Module checkpoint 

Workload checkpointing — see SRD-44.

Submodules:

• identity — PathSegment, PhaseIdentity, and the per-phase canonical-program hash. Identity is per-phase (no workload-level identity tuple) and (yaml_path, coords) is necessary; the program hash is sufficiency.
• storage — JSON file format + atomic-rename writer.
• writer — CheckpointWriter actor: subscribes to phase-lifecycle events, flushes on the metrics-tick cadence with sqlite-fsync-then-checkpoint-fsync ordering.
• resume — resume planner: loads checkpoint, classifies each freshly-pre-mapped phase per the resume protocol, produces a ResumePlan the executor consults before dispatch.

Re-exports

pub use events::CheckpointData;

pub use identity::PathSegment;

pub use identity::PhaseIdentity;

pub use resume::ResumeAction;

pub use resume::ResumePlan;

pub use storage::Checkpoint;

pub use storage::OpCounts;

pub use storage::PhaseEntry;

pub use storage::PhaseStatus;

pub use writer::CheckpointWriter;

Modules

events

SRD-44a — Checkpoint event taxonomy.

identity

Per-phase identity for checkpoint match / mismatch decisions.

params_scope

SRD-107 — the consumed-params derivation.

resume

Resume planner — classify each freshly-pre-mapped phase against the saved checkpoint document and emit a ResumePlan the executor consults before dispatch.

storage

Checkpoint storage — fold-state types + JSONL event-log reader.

writer

CheckpointWriter — append-only event-log owner for the per-session checkpoint document. SRD-44a §“Writer behaviour”.

Functions

declare_scene_tree_phases

Declare every phase node in a freshly-pre-mapped scene tree to the writer. Called once at session bootstrap, immediately after [crate::executor::pre_map_tree] returns. Each phase gets a Pending entry with no hash; the runtime updates the hash via CheckpointWriter::update_phase_hash when the phase compiles.

scene_tree_resume_candidates

Build a list of (identity, declared_idempotent) pairs for every phase the scene tree will execute. The runner feeds this to ResumePlan::from_checkpoint when resuming, so the planner can classify each freshly-pre-mapped phase against the saved document.