docs(agents): add setup, testing, and commit conventions

AGENTS.md had no Setup, Testing, or Commit/PR sections even though the
repo has verifiable, non-obvious conventions for all three: pre-commit
hooks span three stages with no default_install_hook_types set (a plain
`pre-commit install` silently skips commit-msg/pre-push), tests/run-tests.sh
runs the full suite, and conventional-pre-commit enforces Conventional
Commits. Agents working in this repo had no way to discover these without
reading the pre-commit config and scripts directly.

AGENTS.md

@@ -7,6 +7,21 @@ This repo is the global AI development configuration repository — the authorit
 - `plugins/` — installable plugin units; each is self-contained (skills, agents, hooks, MCP servers, bundled assets); install separately via `claude plugin install <name>@holocron`
 - `providers/claude-code/` — Claude Code adapter (deployed to `~/.claude/` via `install.sh`)
 
+## Setup
+
+- Install git hooks: `pre-commit install -t pre-commit -t pre-push -t commit-msg`. `.pre-commit-config.yaml` uses all three stages and has no `default_install_hook_types` set, so a plain `pre-commit install` only wires the `pre-commit` stage and silently skips `commit-msg` (Conventional Commits check) and `pre-push` (test suite, manifest check).
+
+## Testing instructions
+
+- Run `bash tests/run-tests.sh` before considering any change done, and fix failures — it runs every `test-*.sh` script in the repo plus the bats suite (`tests/run-bats.sh`).
+- `bash tests/run-tests.sh --bats-only` runs just the bats suite.
+- The bats suite auto-initializes its submodules (`tests/bats`, `tests/test_helper/bats-support`, `tests/test_helper/bats-assert`) on first run if the `bats` binary is missing — no manual `git submodule update` needed.
+
+## Commit / PR conventions
+
+- Commit messages must follow Conventional Commits — enforced by the `conventional-pre-commit` hook at the `commit-msg` stage.
+- Pushing runs the full test suite (`tests/run-tests.sh`) and `scripts/check-manifests.sh` (validates `marketplace.json`/`plugin.json` paths resolve) via pre-push hooks — run both locally first so a failing push isn't a surprise.
+
 ## Key documents
 
 Read CONTEXT.md at the start of every session in this repo.