Function handle_muxspect_migrations 

pub async fn handle_muxspect_migrations() -> impl IntoResponse

GET /api/v1/muxspect/migrations — the migration doctor for THIS instance’s data dir: every registry migration with its applied/pending state and, for applied ones, the same post-condition verdict agentmux-srv migrate --verify prints (SPEC_MIGRATION_SYSTEM_HARDENING_2026_08_03.md Phase 1c). Built by the one producer both share (migrations::doctor_report_for_instance), so an operator inside a running instance gets exactly the answer the CLI would give against a stopped one — without hunting for the srv binary or the data dir. The incident the hardening spec was written about (§1.6: a migration “recorded as applied that wrote nothing”) is exactly a “why did this agent fail to start” question, which is muxspect’s job.

Read-only, like --verify: opens both tracking stores with SQLITE_OPEN_READ_ONLY, never opens a Store, never creates a file. Runs on the blocking pool — it is a handful of SQLite reads, but they are synchronous. exit_code in the body is what --verify would exit with (0 or 3), so the CLI can mirror it.