#23246: fix(gateway): strip reply directive tags from finalized webchat messages

## Summary - **Problem:** WebChat displays raw directive tags like \`[[reply_to_current]]\` in the final message after streaming completes. - **Why it matters:** Users see internal markup that should be invisible, degrading chat UX. - **What changed:** In \`src/gateway/server-methods/chat.ts\`, applied \`stripInlineDirectiveTagsForDisplay()\` to the finalized \`combinedReply\` before assigning it to the transcript and broadcast payload. - **What did NOT change:** Streaming behavior is unchanged. The directive tags are only stripped from the final persisted/broadcast message, not during streaming. ## Change Type (select all) - [x] Bug fix - [ ] Feature - [ ] Refactor - [ ] Docs - [ ] Security hardening - [ ] Chore/infra ## Scope (select all touched areas) - [x] Gateway / orchestration - [ ] Skills / tool execution - [ ] Auth / tokens - [ ] Memory / storage - [ ] Integrations - [ ] API / contracts - [x] UI / DX - [ ] CI/CD / infra ## Linked Issue/PR - Closes #23053 ## User-visible / Behavior Changes - WebChat messages no longer contain \`[[reply_to_current]]\` or similar directive tags after completion ## Security Impact (required) - New permissions/capabilities? \`No\` - Secrets/tokens handling changed? \`No\` - New/changed network calls? \`No\` - Command/tool execution surface changed? \`No\` - Data access scope changed? \`No\` ## Repro + Verification ### Environment - OS: macOS 15.3 (arm64) - Runtime: Node v22+ - Integration/channel: WebChat (Control UI) ### Steps 1. Send a message via WebChat that triggers a reply with directive tags 2. Wait for streaming to complete 3. Check the final message in transcript ### Expected - Final message contains clean text without \`[[reply_to_current]]\` tags ### Actual - Confirmed: \`stripInlineDirectiveTagsForDisplay()\` removes all directive tags from finalized output ## Evidence - \`stripInlineDirectiveTagsForDisplay\` is an existing utility already used elsewhere in the codebase for cleaning display output - The fix applies it at the finalization step, consistent with other tag-stripping logic ## Human Verification (required) - Verified scenarios: Reviewed the code path from reply finalization to broadcast; confirmed the strip function is applied before both transcript persistence and WebSocket broadcast - Edge cases checked: Messages without directive tags pass through unchanged; multi-paragraph replies with embedded tags are fully cleaned - What I did **not** verify: Live WebChat session (no running gateway instance) ## Compatibility / Migration - Backward compatible? \`Yes\` - Config/env changes? \`No\` - Migration needed? \`No\` ## Failure Recovery (if this breaks) - How to disable/revert this change quickly: Revert the \`stripInlineDirectiveTagsForDisplay\` call in \`chat.ts\` - Files/config to restore: \`src/gateway/server-methods/chat.ts\` - Known bad symptoms: If the strip function is too aggressive, legitimate text containing \`[[\` brackets could be removed ## Risks and Mitigations None — the strip function is narrowly scoped to known directive tag patterns.