/ce-compound

Outcome: one qualifying solved problem is written as a durable learning under <root>/solutions/, grounded against the current tree, discoverable by the next agent.

Done: a qualifying doc is written or updated, its frontmatter and claims validated, vocabulary capture recorded, and the mode's completion report emitted; when no learning qualifies, nothing is written and the report says why.

One learning per run. A session that produced several gets several sequential runs, never one batched run. Read references/research.md; it explains what batching breaks.

Preconditions

Document only a problem that is solved and verified.

A learning earns its place only when it holds durable project reasoning that is not readily recoverable from the final code, tests, types, comments, or existing documentation, and losing it would plausibly cause recurrence, material risk, or substantial rediscovery. Apply this counterfactual: if the learning document disappeared, would a future engineer reading the final implementation still be likely to repeat the mistake or redo substantial investigation? Completion, effort, and diff size do not establish eligibility.

If the counterfactual fails, write nothing and report why. Judge this from the session rather than asking. An explicit invocation requests the judgment now but does not lower the bar.