michaelfutol · michaelfutol · Jul 14, 2026 · Jul 14, 2026 · Jul 14, 2026
diff --git a/README.md b/README.md
@@ -14,7 +14,7 @@ FutolStructure is a browser-based structural engineering workbench for reinforce
   <a href="SECURITY.md">Security</a>
 </p>
 
-[![Build](https://img.shields.io/badge/build-v3.16.117-2563eb)](https://futolstructure.vercel.app)
+[![Build](https://img.shields.io/badge/build-v3.16.118-2563eb)](https://futolstructure.vercel.app)
 [![Validation](https://github.com/michaelfutol/futolstructure/actions/workflows/validate.yml/badge.svg)](https://github.com/michaelfutol/futolstructure/actions/workflows/validate.yml)
 ![Platform](https://img.shields.io/badge/platform-browser-0f766e)
 ![Maturity](https://img.shields.io/badge/maturity-technical%20preview-f59e0b)
@@ -53,7 +53,7 @@ flowchart LR
 - Tributary area and gravity load distribution from slabs to beams, columns, footings, and base reactions.
 - Plan drafting aids including coordinated member tags, grid bubbles, dimensions, ortho measurement, snapping, and lock indicators.
 - 3D review with display schemes, member colors and opacity controls, foundation geometry, slab transparency, and stair geometry.
-- `.fstr` project save/load with guarded autosave, recovery diagnostics, floor deletion warnings, and persisted member locks.
+- `.fstr` project save/load with guarded autosave, immutable pre-overwrite revisions, destructive-change review, recovery diagnostics, floor deletion warnings, and persisted member locks.
 - Stair Builder geometry with destination slab openings, DXF footprint output, and 3D review.
 - Reports and schedules for columns, beams, slabs, footings/base reactions, and preliminary design summaries.
 - Coordinated multi-floor DXF drawing packages, IFC2x3, STAAD.Pro, ETABS 22 OAPI, and ETABS-to-SAFE handoff paths.
@@ -99,7 +99,7 @@ python -m pip install -r v3/tools/requirements-dxf.txt
 node v3/tools/check-fs.js
 ```
 
-The browser smoke covers initialization, plan geometry, slab ownership, cantilever behavior, persistence and recovery guards, member locking, measurement tools, stair persistence, 3D rendering, coordinated DXF completeness, strict DXF open/audit/save/reopen validation, and export payload parity.
+The browser smoke covers initialization, plan geometry, slab ownership, cantilever behavior, persistence and recovery guards, protected-revision restore/download, the 50-revision retention limit, historical `.fstr` migration, member locking, measurement tools, stair persistence, 3D rendering, coordinated DXF completeness, strict DXF open/audit/save/reopen validation, and export payload parity.
 
 Where AutoCAD 2025 is installed, run the native read gate against a generated package without modifying it:
 
@@ -116,6 +116,7 @@ futolstructure/
 |-- v3/
 |   |-- assets/           Product identity and screenshots
 |   |-- engine/           Extracted structural calculation helpers
+|   |-- persistence/      Protected project revision storage
 |   |-- tools/            Regression smoke runner
 |   `-- index.html        Current application
 |-- index.html            Hosted root entry

diff --git a/docs/FS-118_RELEASE_NOTES.md b/docs/FS-118_RELEASE_NOTES.md
@@ -0,0 +1,45 @@
+# FS-118 Protected Project Revisions
+
+- **Release:** FutolStructure v3.16.118
+- **Build:** FS-118
+- **Date:** 2026-07-14
+
+## Purpose
+
+FS-118 protects user-authored structural intent before an existing `.fstr` file is overwritten. It builds on the production FS-117 R12 DXF baseline without changing the DXF envelope, structural analysis formulas, solver exporters, or active-model geometry rules.
+
+## Included
+
+- Immutable IndexedDB revision records containing a cloned project payload, source identity, schema/build provenance, structural summary, health assessment, and model delta.
+- Automatic pre-overwrite capture for browser file-handle saves.
+- A guarded save review when floors, members, locks, offsets, cantilevers, or corner slabs are removed, or when void/deletion counts increase.
+- A health gate that quarantines implausible autosaves and can restore the last known healthy browser snapshot.
+- Recovery UI for revision history, restore, and `.fstr` download.
+- Per-project retention of the newest 50 protected revisions.
+- Project and source-revision identity embedded in new `.fstr` saves and report provenance.
+- A legacy v2.8 two-floor fixture proving hidden geometry, member locks, and beam offsets survive migration and repeated round trips.
+
+## Storage Boundary
+
+Protected revisions are local to the browser profile and device through IndexedDB. They are not cloud backups and do not replace dated external `.fstr` files. Clearing site data or using another browser/profile removes access to that local revision history.
+
+## Acceptance Gates
+
+- Inline and external JavaScript syntax checks.
+- Full Chrome/Edge browser regression.
+- Pre-overwrite capture, destructive-delta detection, invalid-health blocking, restore, and revision download.
+- Exact retention of revisions 5 through 54 after 55 ordered writes, proving a 50-record cap.
+- Legacy v2.8 `.fstr` load, migration, and two successive round trips.
+- Current Olango three-floor project smoke.
+- Unchanged FS-117 strict AutoCAD R12 parser round trip and native AutoCAD read gate.
+
+## Excluded
+
+- Cloud synchronization, user accounts, shared project history, and server-side backup.
+- Historical helper scripts and unrelated workspace edits.
+- Structural solver, stair, IFC, STAAD, ETABS, SAFE, or broad UI changes.
+- Changes to the FS-117 DXF R12 writer.
+
+## Rollback
+
+If FS-118 fails in production, revert only the FS-118 merge commit. FS-117 remains the known-good DXF production baseline.
diff --git a/docs/RELEASE_HYGIENE.md b/docs/RELEASE_HYGIENE.md
@@ -20,6 +20,7 @@ Use this checklist before pushing a public FutolStructure update.
 - `v3/assets/futolstructure-icon.png`
 - `v3/assets/screenshots/`
 - `v3/engine/`
+- `v3/persistence/`
 - `v3/dxf-export.js`
 - `v3/tools/check-fs.js`
 - `v3/tools/check-dxf-autocad.ps1`
@@ -43,6 +44,8 @@ python -m pip install -r v3/tools/requirements-dxf.txt
 node v3/tools/check-fs.js
 ```
 
+For persistence releases, the browser gate must also prove pre-overwrite capture, destructive-delta review, health blocking, restore/download behavior, exact 50-revision retention, and legacy `.fstr` round-trip compatibility.
+
 For a DXF release on a workstation with AutoCAD 2025:
 
 ```powershell

diff --git a/v3/dxf-export.js b/v3/dxf-export.js
@@ -724,7 +724,7 @@
         stackY = indexTable.bottomY - 1;
 
         const modelRows = [
-            { item: 'Build', value: DXF_PACKAGE_BUILD },
+            { item: 'Build', value: `${audit.build} / DXF ${audit.writerBuild}` },
             { item: 'FSTR schema', value: window.getProjectProvenance?.().fstrSchemaVersion || 'unknown' },
             { item: 'Source revision', value: window.getProjectProvenance?.().sourceRevisionId || 'unsaved working state' },
             { item: 'Floors', value: state.floors?.length || 0 },
@@ -848,8 +848,10 @@
         const floorGeometryById = collect3DFloorGeometry();
         const planBounds = calculatePlanBounds(floorGeometryById);
         const writer = new DxfWriter();
+        const releaseBuild = window.getReleaseManifest?.().buildId || DXF_PACKAGE_BUILD;
         const audit = {
-            build: DXF_PACKAGE_BUILD,
+            build: releaseBuild,
+            writerBuild: DXF_PACKAGE_BUILD,
             layerSource: 'FT_LayerMap.xlsx structural mapping embedded in FutolStructure',
             floorIds: state.floors.map(floor => floor.id),
             plans: { layouts: 0, tributary: 0, foundation: 0 },
@@ -861,7 +863,7 @@
         const cellHeight = planBounds.height + 5.2;
         const packageTop = 0;
         writer.text(0, packageTop + 4.1, 'FUTOLSTRUCTURE - COORDINATED DXF DRAWING PACKAGE', DXF_LAYER.TEXT, 0.48);
-        writer.text(0, packageTop + 3.45, `${DXF_PACKAGE_BUILD} | UNITS: METERS | GENERATED ${localDateStamp()}`, DXF_LAYER.TEXT, 0.2);
+        writer.text(0, packageTop + 3.45, `${releaseBuild} | DXF WRITER ${DXF_PACKAGE_BUILD} | UNITS: METERS | GENERATED ${localDateStamp()}`, DXF_LAYER.TEXT, 0.2);
         writer.text(0, packageTop + 3.05, 'Plans, schedules, load summary, and preliminary BOQ use FT structural layer mapping.', DXF_LAYER.TEXT, 0.18);
 
         (state.floors || []).forEach((floor, rowIndex) => {