V3 permits external event, source and content identities and additional
request-tool fields. Copying those values into V4 can give an old plugin
named tool a core source identity, turn old tool-addition content into a
registry instruction, or activate formerly ignored deferLoading and delivery
metadata. Rejecting such collisions would instead refuse valid source logs.
Keep historical extensions in the existing extensible JSON representation.
Prefix unknown content and ignorable event tags with plugin:, preserving
all other content fields and opaque event payloads. Prefix external source
identities with plugin:plugin: or plugin:source: so wrapper and direct kinds
cannot collide even when original names already contain a category prefix.
Known first-party mappings remain explicit and unchanged.
Prefix extra request-tool field names and block-start field names with
plugin:, retaining exact values and existing-prefix doubling. Core schema
parameters, arguments, replay state and nested plugin data are not traversed.
Keep future-generation delivery records inactive after header promotion.
Pin the V3 event vocabulary independently of the current writer and provide
an offline verifier against an explicitly selected historical source commit.
Attachment authorization and export inspect declared event content only.
Team checkpoints preserve all own keys of unknown JSON blocks while still
rejecting malformed known content and retired core tool-result blocks.
Exercise physical read/write/reopen, prefix injectivity, own __proto__ keys,
provider opacity and retained source-identity snapshots.
No generic extension block, metadata wrapper or new schema-tooling type is
introduced. V4 type declarations, persistence schema, checkpoint and frozen
V0-V3 codecs remain unchanged. Canonical tool-result lifting and incomplete
child-catalog policy remain separate concerns.
Adapted from the extension-preservation work in 7ba7e174dd1 by Tianyi Cui.
Co-authored-by: Tianyi Cui <53024+tianyicui@users.noreply.github.com>
Tianyi Cui