fix: align compaction cuts and native usage accounting

docs/development.md

@@ -30,7 +30,6 @@ npm run desktop:dist   # local signed/notarized macOS arm64 build (LH_NOTARY key
 npx tsx --env-file=.env.local scripts/import-notes.ts <dir>   # bulk-import notes → graph
 npx tsx --env-file=.env.local scripts/backfill-graph.ts       # wipe + re-extract every chat
 npx tsx --env-file=.env.local scripts/replay-layout.ts        # re-derive layout from the ledgers
-npx tsx scripts/sync-pricing.ts                               # regenerate core/prices.ts tables
 ```
 
 For Windows/Linux packages and the three-OS CI/release flow, see [`desktop-release.md`](desktop-release.md). Native renderer binaries are traced per platform, so release builds run on the target OS, not as cross-builds from macOS.
@@ -144,7 +143,7 @@ src/
 electron/                       desktop launcher + security guard (spawns the standalone
                                 server; 1 IPC channel; LH_DATA_DIR + BYOK env)
 scripts/                        build-server.mjs (packaging guards), import-notes,
-                                backfill-graph, replay-layout, sync-pricing
+                                backfill-graph, replay-layout
 data/                           chats/ · graph/ (nodes/chains/sessions/coverage
                                 ledgers + positions/sources/render-settings maps) ·
                                 jobs/ · settings.json — runtime state, git-ignored
@@ -152,6 +151,10 @@ data/                           chats/ · graph/ (nodes/chains/sessions/coverage
 
 ## Key mechanisms
 
+See [compaction and accounting](compaction-accounting.md) for the local Pi cutoff port,
+measurement-only context meter, and server-side current-catalog pricing. There is no
+pricing-generation step: Pi AI's catalog and public calculator are the authority.
+
 **Client-side question tools.** `quiz` and `ask_user_question` have no server `execute`: the tool call streams to the browser, the learner answers in the dock, the client grades via `question-core` and returns the verdict with `addToolOutput` — which fires the SDK continuation so the teacher resumes mid-turn. Options are shuffled deterministically (seeded by toolCallId) so server and client renders match. A pending quiz persisted in the chat record is exactly what makes **resume mid-question free**.
 
 **The formal plan tree (author-once).** The teacher authors the session's dependency tree with one schema-validated tool — `plan_init`, whose mermaid-subset input is parsed deterministically (line-numbered errors) and validated as a DAG. The tree persists in the chat record; progress is never mutated — `current`/`visited`/upcoming are **derived** from tagged quiz calls in the transcript, and the panel renders that derivation.