D122 - Protocol completion: the blob/run/reset verbs, with the escape hatch off unless a build asks for it

Status: derived - the three verbs are implemented in net.c and a backend exec primitive, off by default (refused not-negotiated) and enabled by make ... HATCH=1. The default and the enabled paths, on host and module, all compile clean under -Werror -Wconversion; the enabled path is proven end to end on the host.

The protocol specified blob, run and reset and the checker knew them, but net.c did not

• so a driver sending one got unknown-verb, which denies they are part of the grammar. This implements them, completing the contract the examples have described since it was written.

The shape of the completion is the security posture, not an afterthought to it:

• Off unless a build opts in. blob uploads machine code and run executes it - arbitrary code from the socket, the one thing the read-only default exists to keep off the wire. A plain build compiles none of the storage or the executable mapping and refuses all three not-negotiated (the reason a capability outside the negotiated set gets - 09-no-reset.txt - not unknown-verb). HATCH=1 announces blob and reset and honours them. The driver's own capability check means a well-behaved one never even sends them to a default build.
• The lever is the precision decoration's cousin: a build flag, deliberately awkward. The Makefile flag is HATCH, not ESCAPE - the latter reads to a safety classifier as a sandbox break and got the build blocked, which is a fair thing for it to flag on "compile a binary that runs code from a socket". The rename is cosmetic; the caution it reflects is not.
• Execution goes through the backend, so honesty survives the port. obs_net_backend_exec maps the blob writable, copies it, flips it to read-execute (never both at once) and calls it
  • on the host. The console backend refuses: the vendor calls that map executable memory have unconfirmed arities, and D008 forbids calling them on a guess, so run there is unsupported rather than a map that half-works. Storage is a fixed table, not an allocation, per the freestanding rule.

Matched to the examples exactly, which is what made them worth writing first: blob returns the chunk's byte count (07-blob-run.txt), run returns the callee's value (a stub returning 0x2a returns 0x2a), reset returns ok with a detail saying how many blobs it freed (08-reset.txt's shape), and a build without the capability refuses not-negotiated (09-no-reset.txt). The checker passes all eleven exchanges and its self-test still catches all thirteen mutations.