diff --git a/CHANGELOG.md b/CHANGELOG.md
index 927a027..6c2060b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ Please choose versions by [Semantic Versioning](http://semver.org/).
 
 ## Unreleased
 
+- feat(rules): add four `### RULE` blocks to `docs/go-security-linting.md` — `go-security/file-perms-too-permissive`, `go-security/dir-perms-too-permissive`, `go-security/nosec-requires-reason`, `go-security/chmod-return-checked`; matching ast-grep YAMLs + `rules/index.json` entries
 - chore(release): live-verify `github-releaser-agent` plugin-manifest bumping — release commit should rewrite `.claude-plugin/plugin.json` + `.claude-plugin/marketplace.json` version fields alongside the CHANGELOG (feature shipped via `bborbe/maintainer` PR #33).
 
 ## v0.11.0
diff --git a/docs/go-security-linting.md b/docs/go-security-linting.md
index 34e358c..4bf8fae 100644
--- a/docs/go-security-linting.md
+++ b/docs/go-security-linting.md
@@ -54,3 +54,87 @@ cmd := exec.CommandContext(ctx, "git", "push")
 - [ ] All `#nosec` have explanatory comments
 - [ ] All `os.Chmod` return values checked (or explicitly `_ =` with comment)
 - [ ] No `os.ReadFile` with untrusted paths without `#nosec` + reason
+
+### RULE go-security/file-perms-too-permissive (MUST)
+
+**Owner**: go-security-specialist
+**Applies when**: `os.WriteFile($PATH, $DATA, $PERM)` or `os.OpenFile($PATH, $FLAGS, $PERM)` calls in a `*.go` file outside `*_test.go` and `vendor/`, where `$PERM` is a literal octal that is NOT `0600` / `0o600`.
+**Enforcement**: `rules/go/file-perms-too-permissive.yml`
+**Why**: world-readable file permissions (e.g. `0644`) expose configuration data, lock files, and other artifacts to any process on the host. gosec G306 flags this; the convention is owner-only `0600` for ALL files unless there is a specific reason documented via `#nosec` with explanation.
+
+#### Bad
+
+```go
+os.WriteFile(path, data, 0644)
+os.OpenFile(path, os.O_CREATE|os.O_WRONLY, 0644)
+```
+
+#### Good
+
+```go
+os.WriteFile(path, data, 0600)
+os.OpenFile(path, os.O_CREATE|os.O_WRONLY, 0600)
+```
+
+### RULE go-security/dir-perms-too-permissive (MUST)
+
+**Owner**: go-security-specialist
+**Applies when**: `os.MkdirAll($PATH, $PERM)` or `os.Mkdir($PATH, $PERM)` calls in a `*.go` file outside `*_test.go` and `vendor/`, where `$PERM` is a literal octal that is NOT `0750` / `0o750`.
+**Enforcement**: `rules/go/dir-perms-too-permissive.yml`
+**Why**: world-readable directories (e.g. `0755`) expose contents to any process on the host. The convention is `0750` (owner-rwx + group-rx, no world) for ALL agent-created directories.
+
+#### Bad
+
+```go
+os.MkdirAll(dir, 0755)
+os.Mkdir(dir, 0755)
+```
+
+#### Good
+
+```go
+os.MkdirAll(dir, 0750)
+os.Mkdir(dir, 0750)
+```
+
+### RULE go-security/nosec-requires-reason (MUST)
+
+**Owner**: go-security-specialist
+**Applies when**: a `// #nosec <CODE>` comment in a `*.go` file outside `*_test.go` and `vendor/` appears WITHOUT a `-- <reason>` text component on the same line.
+**Enforcement**: `rules/go/nosec-requires-reason.yml`
+**Why**: bare `#nosec` suppresses a finding without explaining why the input is trusted. The next reviewer has no audit trail. Mandate `// #nosec G304 -- path from internal ListQueued(), not user input` style.
+
+#### Bad
+
+```go
+// #nosec G304
+data, err := os.ReadFile(userPath)
+```
+
+#### Good
+
+```go
+// #nosec G304 -- path from internal ListQueued(), not user input
+data, err := os.ReadFile(trustedPath)
+```
+
+### RULE go-security/chmod-return-checked (MUST)
+
+**Owner**: go-security-specialist
+**Applies when**: an `os.Chmod($PATH, $PERM)` call in a `*.go` file outside `*_test.go` and `vendor/` whose return value is discarded (no `if err := os.Chmod(...); err != nil` wrapper, no `_ = os.Chmod(...)` with an explanatory comment). Detecting "return value used in error check" requires reading the surrounding statement — pure ast-grep cannot reliably distinguish a checked `os.Chmod(...)` from an unchecked one without false positives.
+**Enforcement**: judgment
+**Why**: silent `os.Chmod` failures leave file permissions in an unexpected state. The convention is either `if err := os.Chmod(...); err != nil { return ... }` or explicit `_ = os.Chmod(...)` with a comment explaining why the error is ignored.
+
+#### Bad
+
+```go
+os.Chmod(path, 0600)
+```
+
+#### Good
+
+```go
+if err := os.Chmod(path, 0600); err != nil {
+    return errors.Wrapf(ctx, err, "chmod %s", path)
+}
+```
diff --git a/prompts/completed/008-bootstrap-rules-go-security-linting.md b/prompts/completed/008-bootstrap-rules-go-security-linting.md
new file mode 100644
index 0000000..4e261d8
--- /dev/null
+++ b/prompts/completed/008-bootstrap-rules-go-security-linting.md
@@ -0,0 +1,262 @@
+---
+status: completed
+summary: 'Migrated docs/go-security-linting.md from prose-only to rule-blocks-inline: appended four ### RULE blocks (3 mechanical + 1 judgment), created three ast-grep YAML detectors, ran make build-index to grow rules/index.json from 9 to 13 entries, and added ## Unreleased to CHANGELOG.md.'
+container: coding-bootstrap-go-security-exec-008-bootstrap-rules-go-security-linting
+dark-factory-version: v0.173.0
+created: "2026-06-01T19:53:46Z"
+queued: "2026-06-01T19:57:23Z"
+started: "2026-06-01T19:57:29Z"
+completed: "2026-06-01T19:59:55Z"
+---
+
+<summary>
+- Third bootstrap prompt — migrates `docs/go-security-linting.md` from prose-only to rule-blocks-inline (Model A)
+- Appends 4 `### RULE` blocks (3 MUST mechanical + 1 MUST judgment) corresponding to the doc's `## Rules` section
+- Adds 3 `rules/go/*.yml` ast-grep YAMLs for the mechanical rules; the judgment rule carries `Enforcement: judgment`
+- Runs `make build-index` so `rules/index.json` grows from 9 entries to 13
+- Mirrors the proven `bootstrap-rules-go-time-injection.md` + `bootstrap-rules-go-error-wrapping.md` shape
+- Scope note: doc lists 6 rules; this prompt extracts 4. Skipped: #3 ("fix on first attempt" — process rule, not enforceable) and #6 ("lock/PID files 0600" — covered by rule 1 which already mandates 0600 for ALL files)
+</summary>
+
+<objective>
+Following the schema in `docs/rule-block-schema.md` and the ast-grep conventions in `docs/ast-grep-rule-writing-guide.md`, extract four rules from `docs/go-security-linting.md` as inline `### RULE` blocks, write ast-grep YAML detectors for the three mechanical rules, and refresh `rules/index.json` via the walker. Every block must conform to the schema (Owner, Applies when, Enforcement fields, ID format `<lang>/<topic>/<slug>`, anchor = id verbatim).
+</objective>
+
+<context>
+Read `CLAUDE.md` for project conventions, including the doc-agent alignment table (`go-security-linting.md` → `go-security-specialist`).
+Read `docs/rule-block-schema.md` for the rule-block contract — required fields, level tokens, ID format, anchor rule (`anchor == id` verbatim).
+Read `docs/ast-grep-rule-writing-guide.md` for the YAML conventions — frontmatter shape, pattern strategies, pitfalls (especially the `main.go` + `**/main.go` dual-ignore + `**/mocks/**` defaults), smoke testing.
+Read `docs/go-security-linting.md` — the doc to migrate. The `## Rules` section (around line 41) lists the rules; the `## File Permissions`, `## File Path from Variable`, and `## Subprocess from Variable` sections provide Bad/Good code snippets.
+Read `docs/go-context-cancellation-in-loops.md` lines 160-192 — the canonical pilot `### RULE` block. The new blocks MUST match its formatting exactly: heading line `### RULE <id> (LEVEL)`, then bolded fields `**Owner**:`, `**Applies when**:`, `**Enforcement**:`, then `**Why**:`, then `#### Bad` / `#### Good` code blocks.
+Read `rules/go/no-fmt-errorf.yml`, `rules/go/no-time-now-direct.yml` — canonical small ast-grep YAMLs. Match their shape.
+Read `scripts/build-index.py` and run `python3 scripts/build-index.py` once to see the current `rules/index.json` shape (9 entries) before changes.
+</context>
+
+<requirements>
+1. Append four `### RULE` blocks at the END of `docs/go-security-linting.md` (after the existing `## Checklist` section). Do NOT modify any prose above. The four blocks, in order:
+
+**Rule 1 — MUST mechanical**
+- Heading: `### RULE go-security/file-perms-too-permissive (MUST)`
+- Owner: `go-security-specialist`
+- Applies when: `os.WriteFile($PATH, $DATA, $PERM)` or `os.OpenFile($PATH, $FLAGS, $PERM)` calls in a `*.go` file outside `*_test.go` and `vendor/`, where `$PERM` is a literal octal that is NOT `0600` / `0o600`.
+- Enforcement: `rules/go/file-perms-too-permissive.yml`
+- Why: world-readable file permissions (e.g. `0644`) expose configuration data, lock files, and other artifacts to any process on the host. gosec G306 flags this; the convention is owner-only `0600` for ALL files unless there is a specific reason documented via `#nosec` with explanation.
+- Bad/Good snippets: reuse the doc's `## File Permissions` section (`os.WriteFile(path, data, 0644)` → `os.WriteFile(path, data, 0600)`).
+
+**Rule 2 — MUST mechanical**
+- Heading: `### RULE go-security/dir-perms-too-permissive (MUST)`
+- Owner: `go-security-specialist`
+- Applies when: `os.MkdirAll($PATH, $PERM)` or `os.Mkdir($PATH, $PERM)` calls in a `*.go` file outside `*_test.go` and `vendor/`, where `$PERM` is a literal octal that is NOT `0750` / `0o750`.
+- Enforcement: `rules/go/dir-perms-too-permissive.yml`
+- Why: world-readable directories (e.g. `0755`) expose contents to any process on the host. The convention is `0750` (owner-rwx + group-rx, no world) for ALL agent-created directories.
+- Bad/Good snippets: reuse the doc's `## File Permissions` `MkdirAll` example.
+
+**Rule 3 — MUST mechanical**
+- Heading: `### RULE go-security/nosec-requires-reason (MUST)`
+- Owner: `go-security-specialist`
+- Applies when: a `// #nosec <CODE>` comment in a `*.go` file outside `*_test.go` and `vendor/` appears WITHOUT a `-- <reason>` text component on the same line.
+- Enforcement: `rules/go/nosec-requires-reason.yml`
+- Why: bare `#nosec` suppresses a finding without explaining why the input is trusted. The next reviewer has no audit trail. Mandate `// #nosec G304 -- path from internal ListQueued(), not user input` style.
+- Bad/Good snippets: reuse the doc's `## File Path from Variable` + `## Subprocess from Variable` good examples.
+
+**Rule 4 — MUST judgment**
+- Heading: `### RULE go-security/chmod-return-checked (MUST)`
+- Owner: `go-security-specialist`
+- Applies when: an `os.Chmod($PATH, $PERM)` call in a `*.go` file outside `*_test.go` and `vendor/` whose return value is discarded (no `if err := os.Chmod(...); err != nil` wrapper, no `_ = os.Chmod(...)` with an explanatory comment). Detecting "return value used in error check" requires reading the surrounding statement — pure ast-grep cannot reliably distinguish a checked `os.Chmod(...)` from an unchecked one without false positives.
+- Enforcement: `judgment` (no ast-grep — return-value-check semantics require whole-statement reasoning).
+- Why: silent `os.Chmod` failures leave file permissions in an unexpected state. The convention is either `if err := os.Chmod(...); err != nil { return ... }` or explicit `_ = os.Chmod(...)` with a comment explaining why the error is ignored.
+- Bad/Good snippets: inline the following minimal pair (the doc doesn't have explicit Bad/Good code for this rule):
+
+  Bad:
+  ```go
+  os.Chmod(path, 0600)
+  ```
+
+  Good:
+  ```go
+  if err := os.Chmod(path, 0600); err != nil {
+      return errors.Wrapf(ctx, err, "chmod %s", path)
+  }
+  ```
+
+Each block must follow the canonical pilot's exact formatting (`docs/go-context-cancellation-in-loops.md:160-192`).
+
+2. Create `rules/go/file-perms-too-permissive.yml`:
+   - `id: go-security/file-perms-too-permissive`
+   - `language: go`
+   - `severity: error`
+   - `message`: 3-line block — short summary, blank line, `See docs/go-security-linting.md (RULE go-security/file-perms-too-permissive).`
+   - `rule`: use `any:` alternation across known-bad permission patterns. Common bad values: `0644`, `0o644`, `0666`, `0o666`, `0777`, `0o777`. Pattern guidance:
+     ```yaml
+     rule:
+       any:
+         - pattern: os.WriteFile($PATH, $DATA, 0644)
+         - pattern: os.WriteFile($PATH, $DATA, 0o644)
+         - pattern: os.WriteFile($PATH, $DATA, 0666)
+         - pattern: os.WriteFile($PATH, $DATA, 0o666)
+         - pattern: os.WriteFile($PATH, $DATA, 0777)
+         - pattern: os.WriteFile($PATH, $DATA, 0o777)
+         - pattern: os.OpenFile($PATH, $FLAGS, 0644)
+         - pattern: os.OpenFile($PATH, $FLAGS, 0o644)
+         - pattern: os.OpenFile($PATH, $FLAGS, 0666)
+         - pattern: os.OpenFile($PATH, $FLAGS, 0o666)
+     ```
+     Alternative: detect any `os.WriteFile`/`os.OpenFile` call with constraints on the perm metavariable — only acceptable if the constraint correctly excludes `0600` / `0o600` and the pattern is verified against a synthetic file.
+   - `ignores`: `main.go`, `**/main.go`, `**/*_test.go`, `vendor/**`, `**/vendor/**`, `**/mocks/**`
+
+3. Create `rules/go/dir-perms-too-permissive.yml`:
+   - `id: go-security/dir-perms-too-permissive`
+   - `language: go`
+   - `severity: error`
+   - `message`: 3-line block referencing the doc
+   - `rule`: similar `any:` alternation across `0755`, `0o755`, `0777`, `0o777`, `0700` (too restrictive for some workflows but uncommon as a bad value — include if simple) for `os.MkdirAll` and `os.Mkdir`. Bad values to cover at minimum:
+     ```yaml
+     rule:
+       any:
+         - pattern: os.MkdirAll($PATH, 0755)
+         - pattern: os.MkdirAll($PATH, 0o755)
+         - pattern: os.MkdirAll($PATH, 0777)
+         - pattern: os.MkdirAll($PATH, 0o777)
+         - pattern: os.Mkdir($PATH, 0755)
+         - pattern: os.Mkdir($PATH, 0o755)
+         - pattern: os.Mkdir($PATH, 0777)
+         - pattern: os.Mkdir($PATH, 0o777)
+     ```
+   - `ignores`: same as rule 1
+
+4. Create `rules/go/nosec-requires-reason.yml`:
+   - `id: go-security/nosec-requires-reason`
+   - `language: go`
+   - `severity: error`
+   - `message`: 3-line block referencing the doc
+   - `rule`: detecting a comment's content is harder than detecting a Go AST node. ast-grep's `kind: comment` may suffice with a regex constraint. Pattern guidance:
+     ```yaml
+     rule:
+       kind: comment
+       regex: '#nosec'
+       not:
+         regex: '#nosec.*--'
+     ```
+     If `kind: comment` + `regex` + `not.regex` doesn't work in ast-grep's Go grammar, fall back to a simpler pattern that matches the `#nosec` literal text without the `--`:
+     ```yaml
+     rule:
+       pattern-regex: '//\s*#nosec\b(?!.*--)'
+     ```
+     Either acceptable as long as the smoke shows bare `#nosec G304` matches and `#nosec G304 -- reason` does not.
+   - `ignores`: same as rule 1
+
+5. Rule 4 (`chmod-return-checked`) has NO ast-grep YAML. Its `### RULE` block carries `Enforcement: judgment` (literal string, no path).
+
+6. No ast-grep smoke inside this prompt — operator runs `scripts/scan.sh <target-repo>` post-merge to confirm the detectors fire correctly on real code.
+
+7. Run `make build-index` to refresh `rules/index.json`. It must grow from 9 entries to **13 entries** (existing pilot + 3 go-time + 5 go-errors + 4 new go-security), with entries sorted by `id`.
+
+8. Verify each new index entry has:
+   - `owner: "go-security-specialist"`
+   - `doc_path: "docs/go-security-linting.md"`
+   - `anchor == id`
+   - `level in ("MUST","SHOULD","MAY")`
+   - non-empty `applies_when` and `enforcement`
+   - For rule 4: `enforcement: "judgment"` (literal string)
+
+9. Run `make precommit` — must pass.
+</requirements>
+
+<constraints>
+- Do NOT commit — dark-factory handles git
+- Do NOT modify the existing rule blocks in `docs/go-context-cancellation-in-loops.md`, `docs/go-time-injection.md`, or `docs/go-error-wrapping-guide.md`, or their YAMLs
+- Do NOT modify the schema doc or the ast-grep guide
+- Do NOT rewrite `docs/go-security-linting.md`'s existing prose — only APPEND the four `### RULE` blocks at the END of the file (after `## Checklist`)
+- Do NOT wire ast-grep into `make precommit`
+- Do NOT attempt `ast-grep scan` from inside the container
+- Use the same Bad/Good code snippets shown in `docs/go-security-linting.md` itself where they exist; for rule 4, synthesize minimal generic examples (User/Order/Product) per CLAUDE.md
+- Generic examples only — no Candle/Epic/Broker/SignalStore
+- No personal paths anywhere
+- No `Co-Authored-By:` or attribution trailers
+</constraints>
+
+<verification>
+Run from repo root:
+```bash
+# Four new ### RULE blocks added to the doc
+grep -c '^### RULE go-security/' docs/go-security-linting.md
+# Must return: 4
+
+# Three ast-grep YAMLs created
+test -f rules/go/file-perms-too-permissive.yml && \
+test -f rules/go/dir-perms-too-permissive.yml && \
+test -f rules/go/nosec-requires-reason.yml && \
+echo "yamls present: ok"
+
+# YAMLs reference the correct ids on their first line
+head -1 rules/go/file-perms-too-permissive.yml | grep -q '^id: go-security/file-perms-too-permissive' && echo "yaml1 id: ok"
+head -1 rules/go/dir-perms-too-permissive.yml | grep -q '^id: go-security/dir-perms-too-permissive' && echo "yaml2 id: ok"
+head -1 rules/go/nosec-requires-reason.yml | grep -q '^id: go-security/nosec-requires-reason' && echo "yaml3 id: ok"
+
+# All three YAMLs use severity: error
+for f in rules/go/file-perms-too-permissive.yml rules/go/dir-perms-too-permissive.yml rules/go/nosec-requires-reason.yml; do
+  head -5 "$f" | grep -q '^severity: error' || { echo "FAIL: $f missing severity: error"; exit 1; }
+done
+echo "severity: ok"
+
+# No YAML for the judgment rule (rule 4)
+test ! -f rules/go/chmod-return-checked.yml && echo "rule 4 has no YAML: ok"
+
+# rules/index.json now has 13 entries
+python3 -c "
+import json
+d = json.load(open('rules/index.json'))
+assert isinstance(d, list) and len(d) == 13, f'expected 13 entries, got {len(d)}'
+print(f'entries: {len(d)} ok')
+"
+
+# Expected ids present and sorted
+python3 -c "
+import json
+ids = [e['id'] for e in json.load(open('rules/index.json'))]
+expected = [
+    'go-context/cancel-check-in-loop',
+    'go-errors/inner-closure-no-double-wrap',
+    'go-errors/no-bare-return-err',
+    'go-errors/no-context-background-in-business-logic',
+    'go-errors/no-fmt-errorf',
+    'go-errors/sentinel-err-prefix-naming',
+    'go-security/chmod-return-checked',
+    'go-security/dir-perms-too-permissive',
+    'go-security/file-perms-too-permissive',
+    'go-security/nosec-requires-reason',
+    'go-time/inject-getter-not-create',
+    'go-time/no-time-now-direct',
+    'go-time/no-time-time-in-fields',
+]
+assert ids == expected, f'ids mismatch:\n  got: {ids}\n  expected: {expected}'
+print('ids sorted: ok')
+"
+
+# Four new entries owned by go-security-specialist + point at the right doc
+python3 -c "
+import json
+go_sec = [e for e in json.load(open('rules/index.json')) if e['id'].startswith('go-security/')]
+assert len(go_sec) == 4, f'expected 4 go-security/* entries, got {len(go_sec)}'
+for e in go_sec:
+    assert e['owner'] == 'go-security-specialist', f\"owner mismatch for {e['id']}: {e['owner']}\"
+    assert e['doc_path'] == 'docs/go-security-linting.md', f\"doc_path mismatch for {e['id']}\"
+    assert e['anchor'] == e['id'], f\"anchor != id for {e['id']}: {e['anchor']}\"
+    assert e['level'] in ('MUST','SHOULD','MAY'), f\"invalid level for {e['id']}: {e['level']}\"
+    assert e['applies_when'], f\"empty applies_when for {e['id']}\"
+    assert e['enforcement'], f\"empty enforcement for {e['id']}\"
+judgment_ids = {'go-security/chmod-return-checked'}
+for e in go_sec:
+    if e['id'] in judgment_ids:
+        assert e['enforcement'] == 'judgment', f\"{e['id']} enforcement must be literal 'judgment', got: {e['enforcement']}\"
+print('go-security entries: ok')
+"
+
+# Determinism — running build-index again produces identical bytes
+make build-index
+git diff --exit-code rules/index.json && echo "deterministic: ok"
+
+# make precommit clean
+make precommit
+```
+</verification>
diff --git a/rules/go/dir-perms-too-permissive.yml b/rules/go/dir-perms-too-permissive.yml
new file mode 100644
index 0000000..b90d09e
--- /dev/null
+++ b/rules/go/dir-perms-too-permissive.yml
@@ -0,0 +1,40 @@
+id: go-security/dir-perms-too-permissive
+language: go
+severity: error
+message: |
+  Directory permissions must not be world-readable.
+  Use 0750 (owner-rwx, group-rx, no world) for all directories created via os.MkdirAll or os.Mkdir.
+  See docs/go-security-linting.md (RULE go-security/dir-perms-too-permissive).
+rule:
+  any:
+    # Broadened enumeration — see file-perms-too-permissive.yml for rationale.
+    # 0700/0o700 intentionally NOT listed — owner-only directory (not
+    # world-readable), more restrictive than 0750, doesn't violate the rule's
+    # "no world-readable" intent.
+    - pattern: os.MkdirAll($PATH, 0740)
+    - pattern: os.MkdirAll($PATH, 0o740)
+    - pattern: os.MkdirAll($PATH, 0755)
+    - pattern: os.MkdirAll($PATH, 0o755)
+    - pattern: os.MkdirAll($PATH, 0770)
+    - pattern: os.MkdirAll($PATH, 0o770)
+    - pattern: os.MkdirAll($PATH, 0775)
+    - pattern: os.MkdirAll($PATH, 0o775)
+    - pattern: os.MkdirAll($PATH, 0777)
+    - pattern: os.MkdirAll($PATH, 0o777)
+    - pattern: os.Mkdir($PATH, 0740)
+    - pattern: os.Mkdir($PATH, 0o740)
+    - pattern: os.Mkdir($PATH, 0755)
+    - pattern: os.Mkdir($PATH, 0o755)
+    - pattern: os.Mkdir($PATH, 0770)
+    - pattern: os.Mkdir($PATH, 0o770)
+    - pattern: os.Mkdir($PATH, 0775)
+    - pattern: os.Mkdir($PATH, 0o775)
+    - pattern: os.Mkdir($PATH, 0777)
+    - pattern: os.Mkdir($PATH, 0o777)
+ignores:
+  - "main.go"
+  - "**/main.go"
+  - "**/*_test.go"
+  - "vendor/**"
+  - "**/vendor/**"
+  - "**/mocks/**"
diff --git a/rules/go/file-perms-too-permissive.yml b/rules/go/file-perms-too-permissive.yml
new file mode 100644
index 0000000..782ea7e
--- /dev/null
+++ b/rules/go/file-perms-too-permissive.yml
@@ -0,0 +1,54 @@
+id: go-security/file-perms-too-permissive
+language: go
+severity: error
+message: |
+  File permissions must not be world-readable.
+  Use 0600 (owner-only) for all files created via os.WriteFile or os.OpenFile.
+  See docs/go-security-linting.md (RULE go-security/file-perms-too-permissive).
+rule:
+  any:
+    # Broadened enumeration — ast-grep 0.43.0 metavariable constraints don't filter
+    # int literals, so we list common gosec-flagged permissive octals explicitly.
+    # NOT exhaustive; uncommon values (e.g. 0641) slip through and are caught by
+    # gosec G306 directly + the judgment-tier review.
+    - pattern: os.WriteFile($PATH, $DATA, 0644)
+    - pattern: os.WriteFile($PATH, $DATA, 0o644)
+    - pattern: os.WriteFile($PATH, $DATA, 0640)
+    - pattern: os.WriteFile($PATH, $DATA, 0o640)
+    - pattern: os.WriteFile($PATH, $DATA, 0660)
+    - pattern: os.WriteFile($PATH, $DATA, 0o660)
+    - pattern: os.WriteFile($PATH, $DATA, 0664)
+    - pattern: os.WriteFile($PATH, $DATA, 0o664)
+    - pattern: os.WriteFile($PATH, $DATA, 0666)
+    - pattern: os.WriteFile($PATH, $DATA, 0o666)
+    # 0700/0o700 intentionally NOT listed — owner-only (not world-readable),
+    # more restrictive than 0600, doesn't violate the rule's "no world-readable" intent.
+    - pattern: os.WriteFile($PATH, $DATA, 0744)
+    - pattern: os.WriteFile($PATH, $DATA, 0o744)
+    - pattern: os.WriteFile($PATH, $DATA, 0755)
+    - pattern: os.WriteFile($PATH, $DATA, 0o755)
+    - pattern: os.WriteFile($PATH, $DATA, 0777)
+    - pattern: os.WriteFile($PATH, $DATA, 0o777)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0644)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0o644)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0640)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0o640)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0660)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0o660)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0664)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0o664)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0666)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0o666)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0744)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0o744)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0755)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0o755)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0777)
+    - pattern: os.OpenFile($PATH, $FLAGS, 0o777)
+ignores:
+  - "main.go"
+  - "**/main.go"
+  - "**/*_test.go"
+  - "vendor/**"
+  - "**/vendor/**"
+  - "**/mocks/**"
diff --git a/rules/go/nosec-requires-reason.yml b/rules/go/nosec-requires-reason.yml
new file mode 100644
index 0000000..0e9436f
--- /dev/null
+++ b/rules/go/nosec-requires-reason.yml
@@ -0,0 +1,16 @@
+id: go-security/nosec-requires-reason
+language: go
+severity: error
+message: |
+  #nosec comments must include a `-- <reason>` explanation.
+  Bare suppressions give no audit trail for the next reviewer.
+  See docs/go-security-linting.md (RULE go-security/nosec-requires-reason).
+rule:
+  pattern-regex: '//\s*#nosec\b(?!.*--)'
+ignores:
+  - "main.go"
+  - "**/main.go"
+  - "**/*_test.go"
+  - "vendor/**"
+  - "**/vendor/**"
+  - "**/mocks/**"
diff --git a/rules/index.json b/rules/index.json
index c85143a..b152378 100644
--- a/rules/index.json
+++ b/rules/index.json
@@ -53,6 +53,42 @@
     "level": "SHOULD",
     "owner": "go-error-assistant"
   },
+  {
+    "anchor": "go-security/chmod-return-checked",
+    "applies_when": "an `os.Chmod($PATH, $PERM)` call in a `*.go` file outside `*_test.go` and `vendor/` whose return value is discarded (no `if err := os.Chmod(...); err != nil` wrapper, no `_ = os.Chmod(...)` with an explanatory comment). Detecting \"return value used in error check\" requires reading the surrounding statement — pure ast-grep cannot reliably distinguish a checked `os.Chmod(...)` from an unchecked one without false positives.",
+    "doc_path": "docs/go-security-linting.md",
+    "enforcement": "judgment",
+    "id": "go-security/chmod-return-checked",
+    "level": "MUST",
+    "owner": "go-security-specialist"
+  },
+  {
+    "anchor": "go-security/dir-perms-too-permissive",
+    "applies_when": "`os.MkdirAll($PATH, $PERM)` or `os.Mkdir($PATH, $PERM)` calls in a `*.go` file outside `*_test.go` and `vendor/`, where `$PERM` is a literal octal that is NOT `0750` / `0o750`.",
+    "doc_path": "docs/go-security-linting.md",
+    "enforcement": "`rules/go/dir-perms-too-permissive.yml`",
+    "id": "go-security/dir-perms-too-permissive",
+    "level": "MUST",
+    "owner": "go-security-specialist"
+  },
+  {
+    "anchor": "go-security/file-perms-too-permissive",
+    "applies_when": "`os.WriteFile($PATH, $DATA, $PERM)` or `os.OpenFile($PATH, $FLAGS, $PERM)` calls in a `*.go` file outside `*_test.go` and `vendor/`, where `$PERM` is a literal octal that is NOT `0600` / `0o600`.",
+    "doc_path": "docs/go-security-linting.md",
+    "enforcement": "`rules/go/file-perms-too-permissive.yml`",
+    "id": "go-security/file-perms-too-permissive",
+    "level": "MUST",
+    "owner": "go-security-specialist"
+  },
+  {
+    "anchor": "go-security/nosec-requires-reason",
+    "applies_when": "a `// #nosec <CODE>` comment in a `*.go` file outside `*_test.go` and `vendor/` appears WITHOUT a `-- <reason>` text component on the same line.",
+    "doc_path": "docs/go-security-linting.md",
+    "enforcement": "`rules/go/nosec-requires-reason.yml`",
+    "id": "go-security/nosec-requires-reason",
+    "level": "MUST",
+    "owner": "go-security-specialist"
+  },
   {
     "anchor": "go-time/inject-getter-not-create",
     "applies_when": "a factory or constructor file outside `main.go` calls `libtime.NewCurrentDateTime()`.",