fix(schema): add minProperties guard + finite numeric maximums (P3 schema hardening)

[yshengliao]

Summary

Closes the P3 "Schema hardening" open item from REVIEW.md.

• animations must be non-empty — the compiler now rejects animations: {} with InvalidGraphError("animations must declare at least one animation"), mirroring minProperties: 1 already in the JSON Schema file.
• Finite maximums for duration fields — defaultFrameDuration and per-frame duration are capped at MAX_DURATION = 86_400_000 ms (24 hours). Values above this are rejected with InvalidGraphError.
• Finite maximum for speed — state speed multiplier is capped at MAX_SPEED = 1_000. Values above this are rejected with InvalidGraphError.
• JSON Schema updated — duration (frames), defaultFrameDuration, and state speed gain matching maximum constraints so editors and CI validators agree with the runtime.

Rationale for chosen bounds

Field	Maximum	Rationale
duration / defaultFrameDuration	86 400 000 ms (24 h)	Eliminates accidental huge values (e.g. copy-paste of a Unix timestamp). No real animation frame should last a full day.
speed	1 000	A 1000× multiplier already compresses a 100 ms frame to 0.1 ms; anything higher is indistinguishable from zero-duration.

Non-finite values (Infinity, NaN) were already rejected by the existing guard — these new maximums close the gap for finite-but-absurd values.

RED → GREEN evidence

4 tests were added first (RED), then the runtime and schema were fixed (GREEN).

RED run (before fix):

• rejects an empty animations map with 'at least one animation' message — FAIL (wrong error message)
• rejects a frame duration above the 24-hour ceiling — FAIL (did not throw)
• rejects defaultFrameDuration above the 24-hour ceiling — FAIL (did not throw)
• rejects a state speed above 1000× — FAIL (did not throw)

GREEN run (after fix): 140/140 tests pass.

Test plan

• pnpm test — 140 tests, all green
• pnpm prepublishOnly — typecheck, lint, coverage 100%, build, verify:dist/exports/llms, check:size all pass
• Schema: aispritejs/schema subpath exports the updated JSON Schema with minProperties:1, maximum:86400000, maximum:1000

Notes for leader

• No version bump, no CHANGELOG edit (leader owns release).
• Public API unchanged — this only tightens validation.
• STABILITY.md and README.md already note that schema hardening improves editor feedback without replacing runtime validation. The new bounds are consistent with that framing; no release-doc edits needed beyond what the leader decides to add at release time.
• llms-full.txt verified up-to-date (verify:llms passed).

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR hardens SpriteGraph validation to better align runtime checks with the published JSON Schema, preventing empty animations maps and rejecting finite-but-absurd numeric values for durations and state speed.

Changes:

• Add runtime guard rejecting animations: {} with a dedicated InvalidGraphError message.
• Enforce maximum allowed values for defaultFrameDuration, per-frame duration, and state speed in the compiler.
• Update the JSON Schema to add matching maximum constraints, plus add tests covering these bounds.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
test/validation.test.ts	Adds tests asserting rejection/acceptance at the new MAX_DURATION and MAX_SPEED ceilings and the new empty-animations error message.
src/sprite/compile.ts	Adds compiler-time validation for non-empty animations and maximum caps for durations and speed.
schemas/aispritejs-graph.schema.json	Adds maximum constraints for frames.*.duration, defaultFrameDuration, and states.*.speed to match runtime validation.

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