Sley 2.0: an open-source protocol that makes coding agents report omissions and retry rules
GreyforgeLabs · reddit · 2026-09-26
Greyforge Labs released Sley 2.0 (Apache-2.0), a source-file-free coding system where agents talk to a deterministic kernel over the SMP1 framed protocol. Two protocol ideas are broadly useful for anyone designing tool interfaces for models:
- Every response reports what it left out: each frame carries a bounds record stating applied limits, returned entities/edges/bytes, and truncation status. Paging is opt-in — with continuation enabled, oversized pages return a cursor for query.continue; without it, queries fail with QUERYREQUIREDFACTOMITTED rather than returning partial results.
- Refusals carry a retry class: 5 error symbols are retryable after requerying the current head (e.g. STALEROOT), 28 after changing declared limits (e.g. QUERYRESOURCELIMIT), everything else never. v2.0.1 removed a flawed suffix-based retryability rule that let REFCASSTALE retry just because it ends in STALE; unknown codes now default to "never", preventing accidental retry loops.
The kernel judges every change in 14 ordered phases, committing atomically with a receipt, and an independently written Python oracle must reproduce the Rust kernel's bytes exactly. 37 methods cover sessions, queries, candidates, commits, branches, merges, exchange, GC and execution. The public candidate builder isn't shipped yet, and a benchmark comparing agents on Sley vs raw source is still running.
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