feat(agent): plan-first gate, iterative follow-ups, reasoning persistence

P1 plan-first: run handler refuses without propose_plan (structural gate,
not SOUL.md prose). Plan window decoupled from set_goal — config_mutation
auto-run only on operator approval (assent window). Closes the approval-free
config_mutation hole confirmed in session d0d562e0.

P2 iteration: reopenSession flips terminal→executing, marks prior plan steps
replaced, clears outcome. proposePlan excludes replaced from in-flight check,
bumps generation. A follow-up on a completed session starts a new sub-task
with a fresh plan — no more errPlanInFlight dead end.

P3 reasoning: accumulate per-iteration text into the persisted row instead
of overwriting with the last text event. Reload shows intermediate thinking,
not just the final summary.

P4 read-only allowlist: add find, tree, locate, systemctl list-timers/
list-unit-files/show, timedatectl, hostnamectl, systemd-analyze, rclone
ls/lsl/md5sum/check/cryptcheck. Fixes the find misclassification from
d0d562e0.

P5 eval harness: new assertion kinds (proposes_plan, plan_before_run,
plan_generations), multi-turn followups, fetch /sessions/{id}/plan. Four
manifests under evals/.

P6 SOUL.md: strip degenerate-case carve-out, add ITERATE step, update
set_goal guidance.

VERSION 0.6.0 → 0.7.0

cmd/nomos/eval/main.go

@@ -125,8 +125,8 @@ func runConversation(ctx context.Context, gateway string, c conversation, timeou
 	}
 
 	// Send followup if any.
-	if c.Followup != "" {
-		if _, err := sendChat(ctx, gateway, sid, c.Followup); err != nil {
+	for _, fu := range c.followups() {
+		if _, err := sendChat(ctx, gateway, sid, fu); err != nil {
 			res.Assertions = []assertionResult{{Name: "send_followup", Passed: false, Detail: err.Error()}}
 			res.Duration = time.Since(start)
 			return res
@@ -246,6 +246,19 @@ type transcript struct {
 			ToolCalls []map[string]any  `json:"tool_calls"`
 		} `json:"content"`
 	} `json:"messages"`
+	// PlanSteps is fetched from /sessions/{id}/plan (P5 plan_generations
+	// assertion). Each step carries a `generation` int; distinctGenerations
+	// counts the unique values. nil when the endpoint returned no plan
+	// (e.g. a pure-DB Q&A with no propose_plan call).
+	PlanSteps []planStep `json:"steps"`
+}
+
+// planStep is one step from /sessions/{id}/plan, carrying only the fields the
+// eval needs: the generation number (P2 iteration counter).
+type planStep struct {
+	Generation int    `json:"generation"`
+	Status     string `json:"status"`
+	Title      string `json:"title"`
 }
 
 func (t transcript) toolCallCount() int {
@@ -268,6 +281,17 @@ func (t transcript) toolNames() []string {
 	return names
 }
 
+// distinctGenerations counts unique plan generation values across all plan
+// steps. Used by the `plan_generations` assertion (P2 iteration). Returns 0
+// when there are no plan steps (no propose_plan was called).
+func (t transcript) distinctGenerations() int {
+	seen := map[int]bool{}
+	for _, s := range t.PlanSteps {
+		seen[s.Generation] = true
+	}
+	return len(seen)
+}
+
 type sessionState struct {
 	ID         string `json:"id"`
 	Status     string `json:"status"`
@@ -277,7 +301,8 @@ type sessionState struct {
 
 // fetchTranscript fetches the messages from /sessions/{id} (which returns
 // only session_id + messages) and the session metadata from /sessions
-// (which returns status/outcome/last_active_at for each session).
+// (which returns status/outcome/last_active_at for each session). P5 also
+// fetches /sessions/{id}/plan for the plan_generations assertion.
 func fetchTranscript(ctx context.Context, gateway, sid string) (transcript, sessionState, error) {
 	var t transcript
 	resp, err := http.Get(gateway + "/sessions/" + sid)
@@ -292,6 +317,16 @@ func fetchTranscript(ctx context.Context, gateway, sid string) (transcript, sess
 	if err := json.Unmarshal(b, &t); err != nil {
 		return t, sessionState{}, err
 	}
+	// Fetch the plan (steps with generation numbers) for the
+	// plan_generations assertion. A 404 or empty response is fine — a
+	// pure-DB Q&A with no propose_plan has no plan.
+	if planResp, perr := http.Get(gateway + "/sessions/" + sid + "/plan"); perr == nil {
+		if planResp.StatusCode == 200 {
+			pb, _ := io.ReadAll(planResp.Body)
+			_ = json.Unmarshal(pb, &t) // fills t.PlanSteps via "steps" field
+		}
+		planResp.Body.Close()
+	}
 	// The detail endpoint doesn't return status/outcome — fetch from the
 	// sessions list and find the matching id.
 	s, err := fetchSessionMeta(ctx, gateway, sid)