fix: multi-user distillation + datetime in context + session log labels

Distillation was silently operating on scott/inara for all users due to
ContextVar defaults. All three distill endpoints now require ?user=&persona=
query params and validate them via persona.validate(). Memory distiller
signatures changed from Optional to required positional args — no more
global settings fallback. Scheduler now iterates all users/personas instead
of hardcoding the primary user.

- context_loader: inject current date/time as first system prompt section
- session_logger: use get_user()/get_persona() from context instead of
  settings globals so Holly/Brian sessions show correct speaker labels
- memory_distiller: system prompts now reference u.title()/p.title()
  instead of settings.user_name/settings.agent_name
- distill router: Query(...) enforces params; _resolve() validates persona
- scheduler: _all_personas() helper iterates every user/persona for distill
- app.js: runDistill() now appends ?user=&persona= via _fileParams

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/memory_distiller.py

@@ -74,7 +74,7 @@ def distill_short(username: str | None = None, persona: str | None = None) -> di
     }
 
 
-async def distill_mid(username: str | None = None, persona: str | None = None) -> dict:
+async def distill_mid(username: str, persona: str) -> dict:
     """
     Ask the LLM to summarize MEMORY_SHORT.md → MEMORY_MID.md.
     Uses DISTILL_BACKEND_MID if set (e.g. "local"), otherwise primary_backend.
@@ -82,8 +82,7 @@ async def distill_mid(username: str | None = None, persona: str | None = None) -
     from llm_client import complete
     from persona import set_context
 
-    u = username or settings.user_name.lower()
-    p = persona or settings.agent_name.lower()
+    u, p = username, persona
     set_context(u, p)
 
     inara_dir = _persona_path(u, p)
@@ -93,13 +92,15 @@ async def distill_mid(username: str | None = None, persona: str | None = None) -
         return {"error": "MEMORY_SHORT.md is empty — run distill/short first"}
 
     budget_tokens = settings.memory_budget_mid
+    persona_name = p.title()
+    user_name = u.title()
     system_prompt = (
-        f"You are {settings.agent_name}'s memory distillation system. "
+        f"You are {persona_name}'s memory distillation system. "
         "Summarize the following recent session logs into a concise mid-term memory digest. "
         f"Target length: under {budget_tokens} tokens. "
         "Focus on: recurring themes, important decisions made, ongoing projects, "
-        f"{settings.user_name}'s current state and priorities, and anything that should persist into future sessions. "
-        f"Write in first person as {settings.agent_name} (e.g. '{settings.user_name} and I worked on...'). "
+        f"{user_name}'s current state and priorities, and anything that should persist into future sessions. "
+        f"Write in first person as {persona_name} (e.g. '{user_name} and I worked on...'). "
         "Use markdown headings. Be specific and concrete — no filler."
     )
 
@@ -126,7 +127,7 @@ async def distill_mid(username: str | None = None, persona: str | None = None) -
     }
 
 
-async def distill_long(username: str | None = None, persona: str | None = None) -> dict:
+async def distill_long(username: str, persona: str) -> dict:
     """
     Ask the LLM to integrate MEMORY_MID.md into MEMORY_LONG.md.
     Uses DISTILL_BACKEND_LONG if set, otherwise primary_backend.
@@ -134,8 +135,7 @@ async def distill_long(username: str | None = None, persona: str | None = None)
     from llm_client import complete
     from persona import set_context
 
-    u = username or settings.user_name.lower()
-    p = persona or settings.agent_name.lower()
+    u, p = username, persona
     set_context(u, p)
 
     inara_dir = _persona_path(u, p)
@@ -146,8 +146,9 @@ async def distill_long(username: str | None = None, persona: str | None = None)
         return {"error": "MEMORY_MID.md is empty — run distill/mid first"}
 
     budget_tokens = settings.memory_budget_long
+    persona_name = p.title()
     system_prompt = (
-        f"You are {settings.agent_name}'s long-term memory curator. "
+        f"You are {persona_name}'s long-term memory curator. "
         "You will receive the current long-term memory and a recent mid-term digest. "
         f"Integrate the new information into the long-term memory. Target: under {budget_tokens} tokens. "
         "Rules: preserve important historical facts; update or replace stale information; "
@@ -170,7 +171,7 @@ async def distill_long(username: str | None = None, persona: str | None = None)
     now = datetime.now().strftime("%Y-%m-%d %H:%M")
     if not response_text.lstrip().startswith("# MEMORY_LONG"):
         response_text = (
-            f"# MEMORY_LONG.md — {settings.agent_name} Long-Term Memory\n\n"
+            f"# MEMORY_LONG.md — {persona_name} Long-Term Memory\n\n"
             f"*Last distilled: {now} via {backend}.*\n\n---\n\n"
             + response_text
         )