diff --git a/.siax/template-pin.json b/.siax/template-pin.json
new file mode 100644
index 00000000..3f209a78
--- /dev/null
+++ b/.siax/template-pin.json
@@ -0,0 +1,17 @@
+{
+  "schemaVersion": "siax.template-pin/v1",
+  "repo": "accounted",
+  "profiles": [
+    "base",
+    "node"
+  ],
+  "templateRepo": "sax3l/siax-templates",
+  "templateRef": "1feb97cd1d6da58bb4b420d860109285c47c741d",
+  "pinnedAt": "2026-09-15T02:40:00Z",
+  "pins": {
+    "mise": "task-entry i mise.toml (repot rot)",
+    "node": "22",
+    "lefthook": "1.x (aktiveras med npx lefthook install)"
+  },
+  "notes": "Genererad ur toolchain-discovery 2026-09-15 (siax-automation)."
+}
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
+```
diff --git a/lefthook.yml b/lefthook.yml
new file mode 100644
index 00000000..caacb303
--- /dev/null
+++ b/lefthook.yml
@@ -0,0 +1,14 @@
+# SIAX toolchain-kontrakt v0.1.0 — Lefthook för accounted.
+# Aktiveras med: npx lefthook install. Hook-skip ersätter aldrig CI-gates.
+
+pre-commit:
+  parallel: true
+  commands:
+    check:
+      run: mise run check
+
+pre-push:
+  parallel: false
+  commands:
+    verify:
+      run: mise run verify
diff --git a/mise.toml b/mise.toml
new file mode 100644
index 00000000..55282f51
--- /dev/null
+++ b/mise.toml
@@ -0,0 +1,36 @@
+# SIAX toolchain-kontrakt v0.1.0 (sax3l/siax-templates @ SHA-pinad i
+# .siax/template-pin.json) — accounted-instans. Genererad ur toolchain-discovery
+# (observerade data: packageManager + CI-enforced scripts, 2026-09-15).
+# mise är task-ENTRY; gate-logiken bor i .gitea/workflows/ (repots egen CI).
+
+[tools]
+node = "22"
+[tasks.setup]
+description = "Installera beroenden (frozen lockfile)"
+run = "set -eu; npm ci --no-audit --no-fund"
+
+[tasks.check]
+description = "Snabba deterministiska kontroller (spegler CI-enforced gates)"
+run = '''
+set -eu
+
+'''
+
+[tasks.verify]
+description = "Full svit enligt repots egna scripts"
+run = '''
+set -eu
+npm run test
+'''
+
+[tasks.build]
+description = "Bygg (repots build-script)"
+run = "set -eu; npm run build"
+
+[tasks.release]
+description = "Verifiera innan release; deploy/release-vägen ägs av repots egna workflows"
+run = '''
+set -eu
+npm run test
+echo "Release-vägen: .gitea/workflows/ äger deployen. Byt aldrig förbi approval." >&2
+'''