fix(run): the FinalGuard nudge round can never replace a non-blank answer

Live regression (mort run d5ec39f4, 2026-07-15): a research run's page-cache
file false-positived the guard, and the nudge round's meta closer ("my
answer above stands as-is") REPLACED the real answer — hosts deliver
Output text plus separately-drained attachments, so the user received the
closer and never saw the answer.

New merge policy: the nudge round exists to make tool calls (queue the
delivery); its final text is discarded and recorded as a final_nudge_result
audit event, so a round that declined to queue stays observable without
reaching the user. The only exception is a blank original stop turn, where
the nudge round's text is the only answer there is. Messages/Usage still
merge (audit, PostRun, checkpoint continuity).

Additive on top of 007b753 (mort main pins that commit as a pseudo-version;
this branch must never be rewritten).

Co-Authored-By: Claude Fable 5 <[email protected]>

run/executor.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"strings"
 	"time"
 
 	"gitea.stevedudenhoeffer.com/steve/majordomo/agent"
@@ -500,6 +501,15 @@ func (e *Executor) Run(ctx context.Context, ra RunnableAgent, inv tool.Invocatio
 		// small fixed step cap so a misread nudge can't start a new work spree.
 		// The nudge round's failure is non-fatal — the original successful result
 		// stands (any attachments it queued before failing still deliver).
+		//
+		// The nudge round's job is to QUEUE deliveries (tool calls); its TEXT is
+		// meta-commentary ("answer above stands", "sent!") that must never replace
+		// the answer the user asked for — hosts deliver Output text + separately
+		// drained attachments, so replacing Output with the nudge round's closer
+		// LOSES the real answer (live regression: run d5ec39f4, a research run's
+		// page-cache false positive whose nudge reply "my answer above stands
+		// as-is" was delivered INSTEAD of the answer). Keep the original Output
+		// unless it was blank; log what was discarded so hosts can audit.
 		if runErr == nil && runRes != nil && e.cfg.Ports.FinalGuard != nil {
 			state := FinalState{
 				Output:        runRes.Output,
@@ -529,7 +539,20 @@ func (e *Executor) Run(ctx context.Context, ra RunnableAgent, inv tool.Invocatio
 					slog.Warn("run: final-nudge round failed; keeping original result",
 						"run_id", inv.RunID, "error", nudgeErr)
 				} else if nudgeRes != nil {
-					runRes.Output = nudgeRes.Output
+					if strings.TrimSpace(runRes.Output) == "" {
+						// Degenerate original (blank stop turn): the nudge round's
+						// text is the only answer there is.
+						runRes.Output = nudgeRes.Output
+					} else if rec != nil {
+						// Discarded meta-text stays observable: a nudge round that
+						// DECLINED to queue while the original claims a send shows
+						// up here, not in the user's reply.
+						rec.LogEvent("final_nudge_result", map[string]any{
+							"discarded_output": nudgeRes.Output,
+						})
+					}
+					// The transcript keeps the nudge round either way (audit,
+					// PostRun, checkpoint continuity).
 					runRes.Messages = nudgeRes.Messages
 				}
 			}