diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000..5dea88b
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,7 @@
+# Project context
+
+Read these on every session. Rules in them override defaults.
+
+@ai/shared.md
+@ai/backend-context.md
+@ai/frontend-context.md
diff --git a/ai/backend-context.md b/ai/backend-context.md
new file mode 100644
index 0000000..740118b
--- /dev/null
+++ b/ai/backend-context.md
@@ -0,0 +1,105 @@
+# Backend context
+
+Read `ai/shared.md` first. This file covers backend-specific rules.
+
+## Project context
+
+**Stack:** PHP 8.4, Laravel 13, Inertia Laravel, PHPUnit, Larastan, Composer.
+
+**Location:** `backend/`.
+
+The application is still close to the Laravel starter structure. Do not
+introduce a domain architecture, repository layer, service layer, or other
+abstraction before the codebase and requested behavior justify it. Match
+existing Laravel conventions and inspect similar code before adding a new
+pattern.
+
+## Laravel patterns
+
+- Keep controllers thin. Put reusable business behavior in an appropriately
+  named application or domain class once the behavior warrants extraction.
+- Use dedicated request validation rather than validating substantial payloads
+  inline in controllers.
+- Let unexpected exceptions reach Laravel's exception handler. Catch only
+  exceptions that can be handled meaningfully at the current boundary.
+- Use Eloquent relationships and query scopes consistently rather than
+  duplicating query fragments.
+- Avoid speculative interfaces and abstractions with only one trivial
+  implementation.
+- Routes currently use Inertia, but the Vue client has not been scaffolded.
+  Do not add placeholder frontend assets as part of unrelated backend work.
+
+## Tests
+
+- Follow the existing PHPUnit organization under `tests/Unit/` and
+  `tests/Feature/`.
+- Prefer `PHPUnit\Framework\TestCase` when a test only exercises plain PHP.
+- Extend `Tests\TestCase` only when the test needs Laravel's container,
+  facades, database, routing, or HTTP kernel.
+- HTTP feature tests extend `Tests\TestCase`.
+- Use `RefreshDatabase` when a test reads or writes database state.
+- Assert behavior at the appropriate seam:
+  - Unit tests cover isolated business behavior and edge cases.
+  - Feature tests cover routing, middleware, validation, persistence, and
+    response shape.
+- Do not duplicate every business branch through the HTTP layer when unit
+  coverage already proves it. Feature tests should focus on wiring and the
+  public contract.
+
+## Test database
+
+- Development and runtime use PostgreSQL through the local Unix socket.
+- PHPUnit intentionally uses SQLite `:memory:` as configured in
+  `phpunit.xml`.
+- Feature tests are self-contained and do not require the process-compose
+  PostgreSQL service.
+- Never point `RefreshDatabase` tests at the development PostgreSQL database.
+- Keep mail set to the PHPUnit `array` transport unless a test explicitly
+  exercises a real mail integration.
+
+## PHP rules
+
+- Put imports at the top of the file. Do not use inline fully qualified class
+  names when a normal `use` statement is clearer.
+- Do not use arrow functions. Use regular anonymous functions.
+- Do not add default values to function or constructor parameters. Pass every
+  argument explicitly, including nullable arguments.
+- Use descriptive names for classes, methods, parameters, and local
+  variables.
+- Document exceptions with `@throws` when a caller is expected to handle
+  them.
+
+## Seeders
+
+- Keep `DatabaseSeeder` as the orchestrator.
+- Split substantial seed data into one seeder per domain concept and invoke
+  them in dependency order.
+- Do not add production repository or model APIs solely to make seeding
+  convenient.
+- Use existing lookup methods for cross-seeder relationships. When a group of
+  records only makes sense together, keep them in one seeder and retain local
+  references.
+
+## Migrations
+
+- Attainly is not in production yet.
+- While no production database exists, edit the original `create_*` migration
+  when changing a table instead of accumulating follow-up alter migrations.
+- Keep one migration file per table during this pre-production phase.
+- Rebuild the development database with:
+
+  ```sh
+  php artisan migrate:fresh --seed
+  ```
+
+- Once a production database exists, replace this policy with additive,
+  forward-only migrations.
+
+## Before completing backend work
+
+- Run the focused test during development.
+- Run `php artisan test` before completion.
+- Run the Composer lint and static-analysis scripts when their dependencies
+  are available.
+- Fix failures caused by the change. Report unrelated baseline failures
+  precisely rather than hiding them or expanding scope without authorization.
diff --git a/ai/frontend-context.md b/ai/frontend-context.md
new file mode 100644
index 0000000..7d9dba7
--- /dev/null
+++ b/ai/frontend-context.md
@@ -0,0 +1,90 @@
+# Frontend context
+
+Read `ai/shared.md` first. This file covers frontend-specific rules.
+
+## Current state
+
+The Vue frontend has not been scaffolded yet. The backend has Inertia Laravel
+installed and an Inertia route, but there is no `package.json`, Vue source
+tree, Vite configuration, or frontend test setup.
+
+- Do not create the frontend unless the user explicitly asks.
+- Do not invent a frontend directory, package manager, dependency version, or
+  command before the scaffold establishes it.
+- When the frontend is created, update this file with its actual paths,
+  package versions, scripts, and testing tools.
+
+## Vue conventions
+
+Apply these rules once a Vue 3 frontend exists:
+
+- Use the Composition API and `<script setup lang="ts">`.
+- Use PascalCase component filenames.
+- Keep page, component, composable, and store responsibilities distinct.
+- Prefer small components with explicit props and emitted events.
+- Keep component styles scoped unless the scaffold establishes a deliberate
+  global styling system.
+- Follow the routing and page conventions established by the chosen Inertia
+  or Vue Router scaffold. Do not mix the two approaches without an explicit
+  architectural reason.
+- Inspect similar files before introducing a new component, composable, store,
+  or data-access pattern.
+
+## TypeScript
+
+- Enable and preserve strict mode.
+- Do not use `any`. Model unknown external values as `unknown` and narrow or
+  validate them.
+- Derive types from runtime schemas when a schema library is adopted. Do not
+  maintain a hand-written type that can drift from its validation schema.
+- Validate payloads at trust boundaries, especially backend responses and
+  user-submitted forms.
+- Keep request and response types close to the API or store boundary that owns
+  them.
+- Add a path alias only when it is configured consistently in Vite,
+  TypeScript, tests, and Cypress.
+
+## State and API access
+
+- Use the state-management approach chosen by the scaffold consistently.
+- Keep server data fetching and transformation at an API/store boundary, not
+  scattered through presentation components.
+- Represent loading, empty, success, validation-error, and unexpected-error
+  states explicitly.
+- Do not cast unchecked JSON directly to an application interface.
+- Keep read and write payload types separate when their shapes differ.
+
+## Testing
+
+Use layered tests once the frontend test setup exists:
+
+- Unit tests cover pure transformations, composables, store logic, computed
+  values, and formatting.
+- Component tests cover rendering, events, form behavior, and conditional UI.
+- Cypress tests cover routing, multi-page flows, and request wiring.
+- Prefer the cheapest layer that proves the behavior.
+- Import test functions explicitly rather than relying on globals unless the
+  scaffold deliberately configures globals.
+- Build test data with small typed builders instead of repeated bare object
+  literals.
+
+## Frontend/backend test boundary
+
+- Mock backend requests in frontend tests.
+- A frontend test should verify how the UI consumes a response and which
+  request it sends, not retest Laravel's business rules.
+- Test backend persistence, validation, authentication, and mail behavior in
+  PHPUnit.
+- Keep mocked response bodies typed against the frontend's exported API or
+  store types.
+- When runtime schemas exist, parse mock-builder output through the same
+  schema so drift fails at the test boundary.
+
+## Before completing frontend work
+
+- Run the formatter, linter, type checker, unit tests, and Cypress scripts
+  defined by the frontend's `package.json`.
+- Do not substitute a hand-picked subset for the repository's eventual full
+  frontend gate.
+- If the frontend cannot run because the scaffold or a required service is
+  absent, report the precise environmental or baseline failure.
diff --git a/ai/shared.md b/ai/shared.md
new file mode 100644
index 0000000..82bf820
--- /dev/null
+++ b/ai/shared.md
@@ -0,0 +1,177 @@
+# Shared rules
+
+Rules that apply to both backend and frontend work in this repository.
+Stack-specific guides (`backend-context.md`, `frontend-context.md`) extend
+these rules.
+
+## Project state
+
+- Attainly is in early development.
+- Attainly helps users break hierarchical goals into scheduled assignments,
+  complete daily work, and track progress toward a target date.
+- Schedule recalculation must preserve completed work while redistributing
+  unfinished assignments across the remaining dates.
+- Planned features in `README.md` are future ideas, not authorized scope.
+- The Laravel backend exists under `backend/`.
+- The Vue frontend has not been scaffolded yet. Do not create it unless the
+  user explicitly asks for that work.
+- PostgreSQL is the development and runtime database.
+- PHPUnit uses in-memory SQLite for isolated tests.
+
+## Process (TDD)
+
+0. Before editing any file, ensure you are working in a dedicated git
+   worktree, not the main checkout (`git status` and `git worktree list`).
+   If on `master`/`main` or in the main working directory, create a worktree
+   first (see Branching).
+1. Write the test first.
+2. Run the test to confirm it fails for the expected reason.
+3. Commit the failing test. The test commit must precede the implementation
+   commit, not merely appear earlier in the implementation diff.
+4. Implement the smallest change that makes the test pass.
+5. Run the test to confirm it passes.
+6. Commit the implementation.
+7. Repeat for each new behavior.
+
+Use judgment for changes that cannot meaningfully be test-driven, such as
+documentation-only edits or declarative environment configuration. Validate
+those changes with the most relevant parser, formatter, dry run, or check.
+
+## Running processes
+
+- The main checkout owns the canonical stack on the default ports. Assume it
+  is the user's stack. Do not start, restart, or stop it unless the user asks.
+- A worktree owns its own isolated stack. The flake shell hook assigns a
+  deterministic port offset and creates worktree-local PostgreSQL state.
+- Start a worktree stack from its root with `process-compose up`. For
+  non-interactive use, run `process-compose up -D` and stop it with
+  `process-compose down`.
+- Do not use `process-compose -t=false` for a detached stack. It can leave an
+  orphaned PostgreSQL process holding the data directory.
+- Non-interactive agent shells do not automatically load direnv. A bare
+  `process-compose`, `php artisan`, or database command from a worktree can
+  silently use default ports and target the main checkout.
+- Prefix worktree stack and database commands with `direnv exec <worktree>`.
+  Examples:
+
+  ```sh
+  direnv exec <worktree> process-compose up -D
+  direnv exec <worktree> process-compose down
+  direnv exec <worktree> php artisan migrate:fresh --seed
+  ```
+
+- Run backend commands from `backend/`, or explicitly change into it in the
+  command.
+- When a normally valid check fails because a required service is down,
+  surface the environmental failure. Do not skip the check or silently switch
+  to a different database or service.
+- PHPUnit is self-contained and uses in-memory SQLite. It does not require the
+  PostgreSQL stack unless a future test is explicitly designed as a real
+  PostgreSQL integration test.
+
+## Code style
+
+- Keep lines at or below 80 columns where practical. Do not split short,
+  readable lines unnecessarily.
+- Use explicit, descriptive variable names. Do not use single-letter or
+  unexplained abbreviated names.
+- Explore the codebase and inspect similar files before implementing a new
+  pattern.
+- Never use em dashes in code, comments, or docblocks. Use hyphens.
+- Always use braced control-statement bodies, including early returns:
+
+  ```ts
+  if (identifier === null) {
+    return null
+  }
+  ```
+
+## Git commit style
+
+- Use present-tense, imperative subjects: `add`, `create`, `wire`, `fix`,
+  `test`.
+- Keep subjects lowercase and short, normally three to six words.
+- Match patterns in the existing git history.
+- Do not add AI or tool coauthor trailers.
+- Add a body when the subject cannot explain non-obvious motivation or
+  multi-file coordination.
+- Wrap bodies at approximately 72 columns and separate them from the subject
+  with a blank line.
+
+## Git commits
+
+- Commit tests before implementation.
+- Keep one logical change per commit. A logical change may span multiple
+  files.
+- Commit each meaningful step rather than batching unrelated work.
+- Do not include drive-by formatter or linter changes. Restore them or land
+  them as a separate formatting commit.
+- If a check fails on untouched code, do not bundle an unrelated fix. Report
+  the pre-existing failure or handle it as its own explicitly scoped change.
+
+## Branching
+
+- Never implement features directly in the main checkout or on
+  `master`/`main`.
+- Use a dedicated worktree under
+  `<repo-root>/.worktrees/<branch>`.
+- Create it with:
+
+  ```sh
+  git worktree add \
+    "$(git rev-parse --show-toplevel)/.worktrees/<branch>" \
+    -b <branch>
+  ```
+
+- Use descriptive kebab-case branch names, optionally prefixed with a type
+  such as `feature/` or `fix/`.
+- Keep worktree names short, preferably no more than about 20 characters.
+  PostgreSQL Unix socket paths are limited in length.
+- Provision a fresh worktree through direnv:
+
+  ```sh
+  direnv allow <worktree>
+  direnv exec <worktree> true
+  ```
+
+- Never symlink `backend/vendor` or a future frontend's `node_modules` from
+  another checkout. Dependency paths and generated autoloaders must remain
+  worktree-local.
+
+Do not push anything. Make commits as the TDD workflow requires.
+
+## Before completing a change
+
+Run the smallest relevant checks while iterating, then run every repository
+gate affected by the change.
+
+### Backend
+
+- Run tests from `backend/` with `php artisan test`.
+- Run the Composer checks defined by `backend/composer.json` when their
+  dependencies are available:
+
+  ```sh
+  composer lint:check
+  composer types:check
+  composer test
+  ```
+
+- Do not claim a green gate when a command fails. If the failure predates the
+  change, report the precise baseline failure.
+
+### Frontend
+
+- The frontend does not exist yet. Once scaffolded, use the scripts defined in
+  its `package.json` for formatting, linting, type checking, unit tests, and
+  end-to-end tests.
+- Update `ai/frontend-context.md` when the actual scaffold, package manager,
+  and commands are known.
+
+### Environment and integration
+
+- For Nix or shell-hook changes, run `nix fmt` and `nix flake check`.
+- For service configuration changes, run `process-compose --dry-run`.
+- When a change affects runtime wiring, start the worktree's stack and verify
+  the relevant endpoint or service against that worktree.
+- If you started the stack only for validation, stop it before finishing.