feat(session-planner): integrate SessionMode for single source of truth targeting

The session planner now accepts an optional sessionMode parameter that:
- Uses pre-computed weak skills from SessionMode (remediation mode)
- Eliminates duplicate BKT computation between UI and problem generation
- Ensures "no rug-pulling" - what the modal shows is what configures problems

Changes:
- session-planner.ts: Accept sessionMode, use getWeakSkillIds() when provided
- useSessionPlan.ts: Accept sessionMode in generateSessionPlan function
- plans/route.ts: Pass sessionMode from request body to planner
- StartPracticeModal.tsx: Pass sessionMode when generating plan
- index.ts: Export SessionMode types from curriculum module

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/web/src/app/api/curriculum/[playerId]/sessions/plans/route.ts

@@ -9,6 +9,7 @@ import {
   NoSkillsEnabledError,
 } from '@/lib/curriculum'
 import type { ProblemGenerationMode } from '@/lib/curriculum/config'
+import type { SessionMode } from '@/lib/curriculum/session-mode'
 
 interface RouteParams {
   params: Promise<{ playerId: string }>
@@ -74,6 +75,7 @@ export async function POST(request: NextRequest, { params }: RouteParams) {
       enabledParts,
       problemGenerationMode,
       confidenceThreshold,
+      sessionMode,
     } = body
 
     if (!durationMinutes || typeof durationMinutes !== 'number') {
@@ -102,6 +104,8 @@ export async function POST(request: NextRequest, { params }: RouteParams) {
       // Pass BKT confidence threshold if specified
       confidenceThreshold:
         typeof confidenceThreshold === 'number' ? confidenceThreshold : undefined,
+      // Pass session mode for single source of truth targeting
+      sessionMode: sessionMode as SessionMode | undefined,
       // Pass config overrides if abacusTermCount is specified
       ...(abacusTermCount && {
         config: {

apps/web/src/components/practice/StartPracticeModal.tsx

@@ -211,6 +211,8 @@ export function StartPracticeModal({
             abacusTermCount: { min: 3, max: abacusMaxTerms },
             enabledParts,
             problemGenerationMode: 'adaptive-bkt',
+            // Pass sessionMode for single source of truth targeting (no rug-pulling)
+            sessionMode,
           })
         } catch (err) {
           if (err instanceof ActiveSessionExistsClientError) {
@@ -235,6 +237,7 @@ export function StartPracticeModal({
     abacusMaxTerms,
     enabledParts,
     existingPlan,
+    sessionMode,
     generatePlan,
     approvePlan,
     startPlan,

apps/web/src/hooks/useSessionPlan.ts

@@ -3,6 +3,7 @@
 import { useMutation, useQuery, useQueryClient, useSuspenseQuery } from '@tanstack/react-query'
 import type { SessionPlan, SlotResult } from '@/db/schema/session-plans'
 import type { ProblemGenerationMode } from '@/lib/curriculum/config'
+import type { SessionMode } from '@/lib/curriculum/session-mode'
 import { api } from '@/lib/queryClient'
 import { sessionPlanKeys } from '@/lib/queryKeys'
 
@@ -57,6 +58,7 @@ async function generateSessionPlan({
   enabledParts,
   problemGenerationMode,
   confidenceThreshold,
+  sessionMode,
 }: {
   playerId: string
   durationMinutes: number
@@ -68,6 +70,8 @@ async function generateSessionPlan({
   problemGenerationMode?: ProblemGenerationMode
   /** BKT confidence threshold for identifying struggling skills */
   confidenceThreshold?: number
+  /** Pre-computed session mode for targeting consistency */
+  sessionMode?: SessionMode
 }): Promise<SessionPlan> {
   const res = await api(`curriculum/${playerId}/sessions/plans`, {
     method: 'POST',
@@ -78,6 +82,7 @@ async function generateSessionPlan({
       enabledParts,
       problemGenerationMode,
       confidenceThreshold,
+      sessionMode,
     }),
   })
   if (!res.ok) {

apps/web/src/lib/curriculum/index.ts

@@ -36,18 +36,14 @@ export {
   // Skill mastery
   calculateMasteryPercent,
   // Practice sessions
-  completePracticeSession,
   getAllSkillMastery,
   getPlayerCurriculum,
   getPlayerProgressSummary,
   getRecentSessions,
-  getSessionsForPhase,
   getSkillMastery,
   initializeStudent,
   recordSkillAttempt,
   recordSkillAttempts,
-  startPracticeSession,
-  updatePracticeSession,
   upsertPlayerCurriculum,
 } from './progress-manager'
 
@@ -66,3 +62,18 @@ export {
   recordSlotResult,
   startSessionPlan,
 } from './session-planner'
+
+// Session mode - unified session state computation
+export {
+  getSessionMode,
+  getWeakSkillIds,
+  isMaintenanceMode,
+  isProgressionMode,
+  isRemediationMode,
+  type BlockedPromotion,
+  type MaintenanceMode,
+  type ProgressionMode,
+  type RemediationMode,
+  type SessionMode,
+  type SkillInfo,
+} from './session-mode'

apps/web/src/lib/curriculum/session-planner.ts

@@ -58,6 +58,7 @@ import {
   getRecentSessions,
   recordSkillAttemptsWithHelp,
 } from './progress-manager'
+import { getWeakSkillIds, type SessionMode } from './session-mode'
 
 // ============================================================================
 // Plan Generation
@@ -90,6 +91,12 @@ export interface GenerateSessionPlanOptions {
    * - 'classic': Fluency-based discrete states
    */
   problemGenerationMode?: ProblemGenerationMode
+  /**
+   * Pre-computed session mode from getSessionMode().
+   * When provided, skips duplicate BKT computation and uses the mode's weak skills directly.
+   * This ensures the session targets exactly what was shown in the UI (no "rug-pulling").
+   */
+  sessionMode?: SessionMode
 }
 
 /**
@@ -136,6 +143,7 @@ export async function generateSessionPlan(
     config: configOverrides,
     enabledParts,
     problemGenerationMode = DEFAULT_PROBLEM_GENERATION_MODE,
+    sessionMode,
   } = options
 
   const config = { ...DEFAULT_PLAN_CONFIG, ...configOverrides }
@@ -248,11 +256,25 @@ export async function generateSessionPlan(
   const struggling = findStrugglingSkills(skillMastery)
   const needsReview = findSkillsNeedingReview(skillMastery, config.reviewIntervalDays)
 
-  // Identify weak skills from BKT for targeting (adaptive modes only)
-  const weakSkills = usesBktTargeting ? identifyWeakSkills(bktResults) : []
+  // Identify weak skills for targeting
+  // When sessionMode is provided, use its pre-computed weak skills (single source of truth)
+  // This ensures the session targets exactly what was shown in the UI (no "rug-pulling")
+  let weakSkills: string[]
+  if (sessionMode) {
+    // Use pre-computed weak skills from sessionMode
+    weakSkills = getWeakSkillIds(sessionMode)
+    if (process.env.DEBUG_SESSION_PLANNER === 'true') {
+      console.log(
+        `[SessionPlanner] Using weak skills from sessionMode (${sessionMode.type}): ${weakSkills.length}`
+      )
+    }
+  } else {
+    // Fallback: compute locally (for backwards compatibility)
+    weakSkills = usesBktTargeting ? identifyWeakSkills(bktResults) : []
+  }
 
   if (process.env.DEBUG_SESSION_PLANNER === 'true' && weakSkills.length > 0) {
-    console.log(`[SessionPlanner] Identified ${weakSkills.length} weak skills for targeting:`)
+    console.log(`[SessionPlanner] Targeting ${weakSkills.length} weak skills:`)
     for (const skillId of weakSkills) {
       const bkt = bktResults?.get(skillId)
       console.log(`  ${skillId}: pKnown=${(bkt?.pKnown ?? 0 * 100).toFixed(0)}%`)