feat(nomos): session-review improvements (P0/P1/P2 from 2026-07-20 audit)

Classifier now unwraps pct exec / qm guest exec / bash -c / sh -c / sudo
and env-var assignments before classification, so read-only inspection
wrapped in pct exec no longer escalates to config_mutation. curl GET
(default method, no -d/-F/-T/-o/>) is read-only. Eliminates the three
duplicate rclone sessions (a51e2086, 8acea2e3, cb8c8a4a) that bounced
off the classifier for the same goal.

New classify_command MCP tool: command-scoped preflight that returns the
exact risk class run would assign. Documented in SOUL.md with guidance
to pre-classify before run when the verdict is uncertain.

set_goal surfaces prior partial/failed sessions from the last 24h so the
agent picks up the thread instead of rediscovering it.

completeTask auto-closes in-flight plan steps (pending/running -> done
on success, skipped on partial/failure), so one-step plans no longer
need the per-step running->done dance right before completion.

Migration 021 adds blocker + closed_at to agent_sessions. completeTask
sets closed_at once and derives a structured blocker reason
(approval_timeout, user_abandoned, classifier_overreach, model_refusal,
tool_error, ...) from the last assistant message.

/sessions list now carries message_count, tool_call_count,
duration_seconds (server-side aggregates — no more N+1 transcript
fetches to audit a fleet). GET /sessions/{id} returns both metadata
and messages. New query params filter + paginate: outcome, status,
entity_id, blocker, since (RFC3339 or Go duration), cursor, limit.

Titles now prefer the goal when set; sessions without a goal fall back
to the first assistant text.

New GET /sessions/{id}/tool_calls flat view for audit scripts.

Plan: plans/2026-07-20-session-review-ten-sessions.md. VERSION 0.7.12 -> 0.7.13.

internal/mcp/tools.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/dtoro/oikos/internal/db"
+	"github.com/dtoro/oikos/internal/policy"
 	"github.com/google/uuid"
 	"github.com/modelcontextprotocol/go-sdk/mcp"
 )
@@ -704,6 +705,48 @@ func allTools(pool *db.Pool, agentID uuid.UUID) []toolReg {
 			FROM entities e WHERE e.slug = $1`, slug, action), nil
 		}},
 
+		// classify_command is the command-scoped preflight from
+		// plans/2026-07-20-session-review-ten-sessions.md P0.2. The
+		// existing `preflight` tool is entity/action-scoped — useless when
+		// the agent is composing a `run` command and needs to know whether
+		// the classifier will accept it before submitting. Without this,
+		// the agent has to retry with cosmetic variations until it finds
+		// one that passes (see sessions a51e2086, 8acea2e3 — three
+		// duplicate rclone sessions, all bouncing off the classifier).
+		// Call this BEFORE `run` whenever the classification is uncertain.
+		{tool: &mcp.Tool{Name: "classify_command", Description: "Pre-flight risk classification for a shell command BEFORE calling run. Returns the risk class (read_only / reversible_low / config_mutation / destructive) that `run` would assign. Use this when you're unsure whether a command will auto-execute or need approval — e.g. `pct exec`, `curl`, compound commands, or anything that might be mistaken for mutation. If this returns read_only, the same command will auto-execute via run with no approval; if it returns config_mutation, expect to need operator approval (or pre-frame the command so it classifies lower). Declared risk can only escalate, never de-escalate.",
+			InputSchema: objSchema(
+				prop{"command", "string", "The exact shell command you intend to pass to run."},
+				prop{"declared_risk", "string", "Optional self-assessment you would pass to run (read_only, reversible_low, config_mutation, destructive). Mirrors run's declared_risk parameter."},
+			),
+		}, handler: func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+			args := argsMap(req)
+			command, _ := args["command"].(string)
+			declaredRisk, _ := args["declared_risk"].(string)
+			if command == "" {
+				return textResult("error: command is required"), nil
+			}
+			risk := policy.ClassifyCommand(command, declaredRisk)
+			note := ""
+			switch risk {
+			case policy.RiskReadOnly:
+				note = "auto-acts on `run` (no approval needed)."
+			case policy.RiskReversibleLow:
+				note = "auto-acts on `run` (no approval needed)."
+			case policy.RiskConfigMutation:
+				note = "requires operator approval on `run` (or loose assent window active)."
+			case policy.RiskDestructive:
+				note = "requires explicit operator confirmation on `run` (typed \"I confirm\" phrase)."
+			}
+			out, _ := json.Marshal(map[string]any{
+				"command":       command,
+				"declared_risk": declaredRisk,
+				"risk_class":    risk,
+				"note":          note,
+			})
+			return textResult(string(out)), nil
+		}},
+
 		{tool: &mcp.Tool{Name: "get_change_history", Description: "Last N change-ledger entries for an entity",
 			InputSchema: objSchema(
 				prop{"entity_slug", "string", "Entity slug"},