Current Limits

Honest reference for implemented behavior, caveats, and schema-supported features that need executors.

This page exists so docs do not overpromise. The local runtime is durable and useful, but it is a recorded/transform replay engine, not a live causal simulator.

Runtime And Replay

Area	Current state
Recorded replay	Supported. Base events are copied, branch interventions patch recorded events, fixtures can substitute divergent tool results.
Branch checkpoint bounds	Supported. Targets at or before the branch checkpoint are reported and not patched.
Live model replay	`pinned-live` and `compatible-live` are schema-supported, but local replay errors without an explicit model executor.
Live tool replay	`live-readonly` and `live-explicit` are schema-supported, but local replay errors without an explicit tool executor.
Downstream recomputation	Not claimed. Without an executor, isplay cannot prove how a model would respond after a patched event.
Native framework replay	Adapters capture evidence; replaying through framework execution requires runtime-specific support.

Jobs

Area	Current state
Replay `wait=false`	Enqueues a Graphile Worker job and records durable job events.
Experiment `wait=false`	Enqueues a Graphile Worker job and records durable job events.
`isplay start`	Starts the API and local worker.
Job SSE	Reads stored job events from `/v1/jobs/{id}/events`.
Diff/metric/export jobs	Not separately scheduled yet; replay execution writes current diffs and metrics.

Experiment Limits

Area	Current state
`trialPlan.concurrency`	Parsed, but the current experiment runner is serial.
`trialPlan.maxReplays`	Present in schema; runner mainly uses repetitions.
`trialPlan.stopRule`	Parsed, not fully enforced.
`arm-comparison`	Returns trial matrix shaped data today.

Redaction Limits

Capture policy actions are implemented as capture, drop, hash, and mask.

Action	Current state
`hash`	Emits `[HASHED]`, not a digest.
`mask`	Emits `[REDACTED]`.
`drop`	Replaces the field or matched subtree with `null` and increments dropped-field reporting.
`encrypt`, `artifact_only`, `metadata_only`	Not capture policy actions in v0.3. Use explicit artifact/context metadata instead.

Storage Caveats

Event append is transactional, sequence-contiguous, and conflict-detecting.
Terminal runs reject later event appends.
Artifact reads verify the stored SHA and throw explicit missing/corrupt errors.
Local filesystem artifact storage is not a distributed object store; back it up and mount it durably in production.

Adapter Caveats

Adapter	Caveat
Adapter kit	Requires an explicit `client` or `projectId`; strength depends on where you wire it.
AI SDK	v6 middleware is built for `wrapLanguageModel`; streams are finalized when consumed.
Mastra	Explicit helper adapter, not transparent `Agent.generate` middleware.
LangGraph	Tool events without matching starts become observed events.
Codex	Built-in tool injection is not universally pre-execution. JSONL ingestion maps known item types only.
Claude Code	Model replay is unsupported; model capture is observability-oriented.
OpenClaw	Native synthetic fixture replay only works when the runtime honors before-tool synthetic outputs.

When describing a feature that is schema-supported but not executor-supported, say "modeled" or "schema-supported", not "available".