docs(changelog): uuidv7 canonical ids entry

[indykish]

Companion to agentsfleet/agentsfleet#547 — the changelog entry for the identifier change that PR ships.

The API and agentsfleet CLI now reject an uppercase or mixed-case UUIDv7 instead of accepting it. Postgres folds ::uuid to lowercase while Redis dedupe keys and cache keys do not, so one entity could carry two spellings that behaved differently depending on which storage boundary it crossed.

Scope

One <Update> block, append-only — no historical entry was touched (+15 / -0 at the time of writing, rebased since onto the trimmed history from #153).

No page revisions needed. I surveyed the repo before writing: zero pages mention UUIDv7, and every UUID example across all .mdx files is already lowercase. The changelog entry is the only content this behaviour change requires here.

Land together

This should merge alongside agentsfleet/agentsfleet#547 — the entry describes behaviour that only exists once that PR ships.

Verification

make lint — exit 0 (Mintlify broken-links check clean).

🤖 Generated with Claude Code

Greptile Summary

Adds a changelog entry documenting canonical lowercase UUIDv7 identifiers.

• Explains API and CLI rejection of uppercase or mixed-case identifiers.
• Documents both reachable API error codes and migration guidance.
• Notes failure behavior for clocks before the UUIDv7 representable range.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
changelog.mdx	Adds the UUIDv7 canonicalization changelog entry and fully addresses the previously reported error-code, upgrade-guidance, and breaking-tag issues.

_{Reviews (4): Last reviewed commit: "docs(changelog): tag the canonical-id en..." | Re-trigger Greptile}