practice: the chain table — every reasoning chain in one selectable overlay (owner-approved plan, 2026-09-29)

- core formatChainLine: names + arrow one-liner, singleton marker, pure
- graph-view Chains button (chrome row, empty-graph hidden) opens the
  overlay: fuzzy search (names/aliases/statements), collapsible chain →
  member → statement rows, birth-session + created columns, no
  understanding-levels column
- pinned Selected section derives the agents' actual input live
  (chainsForSelection over the selection; premise without its
  conclusion shows as the singleton it becomes)
- Generate opens the creation dialog in CUSTOM mode: selection summary
  + dated default title, posts {nodeIds, params, note}; cluster mode
  untouched on /practice
- live-verified on the owner's dev server: 219 chains, derived preview,
  search-never-filters-Selected, dialog handoff (selection pass-through
  bug caught + fixed en route), Esc/backdrop dismiss, zero writes
- practice UI files re-normalized to tabs (my earlier prettier runs had
  drifted them to the 2-space default; whitespace-only)

17 render/unit pins added; gates: tsc 0, 1174/1174, lint 0, build 0

src/core/practice.ts

@@ -91,6 +91,24 @@ export function chainsToGraph(
 	return { nodeIds: [...nodeIds].sort(), edges };
 }
 
+/** A chain as one world-facing line — the propositions' NAMES joined
+ *  by the derivation arrow: "Premise one, Premise two → Conclusion"; a
+ *  singleton shows its "(no premises)" marker. Pure + browser-safe:
+ *  the shell (chain table, derived previews) cannot import the agent
+ *  module — the level tables set this precedent. Unknown ids fall back
+ *  to the raw id (honest, never guessed). Premises sort by id — the
+ *  same determinism law as chainsForSelection. */
+export function formatChainLine(
+	chain: Pick<ReasoningChain, "premises" | "conclusion">,
+	propositions: Readonly<Record<string, { name: string }>>,
+): string {
+	const nameOf = (id: string) => propositions[id]?.name ?? id;
+	const premises = [...chain.premises].sort().map(nameOf).join(", ");
+	return premises !== ""
+		? `${premises} → ${nameOf(chain.conclusion)}`
+		: `${nameOf(chain.conclusion)} (no premises)`;
+}
+
 /** chainCoverage()'s report. `missing` fails the partition; `duplicated`
  *  is informational — a chain MAY legitimately be exercised by several
  *  problems (the operations make that sound). */