diff --git a/AGENTS.md b/AGENTS.md
index 31d0868..053c4ed 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -218,11 +218,12 @@ issues labeled `action` that have no active tmux session, then spawns
 **Session lifecycle**:
 1. `action-poll.sh` finds open `action` issues with no active tmux session.
 2. Spawns `action-agent.sh <issue_num>`.
-3. Agent creates tmux session `action-{issue_num}`, injects prompt (formula + prior comments).
-4. Claude executes formula steps using Bash and other tools, posts progress as issue comments.
-5. For human input: Claude sends a Matrix message and waits; the reply is injected into the session by `matrix_listener.sh`.
-6. When complete: Claude closes the issue with a summary comment. Session exits.
-7. Poll detects no active session on next run — nothing further to do.
+3. Agent creates Matrix thread, exports `MATRIX_THREAD_ID` so Claude's output streams to the thread via a Stop hook (`on-stop-matrix.sh`).
+4. Agent creates tmux session `action-{issue_num}`, injects prompt (formula + prior comments).
+5. Claude executes formula steps using Bash and other tools, posts progress as issue comments. Each Claude turn is streamed to the Matrix thread for real-time human visibility.
+6. For human input: Claude sends a Matrix message and waits; the reply is injected into the session by `matrix_listener.sh`.
+7. When complete: Claude closes the issue with a summary comment. Session exits.
+8. Poll detects no active session on next run — nothing further to do.
 
 **Environment variables consumed**:
 - `CODEBERG_TOKEN`, `CODEBERG_REPO`, `CODEBERG_API`, `PROJECT_NAME`, `CODEBERG_WEB`
@@ -266,7 +267,7 @@ sourced as needed.
 | `lib/load-project.sh` | Parses a `projects/*.toml` file into env vars (`PROJECT_NAME`, `CODEBERG_REPO`, `WOODPECKER_REPO_ID`, monitoring toggles, Matrix config, etc.). | env.sh (when `PROJECT_TOML` is set), supervisor-poll (per-project iteration) |
 | `lib/parse-deps.sh` | Extracts dependency issue numbers from an issue body (stdin → stdout, one number per line). Matches `## Dependencies` / `## Depends on` / `## Blocked by` sections and inline `depends on #N` patterns. Not sourced — executed via `bash lib/parse-deps.sh`. | dev-poll, supervisor-poll |
 | `lib/matrix_listener.sh` | Long-poll Matrix sync daemon. Dispatches thread replies to the correct agent via well-known files (`/tmp/{agent}-escalation-reply`). Handles supervisor, gardener, dev, review, vault, and action reply routing. Run as systemd service. | Standalone daemon |
-| `lib/agent-session.sh` | Shared tmux + Claude session helpers: `create_agent_session()`, `inject_formula()`, `agent_wait_for_claude_ready()`, `agent_inject_into_session()`, `agent_kill_session()`, `monitor_phase_loop()`, `read_phase()`. `create_agent_session(session, workdir, [phase_file])` optionally installs a PostToolUse hook (matcher `Bash\|Write`) that detects phase file writes in real-time — when Claude writes to the phase file, the hook writes a marker so `monitor_phase_loop` reacts on the next poll instead of waiting for mtime changes. `monitor_phase_loop` sets `_MONITOR_LOOP_EXIT` to one of: `done`, `idle_timeout`, `idle_prompt` (Claude returned to `❯` for 3 consecutive polls without writing any phase — callback invoked with `PHASE:failed`, session already dead), `crashed`, or a `PHASE:*` string. Agents must handle `idle_prompt` in both their callback and their post-loop exit handler. | dev-agent.sh, gardener-agent.sh |
+| `lib/agent-session.sh` | Shared tmux + Claude session helpers: `create_agent_session()`, `inject_formula()`, `agent_wait_for_claude_ready()`, `agent_inject_into_session()`, `agent_kill_session()`, `monitor_phase_loop()`, `read_phase()`. `create_agent_session(session, workdir, [phase_file])` optionally installs a PostToolUse hook (matcher `Bash\|Write`) that detects phase file writes in real-time — when Claude writes to the phase file, the hook writes a marker so `monitor_phase_loop` reacts on the next poll instead of waiting for mtime changes. When `MATRIX_THREAD_ID` is exported, also installs a Stop hook (`on-stop-matrix.sh`) that streams each Claude response to the Matrix thread. `monitor_phase_loop` sets `_MONITOR_LOOP_EXIT` to one of: `done`, `idle_timeout`, `idle_prompt` (Claude returned to `❯` for 3 consecutive polls without writing any phase — callback invoked with `PHASE:failed`, session already dead), `crashed`, or a `PHASE:*` string. Agents must handle `idle_prompt` in both their callback and their post-loop exit handler. | dev-agent.sh, gardener-agent.sh |
 
 ---
 
diff --git a/action/action-agent.sh b/action/action-agent.sh
index 1793c21..f6e529b 100644
--- a/action/action-agent.sh
+++ b/action/action-agent.sh
@@ -96,6 +96,8 @@ THREAD_ID=""
 if [ -n "${_thread_id:-}" ]; then
   printf '%s' "$_thread_id" > "$THREAD_FILE"
   THREAD_ID="$_thread_id"
+  # Export for on-stop-matrix.sh hook (streams Claude output to thread)
+  export MATRIX_THREAD_ID="$_thread_id"
   # Register thread root in map for listener dispatch (column 4 = issue number)
   printf '%s\t%s\t%s\t%s\n' "$_thread_id" "action" "$(date +%s)" "${ISSUE}" \
     >> "${MATRIX_THREAD_MAP:-/tmp/matrix-thread-map}" 2>/dev/null || true
diff --git a/lib/agent-session.sh b/lib/agent-session.sh
index 1d797fe..806e137 100644
--- a/lib/agent-session.sh
+++ b/lib/agent-session.sh
@@ -120,6 +120,32 @@ create_agent_session() {
     fi
   fi
 
+  # Install Stop hook for Matrix streaming: when MATRIX_THREAD_ID is set,
+  # each Claude response is posted to the Matrix thread so humans can follow.
+  local matrix_hook_script="${FACTORY_ROOT}/lib/hooks/on-stop-matrix.sh"
+  if [ -n "${MATRIX_THREAD_ID:-}" ] && [ -x "$matrix_hook_script" ]; then
+    if [ -f "$settings" ]; then
+      jq --arg cmd "$matrix_hook_script" '
+        if (.hooks.Stop // [] | any(.[]; .hooks[]?.command == $cmd))
+        then .
+        else .hooks.Stop = (.hooks.Stop // []) + [{
+          matcher: "",
+          hooks: [{type: "command", command: $cmd}]
+        }]
+        end
+      ' "$settings" > "${settings}.tmp" && mv "${settings}.tmp" "$settings"
+    else
+      jq -n --arg cmd "$matrix_hook_script" '{
+        hooks: {
+          Stop: [{
+            matcher: "",
+            hooks: [{type: "command", command: $cmd}]
+          }]
+        }
+      }' > "$settings"
+    fi
+  fi
+
   rm -f "$idle_marker"
   tmux new-session -d -s "$session" -c "$workdir" \
     "claude --dangerously-skip-permissions" 2>/dev/null
diff --git a/lib/hooks/on-stop-matrix.sh b/lib/hooks/on-stop-matrix.sh
new file mode 100755
index 0000000..c85276b
--- /dev/null
+++ b/lib/hooks/on-stop-matrix.sh
@@ -0,0 +1,45 @@
+#!/bin/bash
+# on-stop-matrix.sh — Stop hook: post Claude response to Matrix thread.
+#
+# Called by Claude Code after each assistant turn. Reads the response from
+# the hook JSON and posts it to the Matrix thread for this action session.
+#
+# Requires env vars: MATRIX_THREAD_ID, MATRIX_TOKEN, MATRIX_HOMESERVER, MATRIX_ROOM_ID
+#
+# Usage (in .claude/settings.json):
+#   {"type": "command", "command": "/path/to/on-stop-matrix.sh"}
+
+# Exit early if Matrix thread not configured
+if [ -z "${MATRIX_THREAD_ID:-}" ] || [ -z "${MATRIX_TOKEN:-}" ] \
+   || [ -z "${MATRIX_HOMESERVER:-}" ] || [ -z "${MATRIX_ROOM_ID:-}" ]; then
+  cat > /dev/null
+  exit 0
+fi
+
+input=$(cat)
+
+# Extract response text from hook JSON
+response=$(printf '%s' "$input" | jq -r '.last_assistant_message // empty' 2>/dev/null)
+[ -z "$response" ] && exit 0
+
+# Truncate long output for readability (keep to ~4000 chars)
+MAX_LEN=4000
+if [ "${#response}" -gt "$MAX_LEN" ]; then
+  response="${response:0:$MAX_LEN}
+... [truncated]"
+fi
+
+# Post to Matrix thread
+room_encoded="${MATRIX_ROOM_ID//!/%21}"
+txn="$(date +%s%N)$$"
+
+body=$(jq -nc \
+  --arg m "$response" \
+  --arg t "$MATRIX_THREAD_ID" \
+  '{msgtype:"m.text",body:$m,"m.relates_to":{rel_type:"m.thread",event_id:$t}}')
+
+curl -s -X PUT \
+  -H "Authorization: Bearer ${MATRIX_TOKEN}" \
+  -H "Content-Type: application/json" \
+  "${MATRIX_HOMESERVER}/_matrix/client/v3/rooms/${room_encoded}/send/m.room.message/${txn}" \
+  -d "$body" > /dev/null 2>&1 || true