becomes GET /w/api.php?format=json with no action parameter. MediaWiki responds with the API help page as HTML (Content-Type: text/html), mwbot then checks typeof body !== 'object' and throws invalidjson: No valid JSON response.

The { method: 'GET' } overrides were introduced in v4.0.3 (changelog: "Used explicit request methods to access the API to avoid some potential issues").

Why mwbot-patch.ts doesn't save the preview

src/mwbot-patch.ts correctly intercepts GET-method calls and moves params into qs. That works for small read-only queries — siteinfo, tokens, csrf, tag enumeration, readPage lookups. It cannot work for action=parse with a text parameter, because the request URL ends up containing the entire user document and exceeds the server's URI length limit.

Verified against en.wikipedia.org:

$ # 4 KB wikitext via GET
$ curl -s -o /dev/null -w "%{http_code} %{content_type}\n" \
    -G "https://en.wikipedia.org/w/api.php" \
    --data-urlencode "format=json" --data-urlencode "action=parse" \
    --data-urlencode "text@4kb.txt" --data-urlencode "contentmodel=wikitext"
200 application/json; charset=utf-8

$ # 8 KB wikitext via GET
$ curl -s -o /dev/null -w "%{http_code} %{content_type}\n" \
    -G "https://en.wikipedia.org/w/api.php" \
    --data-urlencode "format=json" --data-urlencode "action=parse" \
    --data-urlencode "text@8kb.txt" --data-urlencode "contentmodel=wikitext"
414 text/html; charset=iso-8859-1   # Request-URI Too Long

$ # 8 KB wikitext via POST
$ curl -s -o /dev/null -w "%{http_code} %{content_type}\n" \
    -X POST "https://en.wikipedia.org/w/api.php?format=json" \
    --data-urlencode "action=parse" --data-urlencode "text@8kb.txt" \
    --data-urlencode "contentmodel=wikitext"
200 application/json; charset=utf-8

The reproduction document I hit this with was 34 KB — far past the limit.

The fix

Drop the { method: 'GET' } overrides at all six call sites. mwbot's default POST works for every MediaWiki API action regardless of payload size, and is what mwbot's defaults (form: {}, qs: { format: 'json' }, json: true) are designed around.

Files touched:

• src/export_command/wikimedia_function/view.ts — showViewer (preview / page view). This is the one that surfaces as the user-visible bug.
• src/export_command/wikimedia_function/bot.ts — compareVersion (siteinfo).
• src/export_command/wikimedia_function/page.ts — postPage csrf/edit token fetches, pullPage, getValidTagList.

The two { method: 'POST' } call sites are untouched.

Possible follow-up (not in this PR)

With this change, no caller passes method: 'GET' to MWBot.prototype.request. That means src/mwbot-patch.ts becomes dead code and its two imports in extension-{node,web}.ts can be removed. I left that out to keep the diff minimal; happy to add it (or do a separate PR) if you'd prefer.

Test plan

• Verified by removing ,{method:"GET"} in the installed v4.0.4 bundle locally — preview works for a 34 KB document.
• Verified the API-layer change with curl against en.wikipedia.org (POST returns valid JSON for any size; GET 414s past ~8 KB).
• CI typecheck (signature is request(params: object, customRequestOptions?: RequestOptions) — second arg already optional).

Environment encountered on

• Extension: RoweWilsonFrederiskHolme.wikitext 4.0.4
• VSCode: 1.121.0
• OS: macOS (Darwin 25.4.0)
• Wiki host: en.wikipedia.org (default)

[Frederisk]

The purpose of introducing GET is to solve #125. I have indeed found that some sites will encounter exceptions when using POST. Perhaps in the worst case, we need to add a separate setting for this.