feat(math): un-mirror priority_metric (#2571 resolved) + Q2 prev-tick group-votes

[jucor]

Restore the real priority_metric branching formula in BOTH engine modes:
Clojure HEAD passes a real boolean since #2611 (conversation.clj:686, merged
2026-07-18), so the all-49 #1961 bug-mirror (#2571) is no longer the parity
behavior — the correct formula is.

Q2 (CLOJURE_QUIRKS): Clojure's :comment-priorities node SHADOWS its
current-tick group-votes input with (:group-votes conv) — the PREVIOUS
tick's stored value (conversation.clj:658). clojure-legacy mode now consumes
the captured prev-tick group-votes ({} on the first tick == Clojure's nil);
improved mode keeps the current-tick read. The current tick's group-votes
are stored on self.group_votes each tick (both modes, like self.pca) as the
in-memory analogue of Clojure persisting :group-votes in math_main. Restart
seam (from_dict/poller reload of group-votes) deferred to the poller
equivalence phase — noted in journal.

Stale-mirror test sites reworked: the designed xfail on
test_priority_metric_non_meta_squared is harvested (formula test now gates);
TestD12CommentPriorities now pins varied (non-all-49) Python output +
coverage instead of the mirror signature; the exact-value comparison in
test_legacy_clojure_regression.py::test_comment_priorities is xfailed for
ALL variants (reference blobs predate the Clojure #2611 fix — value parity
is validated by the H-B replay battery until blob regen with a fixed
generator).

TDD: tests/test_priority_unmirror.py — RED observed (formula tests fail on
the mirror; prev-tick flow + group_votes storage fail on old wiring), 7
GREEN after. Targeted: 13 passed (unmirror+float-serialization), 21 passed
(D12/priority subset), 4 xfailed (legacy regression value comparisons).

commit-id:a85047a7

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Stack:

• docs(delphi): overnight pre-cutover audit (s6) — CUTOVER_RUNBOOK + journal #2659
• feat(delphi): zid-sharding for the math poller — one shard = one process #2658
• ci: run postgres integration tests #2637
• feat(delphi): poller-equivalence harness (goal condition 2) — PASSES live on vw + pc-meta-02 #2657
• feat(math): moderation + restart replay parity — mod_update, restart-seam restore, Q13-Q18 #2656
• docs(delphi): R1-parity goal docs, journal (2026-07-18 → 07-24 s5), quirks + divergence ledger #2626
• feat(delphi): Q12 carve-out — pin the cold-tick PCA start to ones in both replay drivers #2655
• feat(math): Q11 — replicate vectorz distance cancellation in legacy kmeans #2654
• feat(math): small-N degenerate parity — run the real math on tiny matrices in clojure-legacy mode #2653
• feat(delphi): Q10 carve-out — pin large-conv cutoffs to certify the deterministic full-PCA path #2652
• feat(delphi): replay loader resolves private datasets under real_data/.local #2651
• feat(math): Clojure hash-map iteration order for the in-conv greedy tie-break (legacy) #2650
• feat(math): clojure-legacy blob emission + selection parity — Clojure-exact math_main at step 0 #2649
• feat(delphi): acceptance canonicalization — suppress cross-engine ordering artifacts in certify comparer #2648
• feat(delphi): certify.py battery runner + focuser + fingerprint ledger (Spec A, Phase 0) #2647
• feat(delphi): prodclone extractor — feature-filtered dataset export (Spec B) #2646
• feat(math): un-mirror priority_metric (#2571 resolved) + Q2 prev-tick group-votes #2645 ⬅
• feat(math): participant-ban leak replication in clojure-legacy mode (Q1) #2644
• feat(delphi): Clojure timing probe (Spec C) #2643
• feat(math): degenerate-tick group-clusterings overwrite + <2-participants edge (legacy mode) #2642
• refactor(math): move impl-flag resolver to polismath/utils/env_flags.py #2641
• feat(delphi): Python math poller service (phase 1) — Clojure math-container replacement #2625
• fix(delphi): Clojure-parity math writers + committing write path in PostgresClient #2624
• feat(math): in-conv greedy floor + persistent carry (PR-E) #2623
• feat(math): Clojure-exact base-cluster lineage + warm start (PR-C) #2622
• feat(math): replay harness H-B — Clojure Mode A driver (dev/replay.clj) + cross-language comparer shim #2621
• feat(math): group-k-smoother in clojure-legacy engine mode (PR-D smoother) #2620
• feat(math): PCA warm start in clojure-legacy engine mode (PR-B) #2640
• feat(math): add POLISMATH_ENGINE_MODE flag + prev-tick warm-start scaffolding (PR-A) #2618
• feat(delphi): replay harness H-A — schedule spec+slicer, Python driver, store, step comparer, CLI #2639
• fix(delphi): cold-start generator copies FULL revote history (no DISTINCT ON dedup) #2638
• fix(math): correct comment-extremity sign in pca_project_cmnts (D1b) #2615
• docs(delphi): add math-algorithm history & routing-regression reference #2613

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⚠️ Part of a stack created by spr. Do not merge manually using the UI - doing so may have unexpected results.

[Copilot]

Pull request overview

This PR restores the intended (and now Clojure-HEAD-parity) priority_metric branching behavior and updates the Delphi math pipeline to reproduce Clojure’s Q2 “prev-tick group-votes” quirk in clojure-legacy engine mode, with accompanying test updates to reflect the removal of the historical all-49 mirror behavior.

Changes:

• Un-mirrors priority_metric so non-meta comments use the real importance_metric * decay formula (meta remains constant).
• In clojure-legacy mode, feeds comment priorities using the previous tick’s stored group_votes while storing current-tick group votes for the next tick.
• Reworks/introduces tests to (a) pin the real formula, (b) validate Q2 tick semantics, and (c) mark stale pre-#2611 reference blob value comparisons as xfail.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
delphi/polismath/conversation/conversation.py	Restores real priority_metric logic; threads prev-tick group_votes into legacy comment-priority computation and stores current tick group-votes for next tick.
delphi/tests/test_priority_unmirror.py	Adds focused tests for un-mirrored priority formula and Q2 prev-tick group-votes behavior across engine modes.
delphi/tests/test_legacy_clojure_regression.py	Marks stale blob exact-value comment-priority parity checks as xfail across variants until blobs are regenerated.
delphi/tests/test_engine_mode.py	Adjusts cold-run cross-mode identity test to exclude comment priorities due to Q2 first-tick divergence.
delphi/tests/test_discrepancy_fixes.py	Updates D12 comment-priority tests to assert “varied priorities” (no all-49 mirror) rather than constant-value parity.

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