fix(nomos): sessions blocked on an execution approval now show "Needs input" and never idle-close

A config_mutation/destructive run() queued for approval never touched
agent_sessions.status — only ask_operator did that, setting
awaiting_input. So a task blocked on an execution approval was
indistinguishable from one still genuinely working: the frontend's
"Needs input" bucket only checks status===awaiting_input (never lit
up for these), and the idle-sweep safety net only excludes
awaiting_input from its stale-task query, so after ~30 minutes idle
it would nudge the agent and then auto-close the task with
outcome=partial while the approval was still sitting there undecided.

classifyAndGate now flips the session into awaiting_input the moment
an execution is queued (internal/mcp/server.go), and DecideApproval
flips it back to executing once the approval is approved, denied, or
revoked (internal/httpapi/approvals.go) — mirroring askOperator /
answerQuestion's existing pattern for session_questions. Both emit
task.status so the board updates live.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

internal/mcp/server.go

@@ -778,6 +778,7 @@ func classifyAndGate(ctx context.Context, pool *db.Pool, agentID, targetID uuid.
 
 	pool.Exec(ctx, `UPDATE executions SET status='pending_approval', risk_class=$2 WHERE entity_id=$1`, id, riskClass)
 	createApproval(ctx, pool, id, targetID, "run", string(runParams), riskClass)
+	markSessionAwaitingApproval(ctx, pool, sessionID)
 	confirmNote := ""
 	if riskClass == policy.RiskDestructive {
 		confirmNote = " This is classified DESTRUCTIVE — flag that clearly to the operator; it needs explicit confirmation, not just a casual \"go ahead\"."
@@ -1065,6 +1066,49 @@ func createApproval(ctx context.Context, pool *db.Pool, execID, targetID uuid.UU
 		map[string]any{"action": action, "params": params, "risk_class": riskClass})
 }
 
+// markSessionAwaitingApproval flips a session to awaiting_input the moment
+// one of its gated executions is queued for approval — mirrors what
+// askOperator does for session_questions (cmd/nomos/store.go's askOperator),
+// so a pending execution approval reads as "needs input" to both the
+// frontend's Overview board (which only checks agent_sessions.status) and
+// the idle-sweep safety net (staleGoalSessions, cmd/nomos/store.go, which
+// already excludes awaiting_input from its stale-task sweep). Before this, a
+// task blocked on a config_mutation/destructive approval just sat at
+// 'executing' — indistinguishable from a task still genuinely working — so
+// the idle sweep would eventually nudge it and then auto-close it with
+// outcome=partial while the approval was still sitting there undecided.
+// The httpapi package's DecideApproval flips the session back out once the
+// approval is approved/denied/revoked (internal/httpapi/approvals.go).
+//
+// No-op for sessionID=="" (a direct MCP call with no nomos session) or a
+// session that's already terminal/already awaiting_input — the status IN
+// guard makes this safe to call unconditionally from classifyAndGate.
+func markSessionAwaitingApproval(ctx context.Context, pool *db.Pool, sessionID string) {
+	if sessionID == "" || sessionID == "ephemeral" {
+		return
+	}
+	tag, err := pool.Exec(ctx, `
+		UPDATE agent_sessions SET status = 'awaiting_input', last_active_at = now()
+		WHERE id = $1 AND status IN ('active', 'planning', 'executing')`, sessionID)
+	if err != nil || tag.RowsAffected() == 0 {
+		return
+	}
+	_ = observability.Event(ctx, sqlcgen.New(pool), "task.status", sessionTaskEntity(ctx, pool, sessionID),
+		"info", "nomos", sessionID, map[string]any{"status": "awaiting_input", "reason": "execution_pending_approval"})
+}
+
+// sessionTaskEntity resolves a session's own task-entity id, for anchoring
+// events to the right node in the graph — mirrors cmd/nomos/store.go's
+// (unexported) taskEntityPtr; duplicated here since that's a different
+// package's private method.
+func sessionTaskEntity(ctx context.Context, pool *db.Pool, sessionID string) *uuid.UUID {
+	var id uuid.UUID
+	if err := pool.QueryRow(ctx, `SELECT entity_id FROM agent_sessions WHERE id = $1`, sessionID).Scan(&id); err != nil || id == uuid.Nil {
+		return nil
+	}
+	return &id
+}
+
 // inspectPathAcrossTargets is the bulk fact-gathering helper behind the
 // inspect_path MCP tool (plans/2026-07-18-session-review-three-sessions.md
 // P1.5). For each target slug, it runs a single read-only shell command