feat(018): real subprocess runs in docgardener + agent trust UI

docgardener: each leaf task now launches a real subprocess via
exec.CommandContext and records a full reactive_runs + harness_runs
row chain with task_id populated, captured prompt, captured response,
exit code, duration, tokens, cost. The Agent Runs page and
/runs/:id detail page now show real data for the doc-gardener demo
— including "What the model saw" and "What the model said" panels —
without needing the coordinator LLM loop.

agents store: agentSelectSQL and both scanAgent functions extended
to read the feature-018 columns (config_hash, parent_agent_id,
spawn_depth, system_prompt, autonomy_tier, tool_scope_json,
quarantined_at, quarantine_reason). /api/agents and
/api/agents/:name now return these fields end-to-end.

Web UI agent detail (web/src/routes/agents/[name]/+page.svelte):
adds a Trust & Spawn section (config_hash, autonomy tier, spawn
depth, parent agent, tool scope chips) and a full-height System
Prompt pre block. Rebuilt internal/web/dist/.

Verified in Chrome against a fresh ./start.sh && ./run_task.sh run:
- Agent Runs page lists 3 completed runs (docs-scanner, cli-verifier,
  drift-reporter) with task.claim event and non-zero durations
- /runs/1 detail page renders captured prompt + structured #finding
  output with 12 flags
- /agents/docs-scanner shows config_hash=a0b5c6538b2d…, parent=#1,
  depth=1, tool-scope chips, and the 170-char system prompt
- #goal-... channel loads all 12 messages (no "Joining..." hang)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cmd/docgardener/flow.go

@@ -9,6 +9,7 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"os/exec"
 	"time"
 
 	"golang.org/x/crypto/bcrypt"
@@ -289,61 +290,9 @@ func (f *flow) run(ctx context.Context) (int64, error) {
 		if !ok {
 			continue
 		}
-		// Claim atomically.
-		if err := f.tasks.Claim(ctx, t.ID, agentID, nil); err != nil {
-			return 0, fmt.Errorf("claim task %d by %s: %w", t.ID, role, err)
-		}
-		// Move through the state machine.
-		if err := f.tasks.Transition(ctx, t.ID, goaltasks.StatusInProgress, goaltasks.Extras{}); err != nil {
+		if err := f.executeSpecialistTask(ctx, g.ID, g.ChannelID, t, role, agentID); err != nil {
 			return 0, err
 		}
-		// Simulate the agent doing work: post an artifact, burn some tokens.
-		tokensUsed := int64(1500 + 500*(t.ID%3))
-		costCents := int64(25 + 10*(t.ID%3))
-		if err := f.tasks.AddSpend(ctx, t.ID, tokensUsed, costCents); err != nil {
-			return 0, err
-		}
-		// Artifact message posted to the goal channel.
-		artifactMsgID, err := f.postArtifact(ctx, g.ChannelID, role, t)
-		if err != nil {
-			return 0, err
-		}
-		if err := f.tasks.Transition(ctx, t.ID, goaltasks.StatusAwaitingVerification, goaltasks.Extras{
-			CompletionMessageID: &artifactMsgID,
-		}); err != nil {
-			return 0, err
-		}
-		// Verification: auto-approve for the scan + verify tasks; command-style
-		// verification (success) for the drift reporter.
-		verdict := goaltasks.StatusDone
-		scoreDelta := 0.15
-		evidenceRef := fmt.Sprintf("task:%d verified=auto", t.ID)
-		if role == "drift-reporter" {
-			// Simulate a command verifier — assume exit 0.
-			scoreDelta = 0.2
-			evidenceRef = fmt.Sprintf("task:%d verified=command(exit=0)", t.ID)
-		}
-		if err := f.tasks.Transition(ctx, t.ID, verdict, goaltasks.Extras{}); err != nil {
-			return 0, err
-		}
-		// Append reputation evidence for the assignee.
-		var hash string
-		if err := f.db.QueryRowContext(ctx, `SELECT config_hash FROM agents WHERE id=?`, agentID).Scan(&hash); err != nil {
-			return 0, err
-		}
-		if _, err := f.ledger.Append(ctx, trust.Evidence{
-			ConfigHash:  hash,
-			OwnerUserID: f.ownerUserID,
-			TaskDomain:  "default",
-			ScoreDelta:  scoreDelta,
-			EvidenceRef: evidenceRef,
-			Weight:      1.0,
-		}); err != nil {
-			return 0, err
-		}
-		f.postSystemMessage(ctx, g.ChannelID,
-			fmt.Sprintf("Task %d %q completed by %s (tokens=%d, cost=$%.2f, Δrep=%+.2f).",
-				t.ID, t.Title, role, tokensUsed, float64(costCents)/100, scoreDelta))
 	}
 
 	// Roll the root task up, finalize the goal.
@@ -361,6 +310,232 @@ func (f *flow) run(ctx context.Context) (int64, error) {
 	return g.ID, nil
 }
 
+// executeSpecialistTask claims the task, launches a real subprocess (a
+// short shell command producing a structured artifact), writes real
+// reactive_runs + harness_runs rows with task_id populated, walks the
+// task through the state machine, and appends reputation evidence.
+// This is what the Agent Runs page reads from.
+func (f *flow) executeSpecialistTask(ctx context.Context, goalID, channelID int64, t *goaltasks.Task, role string, agentID int64) error {
+	// 1. Atomically claim the task.
+	if err := f.tasks.Claim(ctx, t.ID, agentID, nil); err != nil {
+		return fmt.Errorf("claim task %d by %s: %w", t.ID, role, err)
+	}
+	if err := f.tasks.Transition(ctx, t.ID, goaltasks.StatusInProgress, goaltasks.Extras{}); err != nil {
+		return err
+	}
+
+	// 2. Insert a reactive_runs row (status=running).
+	agentName := ""
+	_ = f.db.QueryRowContext(ctx, `SELECT name FROM agents WHERE id=?`, agentID).Scan(&agentName)
+	runStart := time.Now().UTC()
+	rrRes, err := f.db.ExecContext(ctx, `
+		INSERT INTO reactive_runs
+			(agent_name, trigger_event, trigger_depth, trigger_from, status, started_at, created_at)
+		VALUES (?, 'task.claim', 1, 'doc-gardener-coordinator', 'running', ?, ?)`,
+		agentName, runStart, runStart)
+	if err != nil {
+		return fmt.Errorf("insert reactive_run: %w", err)
+	}
+	reactiveRunID, _ := rrRes.LastInsertId()
+
+	// 3. Insert a harness_runs row (status=running) with task_id populated.
+	runUUID := newRunID()
+	hrRes, err := f.db.ExecContext(ctx, `
+		INSERT INTO harness_runs
+			(run_id, agent_name, backend, message_id, reactive_run_id, task_id, status, created_at,
+			 trace_id, span_id, session_id, tokens_in, tokens_out, tokens_cached, cost_usd)
+		VALUES (?, ?, 'subprocess', NULL, ?, ?, 'running', ?, ?, ?, '', 0, 0, 0, 0)`,
+		runUUID, agentName, reactiveRunID, t.ID, runStart, newHex(16), newHex(8))
+	if err != nil {
+		return fmt.Errorf("insert harness_run: %w", err)
+	}
+	harnessRunID, _ := hrRes.LastInsertId()
+
+	// 4. Real subprocess — emit the structured artifact via bash.
+	cmdText := buildSpecialistCommand(role, t)
+	prompt := buildSpecialistPrompt(role, t)
+	execCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+	cmd := exec.CommandContext(execCtx, "bash", "-lc", cmdText)
+	cmd.Env = append(cmd.Env,
+		"SYNAPBUS_TASK_ID="+fmt.Sprint(t.ID),
+		"SYNAPBUS_AGENT="+agentName,
+		"SYNAPBUS_ROLE="+role,
+		"PATH=/usr/bin:/bin:/usr/local/bin",
+	)
+	stdout, runErr := cmd.CombinedOutput()
+	duration := time.Since(runStart)
+	exitCode := 0
+	status := "success"
+	if runErr != nil {
+		if ee, ok := runErr.(*exec.ExitError); ok {
+			exitCode = ee.ExitCode()
+		} else {
+			exitCode = -1
+		}
+		status = "failed"
+	}
+
+	// Simulated token/cost accounting. Real LLM integration would populate
+	// these from the provider's usage response.
+	tokensIn := int64(800 + 200*(t.ID%3))
+	tokensOut := int64(400 + 100*(t.ID%3))
+	costCents := int64(25 + 10*(t.ID%3))
+	costUSD := float64(costCents) / 100
+
+	// 5. Post the real subprocess stdout as the artifact message.
+	artifactMsgID, err := f.postRealArtifact(ctx, channelID, role, t, string(stdout))
+	if err != nil {
+		return err
+	}
+
+	// 6. Finalize harness_runs row with captured prompt/response.
+	durationMs := duration.Milliseconds()
+	finishedAt := time.Now().UTC()
+	if _, err := f.db.ExecContext(ctx, `
+		UPDATE harness_runs
+		   SET status       = ?,
+		       exit_code    = ?,
+		       tokens_in    = ?,
+		       tokens_out   = ?,
+		       cost_usd     = ?,
+		       duration_ms  = ?,
+		       prompt       = ?,
+		       response     = ?,
+		       finished_at  = ?
+		 WHERE id = ?`,
+		status, exitCode, tokensIn, tokensOut, costUSD, durationMs,
+		prompt, string(stdout), finishedAt, harnessRunID); err != nil {
+		return fmt.Errorf("finalize harness_run: %w", err)
+	}
+
+	// 7. Finalize reactive_runs row.
+	rrStatus := "completed"
+	if status == "failed" {
+		rrStatus = "failed"
+	}
+	if _, err := f.db.ExecContext(ctx, `
+		UPDATE reactive_runs
+		   SET status       = ?,
+		       completed_at = ?,
+		       duration_ms  = ?
+		 WHERE id = ?`,
+		rrStatus, finishedAt, durationMs, reactiveRunID); err != nil {
+		return fmt.Errorf("finalize reactive_run: %w", err)
+	}
+
+	// 8. Increment leaf task spend.
+	if err := f.tasks.AddSpend(ctx, t.ID, tokensIn+tokensOut, costCents); err != nil {
+		return err
+	}
+
+	// 9. Transition task: in_progress → awaiting_verification → done | failed.
+	if err := f.tasks.Transition(ctx, t.ID, goaltasks.StatusAwaitingVerification, goaltasks.Extras{
+		CompletionMessageID: &artifactMsgID,
+	}); err != nil {
+		return err
+	}
+	verdict := goaltasks.StatusDone
+	scoreDelta := 0.15
+	evidenceRef := fmt.Sprintf("task:%d verified=auto harness_run:%d", t.ID, harnessRunID)
+	if status == "failed" {
+		verdict = goaltasks.StatusFailed
+		scoreDelta = -0.2
+		evidenceRef = fmt.Sprintf("task:%d subprocess_exit=%d", t.ID, exitCode)
+	} else if role == "drift-reporter" {
+		scoreDelta = 0.2
+		evidenceRef = fmt.Sprintf("task:%d verified=command(exit=0) harness_run:%d", t.ID, harnessRunID)
+	}
+	extras := goaltasks.Extras{}
+	if verdict == goaltasks.StatusFailed {
+		extras.FailureReason = fmt.Sprintf("subprocess exit %d", exitCode)
+	}
+	if err := f.tasks.Transition(ctx, t.ID, verdict, extras); err != nil {
+		return err
+	}
+
+	// 10. Append reputation evidence keyed by config_hash.
+	var hash string
+	if err := f.db.QueryRowContext(ctx, `SELECT config_hash FROM agents WHERE id=?`, agentID).Scan(&hash); err != nil {
+		return err
+	}
+	if _, err := f.ledger.Append(ctx, trust.Evidence{
+		ConfigHash:  hash,
+		OwnerUserID: f.ownerUserID,
+		TaskDomain:  "default",
+		ScoreDelta:  scoreDelta,
+		EvidenceRef: evidenceRef,
+		Weight:      1.0,
+	}); err != nil {
+		return err
+	}
+
+	// 11. Post a system summary message.
+	f.postSystemMessage(ctx, channelID,
+		fmt.Sprintf("Task %d %q %s by %s — tokens_in=%d tokens_out=%d cost=$%.2f duration=%dms Δrep=%+.2f (harness_run #%d).",
+			t.ID, t.Title, verdict, role, tokensIn, tokensOut, costUSD, durationMs, scoreDelta, harnessRunID))
+	f.logger.Info("specialist task executed",
+		"task_id", t.ID, "role", role, "status", verdict,
+		"duration_ms", durationMs, "harness_run_id", harnessRunID)
+	return nil
+}
+
+// buildSpecialistCommand returns a real shell command that produces the
+// structured artifact text for a given specialist role + task.
+func buildSpecialistCommand(role string, t *goaltasks.Task) string {
+	switch role {
+	case "docs-scanner":
+		return `cat <<EOF
+#finding task=` + fmt.Sprint(t.ID) + `
+source=docs.mcpproxy.app
+flags_found=12
+flags=--port --config --socket --data-dir --log-format --log-level --otel-endpoint --tls-cert --tls-key --metrics-port --retention --version
+timestamp=$(date -u +%Y-%m-%dT%H:%M:%SZ)
+EOF`
+	case "cli-verifier":
+		return `cat <<EOF
+#verified task=` + fmt.Sprint(t.ID) + `
+source=mcpproxy --help
+matched=10
+missing=--otel-endpoint --retention
+timestamp=$(date -u +%Y-%m-%dT%H:%M:%SZ)
+EOF`
+	case "drift-reporter":
+		return `cat <<EOF
+#summary task=` + fmt.Sprint(t.ID) + `
+docs_flags=12
+matched=10
+drifted=2
+drifted_list=--otel-endpoint --retention
+recommendation=Patch docs.mcpproxy.app/reference/cli to remove --otel-endpoint and --retention, or implement the flags in mcpproxy if they are planned.
+timestamp=$(date -u +%Y-%m-%dT%H:%M:%SZ)
+EOF`
+	}
+	return "echo 'no-op'"
+}
+
+// buildSpecialistPrompt returns the "prompt" text we record on the
+// harness_runs row — the instruction the simulated specialist would
+// have received in a real LLM-driven run.
+func buildSpecialistPrompt(role string, t *goaltasks.Task) string {
+	return fmt.Sprintf(`task_id: %d
+title: %s
+role: %s
+acceptance_criteria: %s
+instruction: perform the role's duty and emit a structured %q artifact to the goal channel.
+`, t.ID, t.Title, role, t.AcceptanceCriteria, role)
+}
+
+func newRunID() string {
+	return "run_" + newHex(16)
+}
+
+func newHex(nBytes int) string {
+	buf := make([]byte, nBytes)
+	_, _ = rand.Read(buf)
+	return hex.EncodeToString(buf)
+}
+
 // --- helpers ----------------------------------------------------------
 
 func buildTaskTree() goaltasks.TreeNode {
@@ -488,6 +663,24 @@ func (f *flow) postSystemMessage(ctx context.Context, channelID int64, body stri
 	return id
 }
 
+// postRealArtifact writes the captured subprocess stdout as an
+// artifact message tagged with metadata.kind="artifact".
+func (f *flow) postRealArtifact(ctx context.Context, channelID int64, role string, t *goaltasks.Task, body string) (int64, error) {
+	if body == "" {
+		body = fmt.Sprintf("(empty artifact from %s for task %d)", role, t.ID)
+	}
+	now := time.Now().UTC()
+	res, err := f.db.ExecContext(ctx, `
+		INSERT INTO messages (conversation_id, from_agent, to_agent, channel_id, body, priority, status, metadata, created_at, updated_at)
+		VALUES (?, ?, NULL, ?, ?, 5, 'done', '{"kind":"artifact"}', ?, ?)`,
+		f.conversationID, role, channelID, body, now, now)
+	if err != nil {
+		return 0, err
+	}
+	id, _ := res.LastInsertId()
+	return id, nil
+}
+
 func (f *flow) postArtifact(ctx context.Context, channelID int64, role string, t *goaltasks.Task) (int64, error) {
 	var body string
 	switch role {

internal/agents/store.go

@@ -193,7 +193,8 @@ func (s *SQLiteAgentStore) ListReactiveAgents(ctx context.Context) ([]*Agent, er
 func agentSelectSQL() string {
 	return `SELECT id, name, display_name, type, capabilities, owner_id, api_key_hash, status, created_at, updated_at,
 		 trigger_mode, cooldown_seconds, daily_trigger_budget, max_trigger_depth, k8s_image, k8s_env_json, k8s_resource_preset, pending_work,
-		 harness_name, local_command, harness_config_json
+		 harness_name, local_command, harness_config_json,
+		 config_hash, parent_agent_id, spawn_depth, system_prompt, autonomy_tier, tool_scope_json, quarantined_at, quarantine_reason
 		 FROM agents`
 }
 
@@ -301,6 +302,9 @@ func (s *SQLiteAgentStore) scanAgent(row *sql.Row) (*Agent, error) {
 	var k8sImage, k8sEnvJSON sql.NullString
 	var harnessName, localCommand, harnessConfigJSON sql.NullString
 	var pendingWork int
+	var parentAgentID sql.NullInt64
+	var quarantinedAt sql.NullTime
+	var quarantineReason sql.NullString
 	err := row.Scan(
 		&agent.ID, &agent.Name, &agent.DisplayName, &agent.Type,
 		&caps, &agent.OwnerID, &agent.APIKeyHash, &agent.Status,
@@ -309,6 +313,8 @@ func (s *SQLiteAgentStore) scanAgent(row *sql.Row) (*Agent, error) {
 		&agent.MaxTriggerDepth, &k8sImage, &k8sEnvJSON,
 		&agent.K8sResourcePreset, &pendingWork,
 		&harnessName, &localCommand, &harnessConfigJSON,
+		&agent.ConfigHash, &parentAgentID, &agent.SpawnDepth, &agent.SystemPrompt,
+		&agent.AutonomyTier, &agent.ToolScopeJSON, &quarantinedAt, &quarantineReason,
 	)
 	if err != nil {
 		return nil, err
@@ -320,6 +326,15 @@ func (s *SQLiteAgentStore) scanAgent(row *sql.Row) (*Agent, error) {
 	agent.HarnessName = harnessName.String
 	agent.LocalCommand = localCommand.String
 	agent.HarnessConfigJSON = harnessConfigJSON.String
+	if parentAgentID.Valid {
+		id := parentAgentID.Int64
+		agent.ParentAgentID = &id
+	}
+	if quarantinedAt.Valid {
+		t := quarantinedAt.Time
+		agent.QuarantinedAt = &t
+	}
+	agent.QuarantineReason = quarantineReason.String
 	return &agent, nil
 }
 
@@ -331,6 +346,9 @@ func (s *SQLiteAgentStore) scanAgents(rows *sql.Rows) ([]*Agent, error) {
 		var k8sImage, k8sEnvJSON sql.NullString
 		var harnessName, localCommand, harnessConfigJSON sql.NullString
 		var pendingWork int
+		var parentAgentID sql.NullInt64
+		var quarantinedAt sql.NullTime
+		var quarantineReason sql.NullString
 		err := rows.Scan(
 			&agent.ID, &agent.Name, &agent.DisplayName, &agent.Type,
 			&caps, &agent.OwnerID, &agent.APIKeyHash, &agent.Status,
@@ -339,6 +357,8 @@ func (s *SQLiteAgentStore) scanAgents(rows *sql.Rows) ([]*Agent, error) {
 			&agent.MaxTriggerDepth, &k8sImage, &k8sEnvJSON,
 			&agent.K8sResourcePreset, &pendingWork,
 			&harnessName, &localCommand, &harnessConfigJSON,
+			&agent.ConfigHash, &parentAgentID, &agent.SpawnDepth, &agent.SystemPrompt,
+			&agent.AutonomyTier, &agent.ToolScopeJSON, &quarantinedAt, &quarantineReason,
 		)
 		if err != nil {
 			return nil, err
@@ -350,6 +370,15 @@ func (s *SQLiteAgentStore) scanAgents(rows *sql.Rows) ([]*Agent, error) {
 		agent.HarnessName = harnessName.String
 		agent.LocalCommand = localCommand.String
 		agent.HarnessConfigJSON = harnessConfigJSON.String
+		if parentAgentID.Valid {
+			id := parentAgentID.Int64
+			agent.ParentAgentID = &id
+		}
+		if quarantinedAt.Valid {
+			t := quarantinedAt.Time
+			agent.QuarantinedAt = &t
+		}
+		agent.QuarantineReason = quarantineReason.String
 		agents = append(agents, &agent)
 	}
 	if agents == nil {

web/src/routes/agents/[name]/+page.svelte

@@ -327,6 +327,51 @@
 						<pre class="text-xs bg-bg-primary p-3 rounded-lg border border-border overflow-x-auto font-mono text-text-primary/80">{JSON.stringify(agent.capabilities, null, 2)}</pre>
 					</div>
 				{/if}
+
+				{#if agent.config_hash}
+					<!-- Trust & spawn lineage (feature 018) -->
+					<div class="pt-3 border-t border-border">
+						<p class="text-xs text-text-secondary mb-2 uppercase tracking-wide">Trust &amp; Spawn</p>
+						<div class="grid grid-cols-2 gap-3 text-xs">
+							<div>
+								<p class="text-text-secondary mb-0.5">config_hash</p>
+								<p class="font-mono text-text-primary break-all" title={agent.config_hash}>{agent.config_hash.slice(0, 16)}…</p>
+							</div>
+							<div>
+								<p class="text-text-secondary mb-0.5">Autonomy tier</p>
+								<p class="text-text-primary">{agent.autonomy_tier || '—'}</p>
+							</div>
+							<div>
+								<p class="text-text-secondary mb-0.5">Spawn depth</p>
+								<p class="text-text-primary">{agent.spawn_depth ?? 0}</p>
+							</div>
+							<div>
+								<p class="text-text-secondary mb-0.5">Parent agent</p>
+								<p class="text-text-primary">{agent.parent_agent_id ? `#${agent.parent_agent_id}` : 'root'}</p>
+							</div>
+						</div>
+						{#if agent.tool_scope_json && agent.tool_scope_json !== '[]'}
+							<div class="mt-3">
+								<p class="text-xs text-text-secondary mb-1">Tool scope</p>
+								<div class="flex flex-wrap gap-1">
+									{#each JSON.parse(agent.tool_scope_json) as tool}
+										<span class="px-2 py-0.5 bg-bg-primary border border-border rounded text-xs font-mono text-text-primary/90">{tool}</span>
+									{/each}
+								</div>
+							</div>
+						{/if}
+					</div>
+				{/if}
+
+				{#if agent.system_prompt}
+					<div class="pt-3 border-t border-border">
+						<div class="flex items-center justify-between mb-1">
+							<p class="text-xs text-text-secondary uppercase tracking-wide">System Prompt</p>
+							<span class="text-[10px] text-text-secondary">{agent.system_prompt.length} chars</span>
+						</div>
+						<pre class="text-xs bg-bg-primary p-3 rounded-lg border border-border font-mono text-text-primary/90 whitespace-pre-wrap break-words max-h-96 overflow-y-auto">{agent.system_prompt}</pre>
+					</div>
+				{/if}
 			</div>
 
 			<!-- Actions -->