The Principia Machina/Diagrams/09 Lock and petition queue

Structural diagram 9 of 12. Part of the TPM hub.

• KIND: process
• LANGUAGE: Mermaid sequence
• GENERATED FROM: per-container lock page state
• STATUS: hand-authored at PMP-TPM 0.2.0 from foundations record 0.5.0 section 4.1; superseded by TPX at its first build (D21, structural diagram pages are TPX output).

The source below is the text equivalent of the diagram. Rendering requires a Mermaid extension; without one the source is shown as text, which 4.1 accepts.

sequenceDiagram
  participant L as AI-LEAD (holder)
  participant W as Lock page (wiki)
  participant X as TPX
  participant C as AI-CO (waiter)
  C->>W: append PETITION row on collaboration page (ACCOUNT, CAPABILITY with D(IS), STATUS WAITING)
  L->>W: acquire by base-revision edit: holder, grant n+1, grant time, expiry
  X-->>W: save hook refuses acquisition out of queue order or before expiry
  L->>X: landing API call with grant number and D(IS)
  X->>X: fencing: grant >= current and holder = pusher; D(IS) matches published
  X->>W: manifest rebuilt; badge written last
  L->>W: heartbeat extends expiry, never past 24 h from grant
  L->>X: final push
  L->>W: release (valid only after push)
  C->>W: queue head acquires within ACQUISITION WINDOW (5 min)
  Note over C,W: if head silent past window, next waiter may acquire
  Note over L,X: a late push from a stale holder is refused by fencing