VerseVDI-Protocol/openspec/changes/fix-terminal-receipt-conformance/proposal.md

Why

The canonical terminal-receipt requirement contradicts the fixed VGF1 grammar and every generated validator, so RC8 cannot provide an executable cross-language contract for gateway-owned terminal closure.

What Changes

• Define client-direction VGF1 type 0x03 as an empty terminal receipt in the existing frame grammar.
• Add fixed conformance vectors for valid receipt handling and invalid direction, body, truncation, length, and unknown-type cases.
• Generate consistent Go, Rust, Swift, and Python validation behavior from the Protocol source.

Capabilities

New Capabilities

None.

Modified Capabilities

• gateway-input-feedback: Make the already-required terminal receipt executable and cross-language conformant without weakening other VGF1 validation.

Impact

Protocol frame documentation, conformance fixtures, generators, generated bindings, native validator tools, and immutable Protocol consumers. RC8 remains unchanged and a new immutable Protocol version is required.