Append-only hiring-events ledger exposed as an 'agent data plane'

SIGNALSAPIManage supplier listing

Append-only hiring-events ledger exposed as an 'agent data plane': every observation of a requisition on a company's ATS or job board is written as an event rather than overwriting a row — three event types (opened = never-seen-before requisition, reposted = same requisition reappearing after a gap, reobserved = still present). No silent mutations, so the history stays intact and replayable. On top of the ledger: six derived primitives — hiring pulse (accelerating/decelerating/surging per company), first hire (when a company opened its first-ever role in a function, i.e. a new budget line), repost pain (roles a company has failed to fill, ranked by repost frequency), ATS migrations (applicant-tracking vendor switches with dates), role demand (market-wide role/geography demand over time), and a change feed with a replayable cursor. Every read carries an as_of timestamp; history-backed reads carry per-value provenance (board, observation time, confidence), and freshness is machine-advertised via X-Data-Freshness and X-Meter-Class headers. Access via REST /v1, an MCP server exposing the same primitives as agent tools, and a Clay HTTP provider for enrichment columns.