feat(nomos): retry cap, vm: targets, inspect_path, goal supersession, runbooks

Session-review implementation for the three sessions audited in
plans/2026-07-18-session-review-three-sessions.md. v0.7.11 → v0.7.12.

P0.1 — retry cap + investigate-before-retry (cmd/nomos/retrycap.go,
agent.go): after 3 identical failing run calls in a single turn, refuse
to dispatch the call again and return a directive to investigate *why*
(ps/strace/lsof) or surface the blocker. Per-turn scope so a fresh turn
after the operator responds can retry once more. Session 1e9c7691's 20+
identical chown retries (knfsd held a kernel lock on the exported NFS
dir) is the direct motivation.

P0.2 + P1.8 + P2.10 — SOUL.md guidance: hung command is not a failed
command (investigate before retry); ask before proposing a multi-step
migration; multi-goal sessions summarize the arc not just the last goal.

P1.3 — two new runbook entities in seeds/knowledge.yaml:
  - nfs-exported-dir-mutation-hang (the knfsd fchownat lock procedure:
    killall → exportfs -u → mutate → exportfs -a → verify)
  - netbird-mgmt-oidc-race-after-upgrade (docker restart netbird-mgmt
    after ~30s for the traefik/authentik OIDC race)

P1.4 — setGoal emits task.superseded event when prior goal is overwritten
by a different goal (store.go, TestSetGoal_SupersededEvent). Session
55927f0a had two set_goal calls with the first silently abandoned.

P1.5 — inspect_path MCP tool: runs mount/df/ls/stat for one path across
up to 8 targets in one parallel call, replacing the 15+ run-call
fact-gathering fan-out sessions 1 and 2 each spent on cross-target path
tracing (tools.go, server.go: inspectPathAcrossTargets, inspectOneTarget).

P1.6 — vm: target support in run via qm guest exec (no more SSH-hop
with nested quoting). Extracted shared resolveProxmoxHostSlug for
LXC + VM, with hosts-relationship fallback when attributes.host is
absent (server.go, tools.go). Session 55927f0a's SSH-hop workarounds
for vm:zimaos are the direct motivation.

Deferred (documented in plan): P1.7 (approval window auto-extend on
timeout) and P2.9 (long-running command PENDING detection) — both
addressed at lower cost by the retry cap. Session 3's poll-after-timeout
pattern already works; the cap protects against the failure mode.

cmd/nomos/agent.go

@@ -168,10 +168,10 @@ type toolDef struct {
 }
 
 type agentEvent struct {
-	Type       string `json:"type"`
-	Data       any    `json:"data,omitempty"`
-	SessionID  string `json:"session_id,omitempty"`
-	Iteration  int    `json:"iteration,omitempty"`
+	Type      string `json:"type"`
+	Data      any    `json:"data,omitempty"`
+	SessionID string `json:"session_id,omitempty"`
+	Iteration int    `json:"iteration,omitempty"`
 }
 
 func (a *agent) chat(ctx context.Context, sessionID, message string, emit func(agentEvent)) {
@@ -349,6 +349,15 @@ func (a *agent) chatWith(ctx context.Context, sessionID, message, systemInject s
 		messages = append(messages, openai.SystemMessage(systemInject))
 	}
 
+	// Retry cap (P0.1 from plans/2026-07-18-session-review-three-sessions.md):
+	// track failing `run` calls within this turn so an identical command that
+	// keeps failing is refused after maxRunRetries attempts. Without this,
+	// session 1e9c7691 retried the same `chown` ~20 times, each retry piling
+	// up a zombie process on the target (knfsd was holding a kernel lock).
+	// The tracker is per-turn — a fresh turn after the operator responds can
+	// retry once more, so this doesn't permanently block recovery.
+	retries := newRunRetryTracker()
+
 	for i := 0; i < maxIterations; i++ {
 		params := openai.ChatCompletionNewParams{
 			Model:    openai.ChatModel(a.model),
@@ -467,6 +476,33 @@ func (a *agent) chatWith(ctx context.Context, sessionID, message, systemInject s
 				sawCompleteTask = true
 			}
 
+			// Retry cap: if this `run` call has already failed
+			// maxRunRetries times this turn with the same (target,
+			// command), refuse to dispatch it again. Return a synthetic
+			// tool result directing the agent to investigate *why* the
+			// command hangs instead of retrying. See retrycap.go and
+			// plans/2026-07-18-session-review-three-sessions.md P0.1.
+			if tc.Function.Name == "run" {
+				t, _ := args["target"].(string)
+				c, _ := args["command"].(string)
+				key := runFailureKey(t, c)
+				if n := retries.failures(key); n >= maxRunRetries {
+					directive := runRetryDirective(t, c, n)
+					slog.Warn("nomos: run retry cap hit — refusing dispatch",
+						"target", t, "failures", n, "session", sessionID)
+					a.store.logActivity(ctx, a.agentID, sessionID, tc.Function.Name, args,
+						tc.Function.Arguments, directive, 0, false, correlationID)
+					emit(agentEvent{
+						Type:      "tool_result",
+						Data:      map[string]any{"name": tc.Function.Name, "result": directive, "id": tc.ID, "retry_capped": true},
+						SessionID: sessionID,
+						Iteration: i + 1,
+					})
+					messages = append(messages, openai.ToolMessage(directive, tc.ID))
+					continue
+				}
+			}
+
 			emit(agentEvent{
 				Type:      "tool_use",
 				Data:      map[string]any{"name": tc.Function.Name, "args": args, "id": tc.ID},
@@ -508,6 +544,22 @@ func (a *agent) chatWith(ctx context.Context, sessionID, message, systemInject s
 			if callErr != nil {
 				a.store.logActivity(ctx, a.agentID, sessionID, tc.Function.Name, args, inputStr, callErr.Error(), elapsed, false, correlationID)
 
+				// Retry cap: dispatch errors (e.g. MCP client timeout)
+				// count toward the cap too. A command that keeps timing
+				// out at the gateway is exactly the pattern we want to
+				// break — see session 1e9c7691's 20+ identical
+				// `chown` timeouts.
+				if tc.Function.Name == "run" {
+					t, _ := args["target"].(string)
+					c, _ := args["command"].(string)
+					key := runFailureKey(t, c)
+					n := retries.recordFailure(key)
+					if n >= maxRunRetries {
+						slog.Warn("nomos: run failure cap reached — next identical call will be refused",
+							"target", t, "failures", n, "session", sessionID)
+					}
+				}
+
 				emit(agentEvent{
 					Type:      "tool_result",
 					Data:      map[string]any{"name": tc.Function.Name, "error": callErr.Error(), "id": tc.ID},
@@ -551,6 +603,25 @@ func (a *agent) chatWith(ctx context.Context, sessionID, message, systemInject s
 			messages = append(messages, openai.ToolMessage(string(resultJSON), tc.ID))
 			slog.Info("nomos: tool success", "tool", tc.Function.Name, "ms", elapsed)
 
+			// Retry cap: record failures of `run` calls so the cap above
+			// can refuse a repeated identical failure. A "failure" here
+			// means the dispatch errored OR the MCP result text matches
+			// the "run on <target>: ERROR …" signature — both indicate
+			// the command actually ran and failed, not just that it
+			// queued for approval (pending approvals are not failures).
+			// Pass the RAW result text (not JSON-encoded) so the helper's
+			// HasPrefix check sees "run on …" not "\"run on …\"".
+			if isRunFailure(tc.Function.Name, runResultText(result), callErr) {
+				t, _ := args["target"].(string)
+				c, _ := args["command"].(string)
+				key := runFailureKey(t, c)
+				n := retries.recordFailure(key)
+				if n >= maxRunRetries {
+					slog.Warn("nomos: run failure cap reached — next identical call will be refused",
+						"target", t, "failures", n, "session", sessionID)
+				}
+			}
+
 			// ask_operator pauses the task: the agent has posed a decision only
 			// the operator can make. End the turn here so it doesn't barrel past
 			// its own question — the answer (panel or chat reply) resumes it.