session reliability: reconnect, knowledge loop, retire request_execution

Phase 1 — crash recovery: SSE auto-reconnect + backoff, polling gate
during disconnect, connection banner with retry button, empty-response
retry 3x, non-terminal resume on empty response, persistent error cards.

Phase 2/4 — visibility + continuation: custom ExecutionStatus renderer,
approvals extracted on every tool_result (not just done), activity bar
with status/goal, SessionDigest live polling, Continue button.

Phase 3 — cleanup: complete_task auto-cancels orphaned approvals,
deletes assent/destructive window keys, propose_plan marks pending
steps as replaced, plan step seq-order enforcement.

Phase 5 — knowledge loop: list_lxcs state filter (active/destroyed),
SOUL.md unmissable writeback section, propose_plan validation nudge,
complete_task writeback check, upsert_knowledge about array support,
plan generation grouping in frontend, session approval count badge.

Retire request_execution — all mutations now route through run.
Updated SOUL.md, AGENTS.md, CLIENTS.md, skills, and agent system notes.

Migration 020: plan step generation column, audit_log session_id index,
nomos_plan_executions pending-approval index.

cmd/nomos/main.go

@@ -164,11 +164,29 @@ func handleChat(w http.ResponseWriter, r *http.Request, a *agent, st *store) {
 		http.Error(w, "bad request: "+err.Error(), 400)
 		return
 	}
-	if req.Message == "" {
+	if req.Message == "" && req.SessionID == "" {
 		http.Error(w, "message is required", 400)
 		return
 	}
 
+	// Empty message with an existing session = reconnect/resume. The
+	// frontend sends this after a dropped SSE stream to re-establish the
+	// connection and catch up on any auto-continuation work that happened
+	// while disconnected. Route into resumeSession so the agent sees a
+	// system note and reports current state.
+	if req.Message == "" && req.SessionID != "" {
+		slog.Info("nomos: reconnect", "session", req.SessionID)
+		safego.Go("nomos:reconnect:"+req.SessionID, func() {
+			note := "[System: the operator's connection was re-established. The task may have progressed in the background — report your current state and progress.]"
+			a.resumeSession(context.Background(), req.SessionID, note)
+		})
+		// Return 202 so the frontend doesn't try to consume an SSE stream
+		// from this POST — resumeSession writes to the DB directly and
+		// the poller (already running from handleDisconnect) picks it up.
+		w.WriteHeader(202)
+		return
+	}
+
 	flusher, ok := w.(http.Flusher)
 	if !ok {
 		http.Error(w, "streaming not supported", 500)
@@ -318,6 +336,14 @@ func handleSessionDetail(w http.ResponseWriter, r *http.Request, st *store, a *a
 		return
 	}
 
+	// POST /sessions/{id}/resume — the operator asks the agent to continue.
+	if len(parts) == 2 && parts[1] == "resume" && r.Method == http.MethodPost {
+		note := "[System: the operator wants you to continue. Pick up where you left off — execute the next step of the plan, diagnose and fix any failures, or report progress if everything is done.]"
+		safego.Go("nomos:resume-session", func() { a.resumeSession(context.Background(), id, note) })
+		w.WriteHeader(202)
+		return
+	}
+
 	// GET /sessions/{id}/plan and /sessions/{id}/questions — REST hydration for
 	// the context panel when it first opens a task; live events carry deltas
 	// from there.