Where the 28m20s (cut@1700s) went, from pi.txt + the pi-subagents child metas: the root read the TTL and wrote a solution ITSELF by turn 7 (18.4k chars of thinking on the write turn), found "No SPARQL engine found" (T009) and tried to finish at ~T010. The machinery then pushed it through the full staged workflow AFTER the answer existed: forced reviewer → scout (136s) → planner (166s) → reviewer #1 (437s, output LOST, see below) → reviewer #2 (237s, found a real blocker) → edit → reviewer #3 (still running at the cut). Children ate ~16 of the 28 minutes on the shared slot.

Three concrete findings:

1. pi-subagents lost a child's report. Reviewer b5ff6e05 worked 7.3 min (8 turns, edited the regex in solution.sparql, ended with a proper ```acceptance-report fenced block, exit 0) but its output.md is EMPTY and the parent saw "(no output)" — the report-extraction appears to eat a final message that is ONLY an acceptance-report block. The parent then (reasonably) ran ANOTHER reviewer, doubling the review cost. Ledger item added.

2. The reviewer added real value. Reviewer #2 caught invalid SPARQL (SELECT subquery nested in FILTER EXISTS); after the fix the query RUNS and selects the RIGHT professor. Verifier compare: MinimalPi (fast__…144656) returned the WRONG professor row; this run returns the right professor with wrong countries aggregation ('GR' vs 'GR, US' — the EU-filter joins away the professor's US affiliation before GROUP_CONCAT). Closer, not there — the remaining miss is reading-comprehension (countries column = ALL the professor's universities, EU filter only gates selection).

3. A reviewer-child thinking turn saturated the 8000-token reasoning budget (31.4k chars ≈ 5 min of decode at ~24 t/s) — on the 122b each child is expensive twice: cold prefill on the shared slot + budget-deep thinking. The "no reasoning-loop pathology" note from casual use does not hold under review pressure.

Also: neither harness variant tried pip install rdflib to self-verify — consistent with preamble RULE 2's "use only the standard library and already-installed tools" steering away from the ONLY verification path on this task (the container has network; the verifier itself installs rdflib). Ledger item added.