Tooling: Reliving debugger UX (Constraint Lens + Provenance Heatmap)

[flyingrobots]

Pulse ideas to make a complex deterministic scheduler debuggable:

Concepts

1. Constraint Lens: per-tick overlay showing why each step ran (preconditions, resource caps, scheduler rule, blocked alternatives) + ability to scrub and try counterfactual constraints.
2. Provenance Heatmap: visualize diffusion / blast radius of a change over the provenance/execution graph over time; highlight low-cohesion changes.
3. Reliving (movie scrubbing): timeline scrubber where each frame shows a minimal causal slice and supports branching/forking from any tick.

Why this matters for Echo

Echo already has:

• deterministic ticks/worldlines
• receipts/causal logs (or planned)

These UX tools make the determinism usable for debugging + incident triage.

MVP (read-only)

• Define data shapes:
  • AdmissionTrace / ConstraintPayload per tick/step (predicate IDs, rule-pack hash, resource snapshot)
  • CounterfactualRequest (which constraint changed + new value)
  • CohesionRollup per tick (blast radius, diffusion edges)
• Record these during normal runs (no UI yet) and ensure they are replayable from logs.

Stretch

• Add 1-2 counterfactual sliders (CPU cap, priority weight) and measure Decision Delta Coverage.
• Build UI panels in the existing viewer.

Acceptance criteria

• Given a saved run log, a tool can render a per-tick constraint report deterministically.
• Cohesion metric produces stable output for the same run.

(Also applies to Engram/JITOS, but Echo will likely drive implementation first.)