tia.handoff

tia.handoff — prepare the gate, let a human act (class GATE)

The harness is an assistant up to the gate, never an autonomous commissioner. Anything that touches the physical controller, the network, secrets, or safety stops here: this skill assembles the approval envelope (requires_human_action) — what can be done, what the human must do, the plan + hash, and the exact resume call — and then stops.

When to use

• After tia.verify is clean and the user wants to download / deploy / go online / scan / commission.
• Whenever a step needs a secret (master secret / UMAC) or touches F (safety).

The gates (and the tool that fronts each)

Gate	Action	Tool	What the human must approve
G1	open/connect project (1st time)	tia_connect (+ tia_show_ui)	confirm the TIA trust dialog on the serve host
G3	download (CPU STOP → overwrite → restart)	tia_download	the load preview: StopAll, OverwriteSystemData, StartModule
G4	go online (connect to live CPU)	tia_online	it is safe to connect to the target machine
G7	network scan (accessible devices)	tia_accessible_devices	probing the local network via the PG/PC NIC
G6	master secret / UMAC	tia_mastersecret_set, connect umac*	supply the secret (human/credential vault)
G5	safety/F author·modify·download	—	never autonomous; F deploy is a human, gated action

Procedure (in order)

1. Precondition (Gd9). Confirm the latest tia_compile is clean (errors:0) via tia.verify. Never prepare a download for an inconsistent project.
2. Discover the path (G7, gated). Connection mode / PG-PC interface / target interface are localized names — discover them with tia_accessible_devices (needs confirm:true, a network scan → itself a gate) or tia_connections_diagnose.
3. Dry-run the download. tia_download { dryRun:true } → returns plan, planHash, loadPreview (StopAll / Overwrite / StartModule), and the Gd9 note. Nothing is sent.
4. Emit the handoff envelope (requires_human_action):
   • canDo — e.g. "download to PLC_1".
   • youMustDo — the concrete physical consequence (the CPU will STOP, system data is overwritten, the CPU restarts) + confirm it is safe on the target line.
   • plan + planHash — the exact binding.
   • resume — the precise call a human runs after approving: tia_download { approved:true, planHash:"<the hash>", ... } (the same plan; the hash binds approval to the reviewed plan).
5. STOP. Do not call tia_download with approved:true yourself. A human approves out-of-band and runs the resume call (or explicitly instructs you to, with the hash).

Hard guarantees

• Never auto-approve / auto-deploy. This skill outputs a plan + the resume instructions; it does not perform the gated action. approved:true + a matching planHash only ever come from an explicit human decision.
• Secrets are human-supplied (G6). Master secret / UMAC password come from a human or a credential vault — never invented by the AI, never logged, never put in .mcp.json.
• Safety never autonomous (G5). F-program author/modify/download is always a gated, human action. The harness only reports F (signatures); the safety-reviewer is read-only.
• Plan binding. The download executes only with the exact planHash from the dry-run — a changed plan invalidates the approval (re-review).