steps callers: the runner, the indexer, the operator and sessions (D-18); BLD12 builds in the fetch;
BLD13 resolved and the toolchain digest; BLD14 the step key <asker>.<node>.<id> beside main's
<node>.<id>; the events toolchain-reported and step-progress on the three build seats, and
step-progress on mesh-wants.
Builds: design 47 G §463, §480, §465, §466, §467, §481, §483, §492, §496
Claude-Session: https://claude.ai/code/session_01JG73KEq4zoDfM9WtYpcQgZ
Builds: design 47 G §22, §116, §206, §271, §326, §338 (callers: steps the runner
and the indexer, drop the runner and the builder, kept-artifact the node-engines),
§24, §331 (step-ended.<node>, 128 MiB), §370, §373 (the ask carries the version and
each package member's digest), §203, §324 (acts build on the language).
Not yet in this commit, left as the dev branch built them and not read against the
lines: the accepted kind names (dev's 'step'; G-9 §415 names check.step, check.run,
delivery.step), the state rename detected-steps (G-9 §414).
Claude-Session: https://claude.ai/code/session_01JG73KEq4zoDfM9WtYpcQgZ