refactor: replace overloaded surface terminology

packages/llm/llm-pi-ai/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/llm/llm-pi-ai/README.md
-README.md: f6a1eefe6083d801009a5b788a07b58d6e696a5a
+README.md: abf1924a1d1297a8fb7300710223886ccf8bc931
 README.zh.md: f4c5ddd6dbe05ae709145cfac341f17a716bac82

packages/llm/llm-pi-ai/README.md

@@ -143,7 +143,7 @@ If a listener rewrites assembled assistant content, the loop drops replay state
 - pi-ai reports failures as in-stream error events; these map to `finish {kind:'error'|'aborted', failure}` chunks. Provider-specific error text distinguishes terminal `QUOTA` from transient `RATE_LIMIT`, while text and usage signals evaluated against the resolved model's context window normalize overflow to `CONTEXT_WINDOW_EXCEEDED`. A terminal `stop` whose message carries no content blocks maps to a `finish {kind:'error'}` with code `EMPTY_RESPONSE` (retried by default policy) instead of a successful empty message.
 - pi-ai folds reasoning tokens into output usage; there is no separate reasoning count to map.
 - pi-ai's `off` thinking level crosses the Harness capability seam unchanged and becomes an omitted pi-ai common `reasoning` option at dispatch.
-- `GenerateOptions.stop` is rejected with `UNSUPPORTED_OPTION` because pi-ai's common streaming surface cannot guarantee it across providers.
+- `GenerateOptions.stop` is rejected with `UNSUPPORTED_OPTION` because pi-ai's common streaming UI cannot guarantee it across providers.
 
 ## App attribution