PR #69474: fix(gateway): restore webchat pure-image turn handling (#69358)

• Repository: openclaw/openclaw
• Author: Jaswir
• State: closed | merged: True
• Link: https://github.com/openclaw/openclaw/pull/69474

Description (problem / solution / changelog)

Summary

Fixes #69358 Fixes #69415 Fixes #69427

get-reply-run.ts now checks baseBodyForPrompt.trim() (which includes the inbound-context prefix) instead of baseBodyFinal.trim() for the empty-turn gate, and falls back to the plain "[User sent media without caption]" placeholder only when the entire prompt body is empty. This restores pure-image webchat turns that were bailing out with "I didn't receive any text in your message. Please resend or add a caption." (English) / "不可发送空消息" (localized same payload).

Root Cause

1. Webchat images arrive through replyOptions.images and — by explicit project design — do not stamp sessionCtx.MediaPath (see src/gateway/server-methods/chat.directive-tags.test.ts:1697-1698, which asserts ctx.MediaPath stays undefined on dispatch).
2. Commit eb10803691 ("fix(prompt): keep inbound chat ids out of system prefix") tightened the reply-run empty-turn gate from baseBodyForPrompt.trim() to baseBodyFinal.trim().length > 0 (i.e. the strict user body, prefix excluded).
3. The same commit also changed effectiveBaseBody so the "[User sent media without caption]" placeholder is always appended on top of inboundUserContext when there is no user body, instead of being used only as a last-resort fallback.
4. For a pure-image webchat turn: hasUserBody === false (no caption), hasMediaAttachment === false (no ctx.MediaPath) → the gate returns the empty-message payload and the image never reaches the vision model. When a caption is present, the placeholder text leaks into the Control UI user bubble on top of the Sender-metadata prefix.

All three issues are the same regression, reported from different angles:

• #69358 — pure-image Control UI send returns the empty-message error payload.
• #69415 — same behavior reported against the Web UI (localized message text).
• #69427 — screenshot/image upload broken after upgrading from 2026.4.5 → 2026.4.15 (the release that shipped eb10803691).

The Fix

Revert the three src/auto-reply/reply/get-reply-run.ts hunks introduced by eb10803691 back to the stable 2026.4.5 behavior:

• gate: baseBodyTrimmed = baseBodyForPrompt.trim() so the normal webchat inbound-context prefix keeps the run alive;
• effectiveBaseBody = baseBodyTrimmed ? baseBodyForPrompt : "[User sent media without caption]" so the placeholder is only used when there is truly nothing else, never appended on top of a non-empty prefix.

Also drops the media-only regression added by eb10803691 for the metadata-only-prefix bail-out — it encoded exactly the behavior this PR reverts.

Testing

This fix addresses the case where pure-image webchat (Control UI) sends were showing:

• agent reply "I didn't receive any text in your message. Please resend or add a caption." / "不可发送空消息" instead of a vision-model response;
• placeholder text [User sent media without caption] in the Control UI user bubble on top of the Sender-metadata prefix when a caption was supplied.

Verified locally:

• pnpm check:changed --staged — scoped typecheck + lint + guards + tests pass
• pnpm tsgo — core prod typecheck green
• pnpm test src/auto-reply/reply/get-reply-run.media-only.test.ts — 26/26 pass
• Manual repro in the Control UI (webchat): pure image + no caption → agent describes the image, user bubble renders the uploaded image.

Checklist

• Code changes are minimal and targeted (revert of three hunks in a single file + obsolete test removal)
• Fix addresses the root cause identified in #69358 / #69415 / #69427
• Commit message references the issue number

Changed files

• CHANGELOG.md (modified, +1/-0)
• src/auto-reply/reply/get-reply-run.media-only.test.ts (modified, +43/-0)
• src/auto-reply/reply/get-reply-run.ts (modified, +4/-6)