Adopt an already-published PR instead of publishing again

Fixes counterexample 5 from specs/orchestrator.qnt. A crash after the
PR was opened but before PR_OPEN was recorded left the agent in
EXECUTING; the restart question's 'continue' and 'start' then published
again, Gitea refused a second PR, and there was no way back to PR_OPEN.
On the live run the executor model happened to notice the existing
work; recovery must not depend on that.

- Boot (A3 step 4): in EXECUTING, if Gitea shows the milestone's PR
  open, adopt it, watch it from the start, and resume in PR_OPEN with a
  notice. Gitea unreachable or the PR closed: the restart question, as
  before.
- MilestonePublisher.publish is idempotent: after pushing, an open PR
  for the branch is adopted (and so updated) rather than a second one
  opened. This also covers a PR opened whose response was lost.
- The model adopts too, gains the lost-response outcome, and now counts
  PRs opened per milestone (one_pr_per_milestone was a flag the fixed
  model could never set). A mutant without adoption fails the new
  scenario; the properties held over 200,000 traces each.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

specs/orchestrator.qnt

@@ -67,6 +67,7 @@ module orchestrator {
     prThread: List[PrComment],
     nextId: int,
     giteaPr: int -> str,      // PR key -> "open" / "closed"
+    opened: int -> int,       // PR key -> how many PRs Gitea ever opened for it
     openIssues: Set[int],     // plan issues still open, by task
     // -- volatile: lost in a crash --
     queue: List[Job],
@@ -83,7 +84,6 @@ module orchestrator {
     answered: Set[int],       // ... and answered (pushed, asked, or reported)
     badApproval: bool,
     staleFeedback: bool,
-    dupPublish: bool,
   }
 
   // ---- helpers ------------------------------------------------------------
@@ -97,6 +97,11 @@ module orchestrator {
   pure def prIds(s: Sys, key: int): int =
     s.prThread.foldl(0, (acc, c) => if (c.key == key and c.id > acc) c.id else acc)
   pure def max(a: int, b: int): int = if (a > b) a else b
+  // Gitea opens a PR for a branch.
+  pure def openPr(s: Sys, key: int): Sys =
+    { ...s, giteaPr: s.giteaPr.put(key, "open"),
+      opened: s.opened.put(key, (if (s.opened.keys().contains(key)) s.opened.get(key) else 0) + 1) }
+
   pure def queued(s: Sys, src: str): bool = s.queue.foldl(false, (acc, j) => acc or j.src == src)
 
   // _await_input
@@ -260,6 +265,11 @@ module orchestrator {
       awaitInput(s0, { kind: "boot", g: "", interrupted: s.st })
     else if (s.st == "AWAIT_INPUT" and s.pending.kind != "")
       s0
+    else if (s.st == "EXECUTING" and giteaUp and prState(s, prKeyOf(s)) == "open")
+      // A3 step 4: the milestone's PR is open, so it was published and only
+      // PR_OPEN went unrecorded. Adopt it; nothing watched it, so from 0.
+      { ...s0, st: "PR_OPEN", prOn: true, prKey: prKeyOf(s), prLast: 0,
+        prWatch: { on: true, floor: 0 }, planWatch: OFF }
     else if (s.st == "PR_OPEN")
       { ...s0, prWatch: if (s.prOn) { on: true, floor: s.prLast } else OFF }
     else if (s.st == "IDLE" or (SIGNOFF.contains(s.st) and s.gate.on))
@@ -278,11 +288,11 @@ module orchestrator {
     boardOn: false, boardPosted: false, boardLast: 0,
     intents: Set(),
     planThread: List(), prThread: List(), nextId: 1,
-    giteaPr: Map(), openIssues: Set(),
+    giteaPr: Map(), opened: Map(), openIssues: Set(),
     queue: List(), work: "none", workGate: "", workCid: 0, pubStage: 0, cancel: false,
     planWatch: OFF, prWatch: OFF,
     shown: NO_PLAN, taken: Set(), answered: Set(),
-    badApproval: false, staleFeedback: false, dupPublish: false,
+    badApproval: false, staleFeedback: false,
   }
 
   // Each action has a deterministic form taking its choices as parameters,
@@ -372,8 +382,9 @@ module orchestrator {
 
   // Publishing, one step at a time, so a crash can land between them
   // (MilestonePublisher.publish and control._publish_milestone):
-  // 0 commit, begin_intent; 1 push, open the PR; 2 commit_intent;
-  // 3 record the PR, watch it, PR_OPEN.
+  // 0 commit, begin_intent; 1 push, then adopt an open PR for the branch or
+  // open one ("lost": Gitea opened it but the response never came back);
+  // 2 commit_intent; 3 record the PR, watch it, PR_OPEN.
   action publishStep(outcome: str): bool = {
     val key = prKeyOf(s)
     all {
@@ -389,10 +400,11 @@ module orchestrator {
           else if (outcome == "fail" or outcome == "nochanges")
             awaitInput(endWork(s), { kind: "milestone_stopped", g: "", interrupted: "" })
           else if (prState(s, key) == "open")
-            // Gitea refuses a second PR for the branch: a GiteaError.
-            awaitInput(endWork({ ...s, dupPublish: true }),
+            { ...s, pubStage: 2 }  // adopted, never a second
+          else if (outcome == "lost")
+            awaitInput(endWork(openPr(s, key)),
                        { kind: "milestone_stopped", g: "", interrupted: "" })
-          else { ...s, giteaPr: s.giteaPr.put(key, "open"), pubStage: 2 }
+          else { ...openPr(s, key), pubStage: 2 }
         else if (s.pubStage == 2)
           { ...s, intents: s.intents.exclude(Set(key)), pubStage: 3 }
         else
@@ -423,7 +435,7 @@ module orchestrator {
     nondet up = Set(true, false).oneOf()
     nondet planOutcome = Set("submit", "ask", "error", "stopped", "exception").oneOf()
     nondet workOutcome = Set("completed", "stopped", "escalate", "exception").oneOf()
-    nondet pubOutcome = Set("ok", "nochanges", "fail", "exception").oneOf()
+    nondet pubOutcome = Set("ok", "nochanges", "fail", "lost", "exception").oneOf()
     any {
       send(kind), commentPlan(ckind), commentPr, pollPlan, pollPr, runJob(up),
       finishPlanning(planOutcome, up), finishExec(workOutcome), publishStep(pubOutcome),
@@ -449,8 +461,8 @@ module orchestrator {
   // Rejection feedback only ever lands on the plan it was written about.
   val feedback_only_on_what_was_seen = not(s.staleFeedback)
 
-  // Never a second attempt to open a PR for a milestone that has one.
-  val one_pr_per_milestone = not(s.dupPublish)
+  // Never more than one PR opened for a milestone.
+  val one_pr_per_milestone = s.opened.keys().forall(k => s.opened.get(k) <= 1)
 
   // A review comment the agent took up is answered, or is being worked on.
   val review_comments_answered =

specs/orchestrator_scenarios.qnt

@@ -1,7 +1,8 @@
 // Counterexamples found in orchestrator.qnt, written out as short traces.
 // Each ends by expecting the property it breaks to be false; once the design
 // is fixed, the expectation is flipped and the trace kept as a regression.
-// Fixed: 1-4 (replies bind to the revision up when they arrived).
+// Fixed: 1-4 (replies bind to the revision up when they arrived), 5 (boot
+// and publishing adopt an open PR).
 //
 // Run:  quint test specs/orchestrator_scenarios.qnt   (runs every *Test)
 module orchestrator_scenarios {
@@ -77,22 +78,32 @@ module orchestrator_scenarios {
       .expect(s.st == "AWAIT_MILESTONE_SIGNOFF" and feedback_only_on_what_was_seen)
 
   // 5. A crash after the PR is opened but before PR_OPEN is recorded.
-  //    Boot finds the intent's PR and marks it done, but the state still
-  //    says EXECUTING, so it asks the restart question. 'continue' returns
-  //    to the approved plan, and starting it publishes again: Gitea refuses
-  //    a second PR for the branch, and there is no path back to PR_OPEN.
+  //    Boot found the intent's PR and marked it done, but the state still
+  //    said EXECUTING, so it asked the restart question; 'continue' and
+  //    'start' then published again, which Gitea refused, with no path back
+  //    to PR_OPEN. Fixed: boot sees the open PR and adopts it.
   run crashAfterOpeningThePrPublishesAgainTest =
     toMilestoneApproved
       .then(send("start")).then(runJob(true))
       .then(finishExec("completed"))
       .then(publishStep("ok"))   // begin_intent
       .then(publishStep("ok"))   // push, open the PR
-      .then(crash(true))         // intent verified and committed; state EXECUTING
-      .then(send("continue")).then(runJob(true))
+      .then(crash(true))         // adopted on boot
+      .expect(s.st == "PR_OPEN" and s.prOn and one_pr_per_milestone)
+
+  // 5b. Gitea opens the PR but the response is lost; the operator starts
+  //     the milestone again. Publishing adopts the open PR.
+  run lostResponseThenRetryAdoptsThePrTest =
+    toMilestoneApproved
+      .then(send("start")).then(runJob(true))
+      .then(finishExec("completed"))
+      .then(publishStep("ok")).then(publishStep("lost"))
+      .then(send("continue")).then(runJob(true))   // back to the approved plan
       .then(send("start")).then(runJob(true))
       .then(finishExec("completed"))
       .then(publishStep("ok")).then(publishStep("ok"))
-      .expect(s.st == "AWAIT_INPUT" and not(one_pr_per_milestone))
+      .then(publishStep("ok")).then(publishStep("ok"))
+      .expect(s.st == "PR_OPEN" and one_pr_per_milestone)
 
   // 6. A crash while the executor answers a review comment. The comment's
   //    cursor was saved before the work started (at most once), and a