diff --git a/BURNIN.md b/BURNIN.md
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+++ b/BURNIN.md
@@ -2848,3 +2848,102 @@ unchanged.
   "ready_for_verification"}`. It is the whole lever for this rung.
 - Ingest turns every issue label into a required capability, so a rig issue
   must carry no labels or it will not schedule.
+
+## Run 20, 2026-08-29: the mismatch and replan ladder, and three defects
+
+Task `06G4WJ9T4F35NZC4Z8QQXM9Z6G` (issue 29) on `de18f37`, plus a first attempt
+on `06G4WDJ06G7FK00QF73Z9DDBT4` (issue 27) on `c587f2c` that found F65.
+
+The lever throughout is the agent's own file, written by the operator with the
+worker stopped: `.orchestra/plan-mismatch.json`, carrying `phase_id`,
+`observed`, `contradicts`, `evidence` and `requested_action`. The worker fills
+`plan_ref` and `at_sha` from what it can verify, never from the file.
+
+### F65: a task that stops for a human never stopped
+
+Found on the first attempt, live:
+
+```text
+16:04:25  PlanMismatchRecorded  phase-2  human_decision
+16:04:25  worker: plan mismatch refused: task version conflict
+16:04:48  PlanPhaseVerified phase-1     work continues as if nothing happened
+```
+
+`Store.Append` fences every lifecycle event on a leased task against the
+current owner and epoch. `blockForPlanMismatch` carried neither `harness_id`
+nor `lease_epoch`, so the block was refused on every task that was actually
+running, which is every task that can produce a mismatch. The observation was
+durable and the transition silently did not happen: the repo's own documented
+failure shape. `raiseTrajectoryGate` had the identical omission, so the
+trajectory gate could never have stopped a live task either.
+
+`RecordPlanMismatch` also returns that error after the record is already
+appended, so the worker told the agent its report was refused for a report
+Orchestra had accepted.
+
+Fixed in `de18f37` with one `fenceToLease` helper, called by all three stops.
+The human-decision path already did it correctly and explained why in a
+comment; that comment is now the helper.
+
+**Why no test caught it.** `planWith` never leased its task, so every
+plan-progress and plan-mismatch test ran in a state no agent can be in. The
+`lease` helper in the same package carries a comment warning about exactly
+that. It leases now, and the mismatch block test fails without the fence with
+the same `task version conflict`.
+
+### Proven: human_decision stops, and the reply resumes the same plan
+
+```text
+16:24:21  PlanMismatchRecorded  phase-2  human_decision
+16:24:21  TaskBlocked           plan_mismatch, lifecycle awaiting_human
+18:24:46  HumanDecisionRecorded operator_instruction   (Gitea's timestamp)
+16:25:16  TaskCorrected         resumed
+16:25:16  TaskLeased            plan_ref unchanged at 0bc8ef84
+16:25:21  TaskPickupValidated
+```
+
+55 seconds from block to resumed, on the same plan, with no reseal. The
+blocker packet states the observation, the plan's claim and the evidence.
+
+This is also the live proof of F64: before `6cb2f93` nothing read a blocked
+task's comments, because the reconciler ran only before a lease and at a turn
+boundary, and a blocked task is never leased.
+
+### Proven: replan keeps the old plan until a replacement seals
+
+```text
+16:26:07  PlanMismatchRecorded  phase-3  replan
+16:26:07  WorkPhaseChanged      plan     reopen=PlanMismatchRecorded
+          during planning: plan_ref 0bc8ef84 accepted, phase-1 and phase-2 counted
+          after the seal:
+            plan_ref     922f293b
+            plan_history [0bc8ef84]
+            progress     empty
+          successor in implement: four phases, all "not started"
+```
+
+The successor's launch context carries the replacement whole, with files,
+changes and verification per phase. The old progress stops counting because
+`PlanPhases()` drops records whose plan ref is not the accepted one. An
+abandoned replan would have cost nothing.
+
+### F66: the planner replans blind
+
+The planning session convened by a replan is given the ordinary plan brief and
+an empty template. Its launch context says nothing about the plan that already
+exists, the contradiction that reopened the phase, the phase id, the evidence,
+or the fact that its output supersedes an accepted plan. The only human input
+it carried was an unrelated earlier correction.
+
+Everything it needs is already durable. `PlanMismatchRecorded` holds the phase,
+the observation, the contradiction and the evidence, and `reopenPhase` writes
+`reopen_phase_id` onto the `WorkPhaseChanged` payload. None of it reaches the
+agent, so nothing stops the replacement from sealing with the same
+contradiction in it.
+
+### Smaller observation
+
+The implement session kept working after the reopen. It verified phase-2
+against the old plan 40 seconds after the task had moved to `plan`. Harmless,
+because supersession discards it, but the reopen does not end the session that
+reported the contradiction. That session rotates at its own next boundary.