diff --git a/plans/260725-2208-playable-hard-offline/plan.md b/plans/archive/260725-2208-playable-hard-offline/plan.md
similarity index 99%
rename from plans/260725-2208-playable-hard-offline/plan.md
rename to plans/archive/260725-2208-playable-hard-offline/plan.md
index 6775a46..5a4037c 100644
--- a/plans/260725-2208-playable-hard-offline/plan.md
+++ b/plans/archive/260725-2208-playable-hard-offline/plan.md
@@ -19,7 +19,7 @@ All 11 playable levels are degenerate: deleting every guard changes BFS optimal
 moves on every level. Not an authoring problem — four engine defects mean the mechanics never execute.
 CI passed because `levels.solvability.test.js:42-48` asserts only *solvable* and *≤ par*, with no lower bound.
 
-Source reports in `plans/reports/`:
+Source reports in `./reports/` (archived alongside this plan):
 - `puzzle-design-difficulty-audit-260725-2150-level-quality-report.md`
 - `engine-correctness-review-260725-2150-solver-sync-and-state-report.md`
 - `playability-and-ux-audit-260725-2150-player-experience-report.md`
diff --git a/plans/reports/engine-correctness-review-260725-2150-solver-sync-and-state-report.md b/plans/archive/260725-2208-playable-hard-offline/reports/engine-correctness-review-260725-2150-solver-sync-and-state-report.md
similarity index 100%
rename from plans/reports/engine-correctness-review-260725-2150-solver-sync-and-state-report.md
rename to plans/archive/260725-2208-playable-hard-offline/reports/engine-correctness-review-260725-2150-solver-sync-and-state-report.md
diff --git a/plans/reports/from-docs-phase6-to-owner-260726-0012-documentation-and-briefing-accuracy-report.md b/plans/archive/260725-2208-playable-hard-offline/reports/from-docs-phase6-to-owner-260726-0012-documentation-and-briefing-accuracy-report.md
similarity index 100%
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diff --git a/plans/reports/from-engine-phase1-to-level-retune-260725-2208-mechanic-activation-report.md b/plans/archive/260725-2208-playable-hard-offline/reports/from-engine-phase1-to-level-retune-260725-2208-mechanic-activation-report.md
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rename to plans/archive/260725-2208-playable-hard-offline/reports/from-engine-phase1-to-level-retune-260725-2208-mechanic-activation-report.md
diff --git a/plans/reports/from-level-retune-phase3-to-docs-260725-2240-difficulty-harness-and-tuning-report.md b/plans/archive/260725-2208-playable-hard-offline/reports/from-level-retune-phase3-to-docs-260725-2240-difficulty-harness-and-tuning-report.md
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rename to plans/archive/260725-2208-playable-hard-offline/reports/from-level-retune-phase3-to-docs-260725-2240-difficulty-harness-and-tuning-report.md
diff --git a/plans/reports/from-offline-phase5-to-docs-260725-2208-service-worker-and-payload-report.md b/plans/archive/260725-2208-playable-hard-offline/reports/from-offline-phase5-to-docs-260725-2208-service-worker-and-payload-report.md
similarity index 100%
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rename to plans/archive/260725-2208-playable-hard-offline/reports/from-offline-phase5-to-docs-260725-2208-service-worker-and-payload-report.md
diff --git a/plans/reports/from-ux-phase4-to-level-retune-260725-2208-responsive-hints-controls-report.md b/plans/archive/260725-2208-playable-hard-offline/reports/from-ux-phase4-to-level-retune-260725-2208-responsive-hints-controls-report.md
similarity index 100%
rename from plans/reports/from-ux-phase4-to-level-retune-260725-2208-responsive-hints-controls-report.md
rename to plans/archive/260725-2208-playable-hard-offline/reports/from-ux-phase4-to-level-retune-260725-2208-responsive-hints-controls-report.md
diff --git a/plans/reports/offline-and-github-pages-readiness-audit-260725-2150-deploy-report.md b/plans/archive/260725-2208-playable-hard-offline/reports/offline-and-github-pages-readiness-audit-260725-2150-deploy-report.md
similarity index 100%
rename from plans/reports/offline-and-github-pages-readiness-audit-260725-2150-deploy-report.md
rename to plans/archive/260725-2208-playable-hard-offline/reports/offline-and-github-pages-readiness-audit-260725-2150-deploy-report.md
diff --git a/plans/reports/playability-and-ux-audit-260725-2150-player-experience-report.md b/plans/archive/260725-2208-playable-hard-offline/reports/playability-and-ux-audit-260725-2150-player-experience-report.md
similarity index 100%
rename from plans/reports/playability-and-ux-audit-260725-2150-player-experience-report.md
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diff --git a/plans/reports/puzzle-design-difficulty-audit-260725-2150-level-quality-report.md b/plans/archive/260725-2208-playable-hard-offline/reports/puzzle-design-difficulty-audit-260725-2150-level-quality-report.md
similarity index 100%
rename from plans/reports/puzzle-design-difficulty-audit-260725-2150-level-quality-report.md
rename to plans/archive/260725-2208-playable-hard-offline/reports/puzzle-design-difficulty-audit-260725-2150-level-quality-report.md
diff --git a/plans/archive/README.md b/plans/archive/README.md
new file mode 100644
index 0000000..9dcace3
--- /dev/null
+++ b/plans/archive/README.md
@@ -0,0 +1,20 @@
+# Archived plans
+
+Completed work programs. Each directory holds the plan and the reports produced
+while executing it, so the reasoning behind a change stays with the change.
+
+Active plans live one level up in `plans/`; new reports go to `plans/reports/`.
+
+| Plan | Date | Outcome |
+|---|---|---|
+| [260725-2208-playable-hard-offline](260725-2208-playable-hard-offline/plan.md) | 2026-07-25/26 | Made the stealth mechanics actually execute, retuned levels 1–11, added offline play, responsive UI, and a hint system. |
+
+## Why the reports are kept
+
+The audits record measurements that are expensive to reproduce and hard to
+believe without evidence — most importantly that, before this work, deleting
+every guard from every level changed the optimal solution by zero moves, and
+the final playable level could be beaten by walking down the left edge and
+across the bottom. If a future change makes levels feel flat again, the
+ablation numbers in `puzzle-design-difficulty-audit-*` and
+`from-level-retune-phase3-*` are the baseline to compare against.