feat(gemini): thinking as Open WebUI's native, localized reasoning block (1.19.0)

[owndev]

Why

Since 1.18.0, Gemini's thinking looked different depending on the chat:

• Tool rounds: shown as Open WebUI's own reasoning item, localized ("Gedanke für 5 Sekunden").
• Normal answers: the pipe wrote its own English block <details><summary>Thought (5s)</summary> and showed the English status Thinking… <preview>. The duration also counted the answer time.

#160 (@swarnat) proposed instance-wide valves for translating those texts. It was closed in favour of this change: Open WebUI's frontend already renders and localizes <details type="reasoning"> blocks per user, so no valve is needed. Thanks to @swarnat for raising it.

Change (Google Gemini pipeline 1.18.0 → 1.19.0)

• Native reasoning block. _thinking_details_block writes <details type="reasoning" done="true" duration="N">. Open WebUI shows "Thought for N seconds" in the user's language ("Nachgedacht für N Sekunden").
  • <summary>Thought (Ns)</summary> stays for API clients and other renderers.
  • The [Bug]: Previous thinking summary gets sent in later conversations #176 history cleanup (_THINKING_DETAILS_RE) is unchanged. It still strips the plain blocks of older chats, the new blocks, and a stopped done="false" block.
• Live while thinking. In streamed chat answers the pipe shows a done="false" block: Open WebUI's "Thinking..." with a spinner, plus the thoughts so far when expanded.
  • It is sent through replace events when new thoughts arrive, at most every 0.4 s.
  • On the first answer part, one replace switches the block to done="true". The answer then continues as chat:message:delta.
  • The English Thinking… <preview> status is gone.
  • If round one ends with tool calls, the live block is cleared before Open WebUI's reasoning item takes over.
• Duration is measured from the first thought to the first answer part. Before, it ran to the end of the stream. Non-streaming answers keep the request duration.
• Search statuses. Google Search grounding now emits Open WebUI's own localized statuses:
  • web_search_queries_generated: "Suche..." with the query chips; each query is sent once, because Open WebUI's keyed list throws on duplicates.
  • web_search: "N Seiten durchsucht", with items and no urls, as Open WebUI's backend does.
• Unchanged:
  • tool rounds and live rounds of the tool loop (reasoning_content / reasoning_details);
  • background tasks (no thinking block);
  • the image, video and error texts;
  • all valves;
  • the API path, apart from the block shape and the duration.
• Docs: "Thinking Summaries in Conversation History", the Web search section and the README bullet.

Verification

Run	Result
All suites, v0.11.4-slim, --strict-known (merged with main 2fc7bcc)	547 PASS, 0 FAIL, 0 KNOWN, no obsolete marker (1151 s)
gemini, v0.11.3-slim, --strict-known	165 PASS, 0 FAIL, 0 KNOWN
Meta-test (E2E_MOCK_FAULT=500)	57 PASS, 386 FAIL, 0 KNOWN
Smoke runner --dry-run-mock	15 PASS, 0 FAIL, 2 SKIP; the key in no output file
check_owui_api.sh, ruff 0.11.10 check + format	clean
Pipeline without the query deduplication (--file)	gemini.grounding.status FAIL (queries sent twice)

• Mutation round: 15 mutants of the new behaviour, all killed. They cover:

  • the block attributes, the done flag and the throttle;
  • the switch, the duration end and the regex;
  • urls/items and the statuses;
  • the tool-round cleanup.

• Against 1.18.0: 12 of the 32 checks in the affected groups fail.

• Independent review: no blocking finding. The duplicate-query and docs findings are fixed in be4dab5.

• Verified against the Open WebUI v0.11.4 sources:

  • the frontend parser (utils/marked/extension.ts) and Collapsible.svelte;
  • StatusItem.svelte and the de-DE translations;
  • the backend middleware status shapes;
  • which socket events are persisted.

  Collapsible.svelte of v0.9.0 has the same reasoning block, so required_open_webui_version stays 0.9.0.

Not verified yet

A real browser with a German UI and the real Gemini API (the maintainer tests before merge):

1. gemini-2.5-flash streamed:

   • "Denke nach..." with a spinner while thinking, then "Nachgedacht für N Sekunden", where N is the thinking time only;
   • no English "Thinking…" status.

2. Non-streaming (GOOGLE_STREAMING_ENABLED=false): the finished block only.

3. A grounded answer:

   • "Suche..." with the queries, then "N Seiten durchsucht" with the list;
   • [n] citations and sources still there.

   Every site shows the same favicon, because Gemini's links are Google redirect URLs.

4. Stop while thinking: "Gedanke" without a spinner; the next message works.

5. An image model: the localized block above the image.

Supersedes #160.

🤖 Generated with Claude Code