chain table: the fenced Delete action + multi-node delete dialog (owner ruling)

"This is really the view deletion should be done in" — the chain table
becomes the graph's MANAGEMENT surface. The floating selection bar
gains Delete FENCED at its right end (owner-approved placement): a
divider quarantines the destructive action from Clear and Generate,
red destructive pair + trash icon, opening the SAME full-death confirm
dialog the canvas uses.

DeleteNodeDialog extended from one node to an array:
- one node renders exactly as always; many pluralize the title
  (Delete N propositions?) and list the names in the mono block,
  capped at 8 + 'and K more'
- the pre-flight impact read aggregates: summed edge counts, unioned
  referencing sessions (deduped, first-seen order); all-404 = gone
- confirm runs the per-node DELETEs SEQUENTIALLY — a failure stops
  the run (extraction_running is never plowed through); onDeleted
  now carries every id that actually died
- the chain table prunes its selection on delete and announces
  lh:graph-revision so the snapshot refetches

Drift fix found en route (surfaced as NaN in the aggregated facts):
the server's NodeDeletionImpact has been {edges, sessions} only since
the quiz-events ledger died in the practice-arc schema slim — the
dialog kept rendering quizEvents/observations as undefined. The dead
fact lines are removed; the dialog now shows exactly what the server
can honestly report.

README.md

@@ -156,7 +156,7 @@ data/                           chats/ · graph/ (six ledgers + positions/source
 
 **The knowledge graph (two channels, one writer).** The write channel: the extraction pipeline — extractor (LLM: sees only the session, rendered as readable markdown by the shared `core/session-markdown.ts` engine — propositions as true statements, `follows`/`supports` edges with verbatim evidence; fully trusted, graph-blind) → auditor (LLM, an agentic loop that never sees the source: explores the existing graph through `find` / `list_sessions` / `list_propositions` tools, stamps each proposition with an identity verdict — link to an existing node (equivalence bias: paraphrases merge) or create — and may draw bridging edges between existing nodes and the new batch) → merger (`mergeFindings`, deterministic: applies the verdicts, link-appends phrasings/provenance, resolves and dedupes edges, checkpoints coverage) → layout settle. No quiz outcomes or understanding assessments live in the graph (2026-09-27 cleanup); practice (`/practice`) consumes the graph as feedback-only problem sets and writes nothing back. Triggered when a chat's **uncovered tokens** (message-view fingerprints, `coverage.jsonl`) cross `graph.extractionChunkTokens` (a settings knob, default 4096, floor 500 — read fresh per turn); failure checkpoints nothing, the next trigger re-runs. The same pipeline serves the **notes front door** (`POST /api/graph/import`: any `*.md`/`*.txt` becomes a source; re-imports are idempotent by path hash). The read channel: `GET /api/graph` derives the snapshot from the ledgers — a pure read; the home view is a hand-rolled Canvas 2D renderer (one rAF loop, dirty-flag idle, d3-zoom camera, zoom-gated labels, cluster hulls) over a d3-force layout, with server-persisted render settings and drag-committed positions. Clusters are **birth-session groupings**: a node joins the cluster of the session that birthed it (a chat, or an imported notes file as a file-kind session), derived at read — no embedding pass, no naming pass. The teacher reaches the graph on its own terms through the gated prober tools (`list_sessions` / `list_propositions`, the `agent.graphTools` setting) — there is no automatic context injection.
 
-**Practice (problem sets).** The graph's `follows`-edges become reasoning chains; the `/practice` creation dialog picks a birth-session cluster (the graph view's own groups) and freezes its propositions + chains into a self-contained `ProblemSet`. Three named-level axes steer generation (ladder rung 0–4, cue distance 0–2, Theory|Application — never a number to interpolate; defaults Direct exercise · Adjacent context · Theory), plus an optional free-form note the agents weigh but need not follow. Creation has two entries: the cluster picker on `/practice`, or the graph view's chain table — a full-bleed sortable table of every reasoning chain, grouped by birth cluster under the shared top bar, selecting chips, chains, or whole clusters, whose floating selection bar shows the exact `N propositions → M chains` the agents will receive — handing a free-form node selection to the same dialog. A partitioner agent covers every chain exactly once, one generator per partition writes problems against the owner's problem-engineering framework (commit-before-pose: statement + solution + rubric together), and grading is **strengthening, not assessment** — one attempt per problem with its own submit button, instant solution/rubric reveal, then a score 0–10 with brief reasoning landing live; nothing ever written back to the graph. Runs are registry-backed background jobs on the activity dock (no steer, never wakes the teacher); sets live in `data/practice`, crash-swept on boot.
+**Practice (problem sets).** The graph's `follows`-edges become reasoning chains; the `/practice` creation dialog picks a birth-session cluster (the graph view's own groups) and freezes its propositions + chains into a self-contained `ProblemSet`. Three named-level axes steer generation (ladder rung 0–4, cue distance 0–2, Theory|Application — never a number to interpolate; defaults Direct exercise · Adjacent context · Theory), plus an optional free-form note the agents weigh but need not follow. Creation has two entries: the cluster picker on `/practice`, or the graph view's chain table — a full-bleed sortable table of every reasoning chain, grouped by birth cluster under the shared top bar, selecting chips, chains, or whole clusters, whose floating selection bar shows the exact `N propositions → M chains` the agents will receive — handing a free-form node selection to the same dialog — and carries the fenced Delete action, making it the graph's management view (whole-cluster cleanup through the same full-death confirm dialog). A partitioner agent covers every chain exactly once, one generator per partition writes problems against the owner's problem-engineering framework (commit-before-pose: statement + solution + rubric together), and grading is **strengthening, not assessment** — one attempt per problem with its own submit button, instant solution/rubric reveal, then a score 0–10 with brief reasoning landing live; nothing ever written back to the graph. Runs are registry-backed background jobs on the activity dock (no steer, never wakes the teacher); sets live in `data/practice`, crash-swept on boot.
 
 **Dictation.** Optional speech-to-text: the server mints short-lived Deepgram tokens; audio streams browser→Deepgram over WebSocket, never through the server.