[TheGreatAxios]

What changed

When someone approved a document, the coordinator often replied "it's ready for approval" and started nothing, so the project sat still until they typed again. Now it moves on by itself, and still waits when the person asks it to.

• After an approval, the hub tells the coordinator what can start now. The writer, designer and coder each have one gate, the rule they already refuse with, and the approval lists every step whose gate passes and that is not already made or under way. Loosening a gate later loosens what the coordinator is told, so the order lives in one place.
• If the coordinator then replies without starting anything or asking the person something, it is reminded once. A second reply goes through, so "approve it, but hold off" is respected.

How it was verified

Replays of real conversations right after an approval:

The person said	main	this PR
"Go with your recommendation" (the original stall)	started the next step 0 of 10	10 of 10
"Approve, then hold off"	waited 10 of 10	waited 5 of 5
"Looks good, stop here for a sec"	waited 10 of 10	waited 5 of 5
"…until I say banana"	waited 2 of 2	waited 3 of 3
"Stop."	stopped 1 of 2	stopped 3 of 3
"ya kool whatevr"	started the next step 1 of 2	3 of 3
"Skip the requirements, go to design"	wrote the requirements 1 of 2	3 of 3
Imported project, "add a feature"	asked or read first 10 of 10	5 of 5

Two live projects through to the design:

• OpenAI, with a question right after approving, "don't do anything until I say banana", and "hold off" followed by "actually go": each wish was followed, with no freezes and never more than one writer at a time.
• xAI, asking to skip constraints, approaches and the design: the coordinator explained what the hub needs and carried on, with no loops or made-up values.

Lint, typecheck and tests pass.

Closes CL-12183

[linear-code]

CL-12183

[corbits-triage]

Merged before Triage finished on e1e41fb.

The merge-base changed after approval.