Per-model service tier default (codex: gpt-6.1-sol -> fast), tier:<x> / tier:none labels

executors.<x>.tier_defaults maps a model to the tier used when no label sets one;
a tier:<name> label sets it explicitly and tier:none drops the tier argument.

config/agentd.yaml

@@ -44,6 +44,7 @@ executors:
     # `exec resume` takes no -C/-s: the runner already cd's into the repo, the sandbox goes in as a -c override
     resume: "codex exec resume {thread} --json -m {model} -c 'model_reasoning_effort=\"{effort}\"' -c 'sandbox_mode=\"workspace-write\"' {tier} -o '{out}' -"
     tier_arg: "-c 'service_tier=\"{tier}\"'"
+    tier_defaults: {gpt-6.1-sol: fast}   # tier when no label sets one (`tier:<x>`, `tier:none` = no tier)
     thread_from: events.jsonl:thread.started.thread_id
     last_message: '{out}'
     models: [gpt-6.1-sol, gpt-6-astra]