Rewrite AGENTS.md sentence by sentence

Rewrite the agent rules from scratch, as a newcomer would read them,
with one idea per sentence and every file name and command in
backticks. Drop the rule that models embed `models.Base`, which no
package in the repository has, and the statement that tests share
their package: nearly every test is in an external test package with
an `export_test.go` beside it. State the branch workflow in use: pull
requests target `next` and only the owner merges `next` into `main`.
Record the three snake_case JSON tags the HTTP API keeps.

Part of #190.

Model: fable-5-1

AGENTS.md

@@ -1,55 +1,64 @@
-# AGENTS.md — Rules for AI Agents
+# Rules for coding agents
 
-## Before Every Commit
+Rules for coding agents working in this repository. `CONVENTIONS.md` defines the
+architecture and `REPO_POLICIES.md` the repository standards. Both are copies of
+shared documents and are not edited here.
 
-1. **Format**: `make fmt`
+## Before every commit
-2. **Check**: `make check` — the tests and the linter, which run in Docker, and
-   the format check: all passing, zero issues
 
-Never run `go test`, `golangci-lint` or `gofmt` directly; use the `make`
+1. Run `make fmt`.
-targets.
+2. Run `make check`. It runs the tests and the linter in Docker, then the format
+   check. All three must pass with no findings.
 
-No commit lands on main with lint errors, test failures, or formatting issues.
+Never run `go test`, `golangci-lint` or `gofmt` directly. The `make` targets
+hold the flags and the Docker setup.
 
-## Code Style
+## Branches and pull requests
 
-- Follow CONVENTIONS.md exactly — it defines the architecture
+- Never commit to `main` or `next` directly. Every change is a pull request from
-- All exported types, functions, methods, and vars must have doc comments
+  a feature branch into `next`.
-- All packages must have a package doc comment
+- Only the owner merges `next` into `main`.
-- JSON tags use camelCase (not snake_case)
+- A pull request that closes an issue has the title `Description (closes #N)`.
-- No magic numbers — use named constants
+- One logical change per commit.
-- No inline error handling (`if err := ...; err != nil`) — use plain assignment
+- Commit messages are in the imperative mood and short.
-- Blank line before every `return` statement
-- Blank line separating embedded fields from regular fields in structs
-- Blank imports must have a justification comment
 
-## Git Workflow
+## Code style
 
-- **Never commit directly to main** — all changes go on feature branches
+- Follow `CONVENTIONS.md`.
-- Merge to main only when ready and passing all checks
+- Every package has a package doc comment. Every exported type, function, method
-- PR titles: `Description (closes #N)` when closing an issue
+  and variable has a doc comment.
-- One logical change per commit
+- JSON tags are camelCase. The HTTP API's `last_id`, `pow_token` and
-- Commit messages: imperative mood, concise
+  `hashcash_bits` stay as they are, each with a `//nolint:tagliatelle` comment.
+- No magic numbers. Use named constants.
+- No inline error handling such as `if err := f(); err != nil`. Assign the error
+  on its own line, then test it.
+- A blank line before every `return`.
+- A blank line between the embedded fields of a struct and its other fields.
+- Every blank import has a comment saying why it is there.
 
 ## Architecture
 
-- Dependency injection via Uber fx — all components are fx providers
+- Dependency injection uses Uber `fx`. Every component is an `fx` provider,
-- `internal/` for all application packages — one package per concern
+  wired together in `cmd/neoircd/main.go`.
-- Handlers return `http.HandlerFunc` using the closure pattern
+- Application packages live under `internal/`, one package per concern.
-- Request/response structs defined inside handler closures
+  `pkg/irc` holds the IRC command names and numeric reply codes.
-- Models embed `models.Base` for database access to relation methods
+- A handler method returns an `http.HandlerFunc`.
-- Database migrations in `internal/db/schema/` — embedded via `go:embed`
+- A request struct is defined inside the handler that decodes it.
-- SQLite by default (pure Go driver: modernc.org/sqlite)
+- Database access goes through the methods of `db.Database`.
+- The database schema lives in `internal/db/schema/` and is embedded with
+  `go:embed`.
+- The database is SQLite, through the pure Go driver `modernc.org/sqlite`.
 
 ## Testing
 
-- Table-driven tests preferred
+- Prefer table-driven tests.
-- Use `testing.T` helpers, not assertion libraries
+- Use `testing.T` helpers, not assertion libraries.
-- Test files live next to the code they test
+- A test file lives next to the code it tests and ends in `_test.go`.
-- `_test.go` suffix, same package for white-box testing
+- Tests are in the package's external test package, such as `handlers_test`. An
+  `export_test.go` file in the package itself exposes what the tests need.
 
 ## Dependencies
 
-- Required libraries are listed in CONVENTIONS.md §1
+- The required libraries are listed in `CONVENTIONS.md` §1.
-- No new dependencies without justification
+- No new dependency without a reason given in the pull request.
-- Pure Go preferred (no CGO)
+- Prefer pure Go. No cgo.