diff --git a/.gitignore b/.gitignore
index 0ba1a3c..d2da572 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,9 +1,24 @@
 node_modules/
 dist/
 .DS_Store
+Thumbs.db
 *.log
 coverage/
 artifacts/
 playwright-report/
 .forgeflow/
 .playwright-mcp/
+.env
+.env.*
+!.env.example
+*.pfx
+*.p12
+*.key
+*.pem
+!build/update-signing-public.pem
+.codex/
+.claude/
+.agents/
+.dyad/
+.idea/
+.vs/
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..98b5667
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,13 @@
+# Contributing
+
+ForgeFlow changes must preserve exact-commit provenance, update integrity and safe deployment boundaries.
+
+Before opening a pull request:
+
+- do not commit tokens, SSH credentials, signing private keys, deployment secrets or local repository state;
+- keep update manifests/checksums/signatures deterministic and reviewable;
+- add regression tests for repository synchronization, dirty-file handling, update and deployment changes;
+- keep real deployment targets configurable rather than embedding private infrastructure;
+- run `npm run quality` and the managed validation workflow where supported.
+
+Release metadata should distinguish an unreleased package version from the latest published Gitea Release; do not advance public release claims until the corresponding release exists.
diff --git a/SECURITY.md b/SECURITY.md
index 40a8a88..e8ad22c 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -7,3 +7,5 @@ Report suspected vulnerabilities privately to the repository owner. Do not publi
 For a useful report, include the affected ForgeFlow version/commit, component, minimal reproduction steps, expected and observed behaviour and security impact. Use sanitized or synthetic repository/server data whenever possible.
 
 The current release model requires exact-commit verification, origin-constrained credential use, signed update manifests, redacted diagnostics and bounded deployment adapters. Changes must not silently weaken those guarantees.
+
+Never commit Gitea tokens, SSH private keys, release-signing private keys, deployment credentials or local repository state. The packaged signing public key is intentionally public; private signing material must remain outside Git.