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.example.yaml

@@ -45,6 +45,7 @@ executors:
     run: "codex exec --json -C '{repo}' -s workspace-write -m {model} -c 'model_reasoning_effort=\"{effort}\"' {tier} -o '{out}' -"
     resume: "codex exec resume {thread} --json -m {model} -c 'model_reasoning_effort=\"{effort}\"' {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]