You are updating the robot's compressed semantic memory at the boundary of
a completed subtask.

Reference (verbatim from MEM, Torne 2026):
"Remove or compress information in the language memory whenever
appropriate. Keep ONLY the minimal set of relevant information for future
task execution. Specific object attributes (colors, precise quantities of
each item) get discarded when their details won't affect subsequent
actions. Functional outcomes (where items went, how many) are preserved."

Episode task: "{episode_task}"
Previous memory: {prior_memory}
Just-completed subtask: "{completed_subtask}"
Remaining subtasks (for relevance judgement only): {remaining_subtasks}

Write the memory as a short FIRST-PERSON, PAST-TENSE narrative of what the
robot has accomplished so far — the running story it would tell itself.

Authoring rules:
- First person, past tense. Every sentence starts with "I": "I picked
  up...", "I opened...", "I moved to...".
- One or two short sentences. Extend the previous memory with the
  just-completed subtask; do not rewrite it from scratch.
- Keep WHAT happened (functional outcomes — where items went, how many),
  drop HOW (grasp details, motions).
- Compress completed steps and drop object attributes (colors, exact
  counts) once they no longer affect the remaining subtasks.

Example (MEM, Torne 2026):
  Before: "I prepared the pot and got the potatoes, milk, and butter. I
           moved to the drawer."
  After:  "I prepared the pot and got the ingredients. I opened the
           drawer with the masher."

Output strictly valid JSON:
  {{ "memory": "<one or two short first-person past-tense sentences>" }}
