condensers.py: 125 pre-existing mutation survivors outside the #196-changed function

[cdeust]

What

A scoped mutmut run for #196 (only_mutate = mcp_server/core/context_assembly/condensers.py, killer suite tests_py/core/context_assembly/test_condensers.py, 352 mutants) surfaced survivors concentrated in the PRE-EXISTING condensers, i.e. code #196 did not change:

• condense_code_block — 29 survived
• condense_assistant_message — 28
• condense_memory_content — 25
• condense_timeline_event — 15
• condense_user_message — 12
• condense_entity_triples — 9
• _split_by_code_blocks / _has_code_blocks / _first_sentence — 7

The #196-changed function (condense_assembled_context) was triaged to 0 non-equivalent survivors in that PR (13 killed by added contract tests, 1 documented equivalent: summaries priority 3→4 preserves the strict sort order).

Why deferred

Per coding-standards §12.5 the blocking per-commit tier mutates only the changed lines; these survivors are the wide-sweep backlog for a module the change touched but whose older functions it did not alter. Outside the #196 blast radius: no behaviour of these functions was changed by the PR.

Reproduction

scripts/mutation_check.sh tests_py/core/context_assembly/test_condensers.py \
                          mcp_server/core/context_assembly/condensers.py

Acceptance criteria

• Every survivor above is either killed by a new contract test or documented as equivalent with a written rationale (§12.1 — no third option).
• The run notes list the final killed/equivalent tally per function.