Native Visio COM gate, 2026-10-03

Exact decoded-length text safety in 0.10.1

An additional native-generated fixture exposed an admitted 0.10.0 text edit that Visio rejected: Hello\n\n to Jello\n\n. The old encoded-fit strategy could add decoded zero suffix bytes. 0.10.1 preserves both the original encoded allocation and exact decoded block length, using bounded token variations. Edits without a safe exact fit refuse atomically.

Five production text cases pass fresh Visio open, native save and reopen, with only the captured target text changed. This includes Jello/World/Again/Hallo in the new literal fixture and World in the original three-shape fixture. The new Jello artifact SHA256 is 7cbe62c046c62662dda6edb17dc56828b3eb575060ff9868952b083dce52c832; the original fixture's current World artifact is 1d8d6d2c214490d4676adc758e4b1e8a0d383449d2cdb146e9bec47c829050bc. No-op bytes are exact; repeated model edits reproduce the natively tested Again artifact. Run node scripts/prepare-native-vsd-text-safety-edits.mjs after building to reproduce candidates and record module/artifact hashes. Generation does not itself validate Visio. See the full native evidence and limits.

Native transform editing, rendering, nonempty masters/layers and general ShapeSheet evaluation remain unverified or unsupported.

Historical bounded text writing in 0.10.0

The production text writer now compresses eligible edits into the original leaf allocation, preserving all page/table offsets. The owned native fixture's Hello\n\n to World\n\n output SHA256 is cc257f441f2d30fb30ea9b0281fcf4570c092532518a4894a28fee4ae9bf3bdb. Visio 16 opens it and its native save/reopen; the captured target text changes from Hello\n to World\n and all other captured fields stay unchanged. This is positive evidence for that text case. Native transform editing and rendering remain separate unverified work.

With an explicit trusted 0.10.0 built module, node scripts/prepare-native-vsd-text-edits.mjs C:/trusted-ole2-0.10.0/dist/index.js reproduces the historical output and records module hashes. Run native-visio-snapshot.ps1 against the original and output, using an explicit target-text delta; the generation driver itself does not launch or validate Visio. Capacity, field, overlap and resource-budget refusals preserve bytes and state.

Historical corruption and containment

Microsoft Visio 16.0.20430.20140, AMD64 accepted the repository-owned test/fixtures/vsd/native-visio16-v11.vsd. The fixture SHA256 is c6c97822e7bb2cc3e96da9d7d35fe74ac16a7f2c90d19ad4c80967d2896e0974. It contains one 8×11-inch page, three shapes (rectangle, one-dimensional line, Unicode label ending in U+03A9), six styles, zero masters, and zero layers. Its generator starts with a blank document and sets neutral fixture metadata.

The published 0.9.0 codec produced a corrupt file when shape 1 stored text changed from Hello\n\n to World\n\n. Visio rejected output SHA256 17da1ec00dc7a62bf1d4e84b8d43bc7729935b6b12b4986094f0fa99b14e2677 with HRESULT -2032466840. This failed native result remains part of the evidence.

The reviewed containment fix 6eff0b937048c85b852706edb3568fde8bd0329b refuses that operation with unsafe-block-relocation. Both its no-op setter and refused-edit serialization retain the original bytes, text, revision 0, and clean state. Fresh Visio instances accepted both serialized files. Their full captured snapshots matched the baseline: page dimensions/scale, IDs/names/text, cell formulas and results, geometry row types/cells, child and connection counts, master/layer arrays, and style count. Native baseline SaveAsEx/reopen also preserved those captures. Refusal is not successful writing.

The independent local report records 19 cases, eight accepted native controls, 11 native rejections, and 22 named passing assertions. Three safe root/size relocation controls preserved the whole native snapshot; page/page-table relocation controls failed even without semantic changes. The old handcrafted fixture and its edits were rejected as an unrecognized version (-2032466854), despite earlier independent libvisio acceptance.

This is the historical 0.9.1 containment gate. Current bounded-compression text writes admit the tested World edit; this refusal driver requires the explicit trusted 0.9.1 build, rather than the current dist:

node scripts/prepare-native-vsd-refusal.mjs C:/trusted-ole2-0.9.1/dist/index.js
pwsh -NoProfile -File scripts/native-visio-snapshot.ps1 -InputPath .native-validation/native-visio/native-noop.vsd -OutputPath .native-validation/native-visio/noop.json
pwsh -NoProfile -File scripts/native-visio-snapshot.ps1 -InputPath .native-validation/native-visio/native-refused.vsd -OutputPath .native-validation/native-visio/refused.json

The 0.9.1 release integrates that containment fix at 7592548eeb05b7e1577531400cade63e2a2fad7e. It requires each encoded leaf to fit its original allocation exactly and does not relocate page or ancestor blocks.

The driver can take an explicit trusted built index.js path and output directory as its first two arguments. Its manifest records exact module and artifact hashes. Generate fresh original content with test/fixtures/vsd/generate-native-fixture.ps1; Office timestamps may vary. The harness uses a new Visio.InvisibleApp, events disabled, and OpenEx flags 458 (read-only, hidden, no MRU, macros disabled, no workspace). EventsEnabled set to false also prevents RUNADDON execution during formula evaluation. Each case has a 45-second bound; cleanup uses only the owned HWND-derived Windows PID, start time, and executable proof. All 19 recorded owned processes exited.

Limits: the stored model includes a terminal paragraph LF omitted by COM Text. The binary version is 11; COM Document.Version returns 983040 on reopen and 720896 immediately after the explicit legacy save setting. The line transform writer refuses missing-or-formula-transform. Zero masters/layers provide no positive coverage for those features. No visual/render fidelity, evaluated styles/formulas/masters, arbitrary geometry editing, or full VSD parity is claimed.