What this does

Adds @treecrdt/content, a small application-layer codec for storing typed content in TreeCRDT's Uint8Array payloads.

• Plain text uses raw UTF-8 as the canonical representation.
• Images use one versioned binary envelope containing validated MIME metadata, an exact declared byte length, and the original image bytes.
• Recognized but malformed or unsupported envelopes fail closed instead of being interpreted as text.

TreeCRDT core stays media-agnostic. This package is an optional protocol above the byte payload API.

Fast paths

• Text encoding is a direct UTF-8 encode with no envelope, migration, or alternate decoder.
• Unframed bytes decode directly as text.
• Image decoding returns a bounded view of the original bytes instead of copying the image body.

The raw text representation is deliberate, not a backward-compatibility layer: framing text as well would add bytes and another envelope path without improving type discrimination.

Safety

• Parses correctly from non-zero-offset Uint8Array views.
• Validates envelope version, metadata length, declared image length, JSON metadata shape, and an explicit image MIME allowlist.
• Includes a static golden fixture to pin the image wire format.
• Payload-size policy and object URL lifetime remain application concerns.

Scope

This PR is only the reusable codec: 9 files, +346/-2.

Playground UI, remote-sync presets, benchmarks, and the 1 MB JPEG fixture are intentionally separate.

Validation

• Codec tests: 6/6
• Package TypeScript build
• Package tarball/exports verification