chore: remove Lean spec; ADRs are the single source of truth

The spec/ Lean semantic master had no conformance gate, no codegen, and
no CI tie to implementations — alignment was carried entirely by human
review, the same mechanism that carries the ADRs. In practice the ADRs
plus greppable code comments were already the load-bearing artifacts,
so spec/ was the most expensive kind of stale documentation.

- delete spec/ and the spec-check CI workflow
- README: constitution rewritten around ADRs as decision truth
- AGENTS.md/CLAUDE.md: discipline re-anchored (new decisions -> new ADR,
  never rewrite ADR history; supersede instead)
- code comments: re-anchor 'Mirrors Spec.X' invariants to ADR numbers
  (cph-diag, cph-check, cph-model, hub runner/capacity/org, prisma)
- leave ADR bodies and .scratch audit snapshots untouched (history);
  fix live references in open readiness tickets

hub/package.json

@@ -30,7 +30,7 @@
       "axios": "1.18.1"
     }
   },
-  "description": "Curriculum Project Hub — org-scoped Feishu collaboration and confined Agent runtime. Aligns to spec/System through ADR-0024.",
+  "description": "Curriculum Project Hub — org-scoped Feishu collaboration and confined Agent runtime. Semantics pinned by docs/adr/ (ADR-0001 through ADR-0027).",
   "scripts": {
     "dev": "npm run prisma:migrate && tsx watch src/server.ts",
     "build": "tsc -p tsconfig.json && npm run admin:build",

hub/prisma/migrations/20260714120000_drop_legacy_platform_role_assignment/migration.sql

@@ -1,6 +1,6 @@
 -- ADR-0023 rejected the legacy `PlatformRoleAssignment` / `PlatformRole`{ADMIN,TEACHER}
 -- model: the platform administration control plane is a separate identity/session/
--- audit surface (see `Spec.System.PlatformAdministration`), intentionally not built
+-- audit surface, intentionally not built
 -- in alpha (ADR-0025, `hub/deploy/README.md`). The legacy table has no runtime
 -- reader — no guard, route, or service queries it for an authorization decision —
 -- and ADR-0023 requires it to be migrated/replaced before the platform panel ships.

hub/prisma/schema.prisma

@@ -1,6 +1,6 @@
 // Prisma schema for Curriculum Project Hub.
 //
-// Aligns to spec/System (ADR-0001..0004, 0017). Key divergences from the
+// Aligns to ADR-0001..0004, 0017. Key divergences from the
 // legacy teaching-material-host-service schema, each deliberate:
 //
 //  - AgentSession is provider/model-bound. Provider runtime cursors such as
@@ -11,8 +11,8 @@
 //  - ProjectGroupBinding is project→chat only (ADR-0001 1:1); legacy mixed
 //    user/chat targets into one binding table.
 //  - PermissionGrant + PermissionSettings land (ADR-0004), missing in legacy.
-//  - AgentRunStatus adds WAITING_FOR_USER + TIMED_OUT (spec RunState; enum
-//    completeness OPEN — add states without a schema migration war).
+//  - AgentRunStatus adds WAITING_FOR_USER + TIMED_OUT (the run-state set is
+//    open — add states without a schema migration war).
 
 generator client {
   provider = "prisma-client-js"
@@ -61,7 +61,7 @@ enum OrganizationStatus {
 }
 
 /// Org-scoped membership role. Distinct from project PermissionRole and from
-/// the platform administrator surface (ADR-0023 / Spec.System.PlatformAdministration),
+/// the platform administrator surface (ADR-0023),
 /// which is a separate control plane not modeled in alpha (ADR-0025).
 model OrganizationMembership {
   id             String                 @id @default(cuid())

hub/src/agent/runner.ts

@@ -24,10 +24,10 @@
  * denied by default and re-opened only for the workspace plus named system
  * runtimes, and `failIfUnavailable` hard-fails if the sandbox can't start. The
  * subprocess gets a minimal environment and SDK credential protection removes
- * provider secrets from Bash. This upholds `AgentFileOp.Authorized`
- * (ADR-0018 / `Spec.System.AgentSurface`) without re-implementing the
+ * provider secrets from Bash. This upholds the workspace-bounded file-op
+ * invariant (ADR-0018) without re-implementing the
  * `workspace.ts` `confine()` path validator as a tool wrapper — the OS sandbox
- * is the mechanism, the contract pins the invariant.
+ * is the mechanism, the ADR pins the invariant.
  */
 import { query, type HookCallback, type McpServerConfig, type SDKMessage, type SDKAssistantMessage, type SDKUserMessage, type SDKResultMessage, type SDKPartialAssistantMessage, type SDKSystemMessage } from "@anthropic-ai/claude-agent-sdk";
 import type { PrismaClient } from "@prisma/client";

hub/src/capacity/dimensions.ts

@@ -1,6 +1,6 @@
 /**
- * ADR-0022 capacity dimensions (spec `Spec.System.Capacity.CapacityDimension`).
- * The 23 PINNED dimensions; exact numeric ceilings are `OPEN` and calibrated by
+ * ADR-0022 capacity dimensions.
+ * The 23 pinned dimensions; exact numeric ceilings are open and calibrated by
  * capacity testing. This module is the single source of the dimension set shared
  * by the platform-ceiling config and the org capacity-policy service.
  */

hub/src/org/capacityPolicy.ts

@@ -1,9 +1,9 @@
 /**
- * Org capacity policy service (ADR-0022 / spec `Spec.System.Capacity`).
+ * Org capacity policy service (ADR-0022).
  *
  * Stores per-Organization lower `organizationLimit` overrides per
- * `CapacityDimension`. Enforces `LayeredLimit.Valid`: a set limit must be ≤ the
- * platform ceiling for that dimension. `LayeredLimit.effective` (min of the two)
+ * `CapacityDimension`. Enforces the layered-limit invariant: a set limit must be ≤ the
+ * platform ceiling for that dimension. The effective limit (min of the two)
  * is the value capacity admission should use; dimensions with no org override
  * fall back to the platform ceiling.
  */

hub/src/org/members.ts

@@ -1,7 +1,7 @@
 /**
  * Organization membership management for org admin (ADR-0021).
  *
- * Role rules (product pin, not yet in Lean):
+ * Role rules (product pin, not yet recorded in an ADR):
  * 1. Actor must be OWNER or ADMIN (enforced at HTTP layer).
  * 2. Only OWNER can grant/revoke OWNER or modify another OWNER.
  * 3. Cannot revoke or demote the last remaining OWNER.