diff --git a/.ai/DECISIONS.md b/.ai/DECISIONS.md
index 2f8b7153..0e06d4dc 100644
--- a/.ai/DECISIONS.md
+++ b/.ai/DECISIONS.md
@@ -13,6 +13,25 @@
 
 ---
 
+## 2026-04-30 — Allow `escalated_to_id` to send chat messages in claimed sessions
+
+**Context:** During browser QA, clicking "Get AI analysis" on the magic-moment screen returned `POST /ai-sessions/{id}/chat → 400`. The senior tech who claimed the session is stored as `escalated_to_id` on `AISession`, not `user_id` (which remains the junior who created the session). `unified_chat_service.send_chat_message` queried `WHERE ai_sessions.user_id = :user_id`, so the senior's ID never matched and the endpoint rejected the request.
+
+**Decision:** Extend the ownership check in `send_chat_message` to `OR ai_sessions.escalated_to_id = :user_id` using SQLAlchemy `or_()`. This is the minimal, correct fix: the session model already has a semantically valid "also owns" field for the claiming senior; extending the WHERE clause makes that ownership real.
+
+**Rejected:**
+
+- **Transfer `user_id` to the senior on claim.** Breaks the audit trail — `user_id` is the originating engineer throughout the session lifecycle. Any query scoped to "sessions this engineer worked on" would silently lose the junior's history.
+- **A separate `can_send_message` service method.** Adds indirection with no benefit for v1. One `or_()` line in the existing query is sufficient.
+- **Checking a role/permission flag instead.** Role gating (engineer/admin) already happens at the claim endpoint. The chat-send check is about session ownership, not role. Mixing the two concerns would be confusing.
+
+**Consequences:**
+- Seniors can send AI briefings and continue chat work in sessions they have claimed. Core escalation pickup flow unblocked.
+- Any future caller of `send_chat_message` should be aware that "user_id or escalated_to_id" is the ownership rule. The service-level check is the single enforcement point.
+- `user_id` remains the originating engineer for all audit, history, and analytics queries. No data migration needed.
+
+---
+
 ## 2026-04-29 — Consolidate the three per-escalation AI calls into one structured generation
 
 **Context:** A single user-initiated escalation currently triggers three separate Sonnet calls, all summarizing the same source material (session state, steps taken, "what we know") from slightly different angles:
diff --git a/.ai/SESSION_LOG.md b/.ai/SESSION_LOG.md
index 3698a010..8945a0cd 100644
--- a/.ai/SESSION_LOG.md
+++ b/.ai/SESSION_LOG.md
@@ -12,6 +12,26 @@
 
 ---
 
+## 2026-04-30 — Claude Code — Browser QA pass complete; chat ownership bug found and fixed; PR #155 ready
+
+- Ran full browser QA pass on the escalation mode feature using gstack `/qa` skill.
+- **Critical bug found and fixed (commit `dc69c9d`):** `POST /ai-sessions/{id}/chat → 400` when senior clicked "Get AI analysis" on the magic-moment screen. Root cause: `unified_chat_service.send_chat_message` checked `AISession.user_id == user_id` only; senior is stored as `escalated_to_id`, not `user_id`. Fix: `or_(AISession.user_id == user_id, AISession.escalated_to_id == user_id)` in the WHERE clause.
+- **All 7 QA scenarios passed:**
+  - Post-escalation redirect: junior routed to `/` with "Session escalated" toast.
+  - Magic-moment screen: header, metadata, two-column AI assessment, 2-option CTA rendered correctly.
+  - "I'll take it from here": claim → dismiss overlay → composer focused.
+  - "Get AI analysis": claim → briefing sent → AI responded → task lane populated (after `dc69c9d` fix).
+  - Task lane copy button: toast + checkmark visual feedback.
+  - Chip expansion: inline detail card + "Open in Tasks panel" scroll.
+  - Post-claim toolbar re-open: dismissible mode with Close-only CTA.
+- **Known non-blockers:** "Continue where X left off" path untestable on first pickup (`hasTaskLane=false` is correct v1 behavior). 409 race condition untestable with one senior account; backend logic code-reviewed and correct.
+- Backend tests: 17/17 pass.
+- Updated `HANDOFF.md` to reflect QA complete; updated `CURRENT_TASK.md` status to engineering+QA complete; appended architectural decision to `DECISIONS.md`.
+- Branch `feat/escalation-metric-endpoint` is ready for PR #155 to be marked ready-for-review.
+- **Files touched this session:** `backend/app/services/unified_chat_service.py`, `.ai/HANDOFF.md`, `.ai/CURRENT_TASK.md`, `.ai/DECISIONS.md`, `.ai/SESSION_LOG.md`.
+
+---
+
 ## 2026-04-29 04:30 EDT — Claude Code — Live QA bash, pickup bug fixes, AI summary consolidation surfaced
 
 - User on a freshly swapped computer ran the live QA flow. Identified two bugs missed by static analysis from the previous session: