The Capsule became a file during the project's seventh phase. The repository introduced a versioned package contract for Capsule metadata, original sources, extracted text, a Preparation Brief, and integrity information. Import and export were exposed through native Files, Open-In, share sheet, and AirDrop-compatible system flows.
The user-facing result was one .cato file. Internally, writers and readers kept the logical package structure explicit, checked declared paths and byte counts, and used SHA-256 checksums to detect modification or corruption. Tests covered export and import round trips, missing files, unsafe paths, unsupported versions, tampered payloads, and cleanup after a failed import.
Portability was a product decision as much as a format decision. It created a visible, user-controlled alternative to cloud sync and made the later Mac companion useful.
Checksums establish integrity, not encryption. Exported packages must therefore be handled with the same care as the source material they contain.
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