fix(athlete): drop athlete-tag filter, harden write guardrail, guard empty echo

- get_athlete_summary no longer offers a tags filter: the endpoint's tags param
  filters ATHLETES (coach-facing), not activities, so it produced falsely-empty
  or wrongly-unfiltered summaries (confirmed against the OpenAPI description).
- update_sport_settings: an answered elicitation is now authoritative — accept
  without the confirm tick is a refusal that stops WITHOUT emitting the
  confirm=true fallback instructions (an agentic client could use them to bypass
  the refusal), and an explicit confirm param cannot override it. The elicit
  except no longer swallows failures silently (logged), and an empty-body PUT
  echo renders the merged record instead of an empty settings block.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NGzHtDvJur9U7ysgRKRUTN

src/intervals_mcp_server/tools/athlete.py

@@ -6,6 +6,7 @@ Read tools exposing the athlete's profile, per-sport training settings
 coach needs to reason about intensity and readiness.
 """
 
+import logging
 from typing import Any
 
 from mcp.server.fastmcp import Context  # pylint: disable=import-error
@@ -24,6 +25,8 @@ from intervals_mcp_server.utils.validation import resolve_date_params
 # Import mcp instance from shared module for tool registration
 from intervals_mcp_server.mcp_instance import mcp  # noqa: F401
 
+logger = logging.getLogger("intervals_icu_mcp_server")
+
 
 class _ConfirmThresholdChange(BaseModel):
     """Elicitation schema: the user confirms (or not) a threshold change."""
@@ -96,14 +99,15 @@ async def get_sport_settings(sport: str | None = None) -> str:
 async def get_athlete_summary(
     start_date: str | None = None,
     end_date: str | None = None,
-    tags: str | None = None,
 ) -> str:
     """Get a training-load summary (fitness/fatigue/form and totals) over a date range.
 
+    Note: the underlying endpoint's ``tags`` parameter filters *athletes* (a
+    coach-facing feature), not activities, so no tag filter is offered here.
+
     Args:
         start_date: Start date in YYYY-MM-DD format (optional, defaults to 30 days ago).
         end_date: End date in YYYY-MM-DD format (optional, defaults to today).
-        tags: Optional comma-separated activity tags to filter by.
     """
     try:
         athlete_id, api_key = await credentials.resolve_caller_credentials()
@@ -112,10 +116,6 @@ async def get_athlete_summary(
 
     start_date, end_date = resolve_date_params(start_date, end_date)
     params: dict[str, Any] = {"start": start_date, "end": end_date}
-    if tags:
-        tag_list = [t.strip() for t in tags.split(",") if t.strip()]
-        if tag_list:
-            params["tags"] = tag_list
 
     result = await make_intervals_request(
         url=f"/athlete/{athlete_id}/athlete-summary", api_key=api_key, params=params
@@ -213,19 +213,28 @@ async def update_sport_settings(  # pylint: disable=too-many-arguments,too-many-
     sport = ", ".join(str(t) for t in (current.get("types") or [])) or f"settings {settings_id}"
     diff = "\n".join(diff_lines)
 
+    # Guardrail. If the client answers an elicitation prompt, that answer is
+    # authoritative: anything short of accept-with-confirm is a refusal and we
+    # stop WITHOUT emitting the confirm=true fallback instructions (an agentic
+    # client could otherwise use them to bypass the refusal it just received).
+    # Only when elicitation is unavailable (no ctx, or the request itself fails)
+    # do we fall back to requiring the explicit confirm flag.
     approved = False
+    elicitation_answered = False
     if ctx is not None:
         try:
             elicited = await ctx.elicit(
                 message=f"Update {sport} thresholds?\n{diff}", schema=_ConfirmThresholdChange
             )
+            elicitation_answered = True
             action = getattr(elicited, "action", None)
-            if action in ("decline", "cancel"):
-                return "Sport settings unchanged — you declined."
             data = getattr(elicited, "data", None)
             approved = action == "accept" and bool(getattr(data, "confirm", False))
-        except Exception:  # noqa: BLE001 - client without elicitation capability falls through
-            approved = False
+        except Exception as exc:  # noqa: BLE001 - capability absent or elicitation failed
+            logger.warning("Elicitation unavailable, falling back to confirm flag: %s", exc)
+
+    if elicitation_answered and not approved:
+        return "Sport settings unchanged — you did not confirm the change."
 
     if not approved and not confirm:
         return (
@@ -246,5 +255,6 @@ async def update_sport_settings(  # pylint: disable=too-many-arguments,too-many-
     if isinstance(result, dict) and "error" in result:
         return f"Error updating sport settings: {result.get('message')}"
 
-    body = result if isinstance(result, dict) else updated
+    # An empty-body 200 parses to {}; render the merged record in that case.
+    body = result if isinstance(result, dict) and result else updated
     return f"Updated {sport} settings:\n\n" + format_sport_settings(body)