NameError: name 'estimated' is not defined in estimate_prompt_tokens_chain — tiktoken fallback broken

[rdnot]

Bug Description

estimate_prompt_tokens_chain() in nanobot/utils/helpers.py crashes with NameError: name 'estimated' is not defined when the provider counter is unavailable or raises an exception.

The crash occurs in memory.py:603 → helpers.py:434 during token-based memory consolidation.

Root Cause

Commit d9800ec ("refactor: replace try-except blocks with contextlib.suppress") accidentally deleted the tiktoken fallback line when converting try/except to with suppress():

     provider_counter = getattr(provider, "estimate_prompt_tokens", None)
     if callable(provider_counter):
-        try:
+        with suppress(Exception):
             tokens, source = provider_counter(messages, tools, model)
             if isinstance(tokens, (int, float)) and tokens > 0:
                 return int(tokens), str(source or "provider_counter")
-        except Exception:
-            pass
-
-    estimated = estimate_prompt_tokens(messages, tools)
     if estimated > 0:
         return int(estimated), "tiktoken"
     return 0, "none"

Steps to Reproduce

1. Run nanobot gateway with any provider that doesn't implement estimate_prompt_tokens
2. Send a message that triggers memory consolidation
3. Consolidator calls estimate_session_prompt_tokens() → estimate_prompt_tokens_chain()
4. NameError at line 434

Expected Behavior

After provider counter fails, fall through to tiktoken estimation.

Relevant Logs

nanobot Version

nanobot v0.1.5.post3

Python Version

Other (specify below)

Operating System

Windows

Channel / Platform

WhatsApp

LLM Provider

Other (specify below)

Configuration (Optional)

Additional Context

No response