Recall

A memory engine for your LeetCode practice. Paste the Problem Log summary from your Claude tutoring session; Recall parses it, derives a review grade from how the solve actually went, schedules spaced-repetition reviews with FSRS, and mirrors due dates onto your calendar.

Run it

npm install
npm run db:push        # create/update the SQLite schema (data/recall.db)
npm run import:sheet   # one-time: seed from the DSA Google Sheet history
npm run dev            # http://localhost:3000

Daily loop

1. Solve a problem with your Claude tutor (the tutor Skill ends the session with a Problem Log summary).
2. Log → paste → Parse → confirm → Save. (~15 seconds)
3. Each morning, Today shows what's due. Each review is a 2-minute approach recall: name the pattern, state the invariant, give the complexity — then reveal and grade yourself honestly.

The Problem Log template

Anything close to this parses perfectly (free-form text also works, best-effort; set ANTHROPIC_API_KEY to parse messy summaries with Claude):

## Problem Log — 49. Group Anagrams
URL / Difficulty / Patterns: https://leetcode.com/problems/group-anagrams/ · Medium · arrays-hashing
Solved: with 2 hints     Recall speed: slow
Confidence: before 2/5 → after 3/5     Time: approach 12 min · code 20 min
Fundamentals missing: definition of anagram
Issues: wrong pattern; code was messy
Brute force: compare every pair — O(n²k) / O(1)
Optimal: bucket by sorted-string key — O(nk log k) / O(nk)
Key insight: all anagrams share one canonical form
Tips: char-count tuple avoids the sort
Revise: yes — pattern recognition still weak
Suggested grade: hard — needed hints for the invariant

Grades: again (couldn't do it) · hard (hints/slow/low confidence) · good (solo with friction) · easy (instant + optimal). The tutor's suggested grade wins; otherwise Recall derives it from the signals.

Calendar

Subscribe once in Google Calendar: Other calendars → From URL → http://<host>:3000/api/calendar/dev.ics (set CALENDAR_TOKEN to change the secret). Overdue reviews appear on today. Note: Google only refreshes subscribed feeds every 12–24h, which is fine for multi-day intervals; Apple Calendar refreshes faster. While the app only runs on localhost the feed can't be reached by Google's servers — use the in-app Today queue as primary (it is anyway), or deploy first.

MCP — let the tutoring chat log problems itself

Recall is also an MCP server at /api/mcp (tools: add_problem, get_due_reviews, log_review, get_stats). With the dev server running, connect Claude Code:

claude mcp add --transport http recall http://localhost:3000/api/mcp --header "Authorization: Bearer dev"

(Replace dev if you set MCP_TOKEN.) Then at the end of a tutoring session, say "log it" — Claude calls add_problem directly, zero copy-paste. For claude.ai custom connectors the endpoint must be publicly reachable, i.e. after deployment.

The tutor prompt in docs/tutor-prompt.md is written to use these tools when available and fall back to the paste template otherwise.

Insights

/insights — activity heatmap, felt-vs-actual calibration (fed by the review player's pre-reveal confidence slider), confidence trend, per-pattern mastery, and grade distribution. Sparse until you've logged a few weeks of reviews.

Environment (.env)

Variable	Default	Purpose
DATABASE_PATH	data/recall.db	SQLite location
CALENDAR_TOKEN	dev	Secret in the ICS feed URL
ANTHROPIC_API_KEY	—	Enables AI parsing of free-form summaries
PARSE_MODEL	Haiku 4.5	Model for AI parsing
MCP_TOKEN	dev	Bearer token for the MCP endpoint
RECALL_USER_ID	shreet	Row owner (multi-user later)

Deploy (Vercel + Turso)

The app runs on local SQLite with zero setup; setting TURSO_DATABASE_URL switches it to Turso (hosted libSQL — same schema, same queries). Deployed instances should also set APP_PASSWORD, which activates the login gate on every page and API (the MCP endpoint and ICS feed keep their own tokens).

One-time, interactive (browser OAuth — only steps a human can do):

turso auth signup

npx vercel login

Then, from recall/:

1. sqlite3 data/recall.db "PRAGMA wal_checkpoint(TRUNCATE);" then turso db create recall --from-file data/recall.db — creates the cloud DB with all existing data.
2. turso db show recall --url and turso db tokens create recall → the two TURSO_* values.
3. npx vercel link, add env vars (TURSO_DATABASE_URL, TURSO_AUTH_TOKEN, APP_PASSWORD, CALENDAR_TOKEN, MCP_TOKEN, optionally ANTHROPIC_API_KEY), then npx vercel --prod.

After deploy:

• Calendar: Google Calendar → Other calendars → From URL → https://<app>.vercel.app/api/calendar/<CALENDAR_TOKEN>.ics (now reachable by Google's servers, so it actually syncs).
• MCP from claude.ai: Settings → Connectors → Add custom connector → https://<app>.vercel.app/api/mcp with header Authorization: Bearer <MCP_TOKEN>.
• Note: local SQLite and Turso are now separate databases. Treat the deployed app as the source of truth; for cloud-backed local dev, put the TURSO_* values in .env.

Architecture notes

• Next.js 16 App Router · Tailwind v4 + shadcn/ui (Base UI) · Drizzle + better-sqlite3 · ts-fsrs (FSRS-6, long-term mode, retention 0.9, max interval 365d, first interval floored at 2 days).
• Every table carries user_id so multi-user (Supabase/Postgres + auth) is a migration, not a rewrite.
• A re-solve of an existing problem (same slug) logs a review against the existing record — never a duplicate row.
• Roadmap: concept-level scheduling (a fundamentals table that schedules the skill, not just the problem); sibling-problem substitution on mature cards; deployment (Vercel + Supabase) so the calendar feed and claude.ai connector work from anywhere.