diff --git a/AGENTS.md b/AGENTS.md
index 31a13f1c..c848926e 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -34,3 +34,25 @@ The files below are the shared source of truth for path-specific guidance. Claud
 - `.claude/rules/database.md`: migration rules, key tables/RPCs/triggers, pg-real (`supabase/migrations/**`)
 - `.claude/rules/mcp-server.md`: MCP tool authoring, staged-operation pattern, OAuth 2.1 connector auth
 - `.claude/rules/bookkeeping.md`: BAS accounts, VAT treatments/rutor, `lib/core/` services
+
+
+## SIAX toolchain-kontrakt (2026-09-15, W4-slutvåg)
+
+- `mise.toml` = task-entry (`setup/check/verify/build/release`) — genererad ur
+  toolchain-discovery (observerade data). Ändra inte betydelsen av de fem tasks.
+- Package manager: **npm**.
+- `lefthook.yml` = git hooks; aktiveras med `npx lefthook install`.
+- Pinning: `.siax/template-pin.json` (`siax.template-pin/v1`).
+- Förbjudna duplicater: just/Task/Nx, Cypress, OpenProject/Leantime/AppFlowy,
+  Keycloak, SigNoz.
+- Not: gaterna heter check:types/check:lint.
+
+### Snabbkommandon
+
+```sh
+mise install
+mise run setup        # npm ci --no-audit --no-fund
+mise run check
+mise run verify
+mise run build
+```
diff --git a/README.md b/README.md
index fd3cb800..b4d4cd3c 100644
--- a/README.md
+++ b/README.md
@@ -96,3 +96,25 @@ All commits require a [DCO sign-off](DCO) (`git commit -s`).
 ## License
 
 [AGPL-3.0-or-later](LICENSE) with an **extension exception**: third-party extensions that interact solely through the documented Extension API may be licensed under any terms, including proprietary. See [LICENSE](LICENSE) for details and [NOTICE](NOTICE) for third-party attributions.
+
+
+## SIAX toolchain-kontrakt (2026-09-15, W4-slutvåg)
+
+- `mise.toml` = task-entry (`setup/check/verify/build/release`) — genererad ur
+  toolchain-discovery (observerade data). Ändra inte betydelsen av de fem tasks.
+- Package manager: **npm**.
+- `lefthook.yml` = git hooks; aktiveras med `npx lefthook install`.
+- Pinning: `.siax/template-pin.json` (`siax.template-pin/v1`).
+- Förbjudna duplicater: just/Task/Nx, Cypress, OpenProject/Leantime/AppFlowy,
+  Keycloak, SigNoz.
+- Not: gaterna heter check:types/check:lint.
+
+### Snabbkommandon
+
+```sh
+mise install
+mise run setup        # npm ci --no-audit --no-fund
+mise run check
+mise run verify
+mise run build
+```