diff --git a/.github/workflows/security.yml b/.github/workflows/security.yml
index 0b69c6d7..ff8bc862 100644
--- a/.github/workflows/security.yml
+++ b/.github/workflows/security.yml
@@ -141,6 +141,17 @@ jobs:
         shell: pwsh
         run: ./scripts/sbom-validate-check.ps1 -SelfCheck
 
+  # Blocking C06 L33 Socket.dev posture evidence — hermetic SelfCheck only.
+  # Does not call Socket API or claim live org GitHub App install.
+  socket-posture:
+    name: Socket posture SelfCheck
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
+      - name: Socket.dev posture + in-repo dependency scan anchors
+        shell: pwsh
+        run: ./scripts/socket-posture-check.ps1 -SelfCheck
+
   # Blocking C06 L53 protected-environment checklist — hermetic SelfCheck only.
   # Does not claim live GitHub Environment wiring or full SLSA Build L3 attestation.
   slsa-protected-env:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c0923c68..5a958201 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,8 @@ Follows [Keep a Changelog](https://keepachangelog.com/); versioning is [SemVer](
 
 ### Added
 
+- Socket.dev supply-chain posture (C06 L33): `docs/ops/socket-posture.md`, `socket-posture.json`, `scripts/socket-posture-check.ps1 -SelfCheck`, blocking `security.yml` job, `tests/socket_posture.rs`.
+
 - Wave-43 scope (396/402): consolidated `WAVE43_SCOPE.md` + `docs/ops/WAVE43_PERT.md` — five parallel carry-forward lanes (`w43-daemon-graph-hard`, `w43-jemalloc-default-on`, `w43-load-macro-gate`, `w43-sl-viewer-help`, `w43-socket-posture`) from Wave-42 deferred gaps.
 
 - Blocking alloc-profile / dhat PR gate (C00 L8): `.github/workflows/alloc-profile-hard.yml`, expanded `alloc-profile-check.ps1 -SelfCheck` anchors, `tests/alloc_profile_hard.rs` (soft `ops-load` job retained).
diff --git a/SECURITY.md b/SECURITY.md
index c490f4c3..fd76a048 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -71,6 +71,7 @@ Critical supply-chain or remote-code issues may be accelerated at maintainer dis
 - Advisory scanning: `cargo audit` job in .github/workflows/security.yml.
 - SBOM upload: qgate uploads `sbom-cyclonedx` artifact from `target/sbom.cdx.json`.
 - CVE feed subscription (GHSA + OSV + NVD): maintainer process and evidence links in [`docs/ops/cve-feed-subscription.md`](docs/ops/cve-feed-subscription.md). Hermetic proof: `pwsh ./scripts/cve-feed-check.ps1 -SelfCheck`.
+- Socket.dev supply-chain posture (optional org GitHub App complement): policy SSOT in [`docs/ops/socket-posture.md`](docs/ops/socket-posture.md). Hermetic proof: `pwsh ./scripts/socket-posture-check.ps1 -SelfCheck`. Live org install is **not** attestable from this repository.
 
 ## Cryptography inventory
 
diff --git a/docs/ops/cve-feed-subscription.md b/docs/ops/cve-feed-subscription.md
index f4576e64..20462ceb 100644
--- a/docs/ops/cve-feed-subscription.md
+++ b/docs/ops/cve-feed-subscription.md
@@ -9,6 +9,7 @@ This document does **not** claim maintainer 2FA enforcement (L36) — org-level
 2FA is not verifiable from checkout (see [`branch-protection.md`](branch-protection.md)).
 
 Related: [`SECURITY.md`](../../SECURITY.md) (reporting + supply-chain policy),
+[`socket-posture.md`](socket-posture.md) (optional Socket.dev complement),
 [`deny.toml`](../../deny.toml) (cargo-deny advisories),
 [`.github/workflows/security.yml`](../../.github/workflows/security.yml)
 (cargo-deny + cargo-audit), [`.github/dependabot.yml`](../../.github/dependabot.yml),
diff --git a/docs/ops/socket-posture.json b/docs/ops/socket-posture.json
new file mode 100644
index 00000000..39c93c05
--- /dev/null
+++ b/docs/ops/socket-posture.json
@@ -0,0 +1,21 @@
+{
+  "schema_version": 1,
+  "purpose": "Socket.dev supply-chain telemetry posture (C06 L33 complement to cargo-deny/audit)",
+  "github_app": "Socket Security for GitHub",
+  "expected_pr_checks": [
+    "Socket Security: Pull Request Alerts",
+    "Socket Security: Project Report"
+  ],
+  "in_repo_blocking": [
+    "cargo deny check",
+    "cargo audit",
+    "gitleaks",
+    "trufflehog"
+  ],
+  "verify_command": "./scripts/socket-posture-check.ps1 -SelfCheck",
+  "not_verifiable_in_repo": [
+    "Socket.dev org API token",
+    "GitHub App install state",
+    "Live dashboard policy thresholds"
+  ]
+}
diff --git a/docs/ops/socket-posture.md b/docs/ops/socket-posture.md
new file mode 100644
index 00000000..a150b220
--- /dev/null
+++ b/docs/ops/socket-posture.md
@@ -0,0 +1,72 @@
+# Socket.dev supply-chain posture
+
+Status: **C06 L33** complement — documents how SessionLedger aligns with
+[Socket.dev](https://socket.dev) dependency-risk telemetry **alongside** in-repo
+blocking scans (`cargo deny`, `cargo audit`, gitleaks, TruffleHog). Machine
+proof: `pwsh ./scripts/socket-posture-check.ps1 -SelfCheck`.
+
+Policy manifest: [`socket-posture.json`](socket-posture.json).
+
+Related: [`SECURITY.md`](../../SECURITY.md),
+[`cve-feed-subscription.md`](cve-feed-subscription.md),
+[`.github/workflows/security.yml`](../../.github/workflows/security.yml),
+[`deny.toml`](../../deny.toml).
+
+## Layered controls
+
+| Layer | Role | Evidence in this repo |
+|-------|------|------------------------|
+| **In-repo blocking** | Primary PR gate for Rust advisories + secrets | `cargo-deny`, `cargo-audit`, gitleaks, TruffleHog in `security.yml` |
+| **GHSA/OSV/NVD feeds** | Maintainer triage beyond a single bot | [`cve-feed-subscription.md`](cve-feed-subscription.md) |
+| **Socket.dev (optional org)** | Supply-chain behavior scoring on PRs when the GitHub App is installed | Expected check names in `socket-posture.json`; **not** enforced by this SelfCheck |
+
+SessionLedger does **not** embed a Socket API token or run Socket CLI in CI.
+When the org installs the Socket GitHub App, PRs may show **Socket Security: Pull Request Alerts** and **Project Report** checks (third-party; informational unless branch protection requires them).
+
+## Maintainer process
+
+### 1. Keep in-repo scans green (required)
+
+Every PR / push to `main` runs [`.github/workflows/security.yml`](../../.github/workflows/security.yml):
+
+- `cargo deny check` — advisory policy from [`deny.toml`](../../deny.toml)
+- `cargo audit` — RustSec / GHSA-backed advisories
+- gitleaks + TruffleHog — secret scanning
+
+Triage failures before merging; do not rely on Socket alone to waive deny/audit hits.
+
+### 2. Optional Socket.dev GitHub App (org)
+
+1. Org admin installs **Socket Security for GitHub** on `KooshaPari/SessionLedger`.
+2. Confirm PR checks include the names listed in [`socket-posture.json`](socket-posture.json).
+3. Review Socket alerts as **supplementary** signal (typosquatting, install scripts,
+   risky postinstall) — cross-check against `cargo deny` / `cargo audit` before merge.
+4. Record org install date in a maintainer note if branch protection later requires Socket checks.
+
+### 3. When Socket is absent
+
+In-repo `cargo-deny`, `cargo-audit`, Renovate/Dependabot, and
+[`cve-feed-subscription.md`](cve-feed-subscription.md) remain the authoritative
+dependency-risk surface. Absence of Socket checks is **not** a merge blocker
+unless org policy adds them to required checks.
+
+## SelfCheck gate
+
+| Check | Status |
+|-------|--------|
+| `socket-posture-check.ps1 -SelfCheck` | **done** — docs + `security.yml` anchor |
+| Live Socket API / org install | **NOT_VERIFIABLE_IN_REPO** |
+
+Hermetic SelfCheck validates policy doc anchors, `SECURITY.md` cross-link,
+`security.yml` job wiring, and complementary scan evidence paths. No network,
+no Socket API token, no false claim of live org install.
+
+## Done / unpaid
+
+| Item | Status |
+|------|--------|
+| Policy SSOT + JSON manifest | **done** |
+| Blocking `security.yml` SelfCheck job | **done** |
+| `tests/socket_posture.rs` cargo wrapper | **done** |
+| Live Socket org API automation | **unpaid** — creds / org |
+| Branch-protection required Socket checks | **unpaid** — human Settings |
diff --git a/scripts/socket-posture-check.ps1 b/scripts/socket-posture-check.ps1
new file mode 100644
index 00000000..4e6c6ca3
--- /dev/null
+++ b/scripts/socket-posture-check.ps1
@@ -0,0 +1,166 @@
+<#
+.SYNOPSIS
+  Machine-check Socket.dev supply-chain posture doc anchors (C06 L33).
+
+.DESCRIPTION
+  Verifies docs/ops/socket-posture.md + socket-posture.json document Socket.dev
+  as an optional org GitHub App complement to in-repo cargo-deny / cargo-audit /
+  gitleaks / TruffleHog. Cross-checks SECURITY.md, security.yml job wiring, and
+  CVE feed subscription links.
+  Hermetic: no network, no Socket API token, no org install attestation.
+
+.PARAMETER SelfCheck
+  Explicit docs/path smoke (CI unit proof). Same checks as the default path.
+
+.EXAMPLE
+  pwsh ./scripts/socket-posture-check.ps1 -SelfCheck
+#>
+[CmdletBinding()]
+param(
+    [switch]$SelfCheck
+)
+
+Set-StrictMode -Version Latest
+$ErrorActionPreference = "Stop"
+
+$repoRoot = Split-Path -Parent $PSScriptRoot
+$docPath = Join-Path $repoRoot "docs/ops/socket-posture.md"
+$policyPath = Join-Path $repoRoot "docs/ops/socket-posture.json"
+$cveFeedPath = Join-Path $repoRoot "docs/ops/cve-feed-subscription.md"
+$securityPath = Join-Path $repoRoot "SECURITY.md"
+$denyPath = Join-Path $repoRoot "deny.toml"
+$securityWorkflow = Join-Path $repoRoot ".github/workflows/security.yml"
+$selfPath = Join-Path $repoRoot "scripts/socket-posture-check.ps1"
+$wrapperTest = Join-Path $repoRoot "tests/socket_posture.rs"
+
+function Assert-File {
+    param(
+        [Parameter(Mandatory = $true)][string]$Path,
+        [Parameter(Mandatory = $true)][string]$Label
+    )
+    if (-not (Test-Path -LiteralPath $Path -PathType Leaf)) {
+        throw "Missing $Label at '$Path'."
+    }
+}
+
+function Write-Check {
+    param([string]$Label, [bool]$Ok)
+    $mark = if ($Ok) { "PASS" } else { "FAIL" }
+    Write-Host "  [$mark] $Label"
+    return $Ok
+}
+
+function Test-DocContains {
+    param(
+        [Parameter(Mandatory = $true)][string]$Doc,
+        [Parameter(Mandatory = $true)][string]$Needle,
+        [Parameter(Mandatory = $true)][string]$Label,
+        [string]$Context = "docs/ops/socket-posture.md"
+    )
+    $ok = $Doc.Contains($Needle)
+    [void](Write-Check -Label $Label -Ok $ok)
+    if (-not $ok) {
+        throw "$Context missing required anchor: '$Needle'"
+    }
+}
+
+Write-Host "Socket.dev posture check (C06 L33)"
+if ($SelfCheck) {
+    Write-Host "Mode: SelfCheck (docs + evidence paths; no Socket API / no network)"
+}
+
+Assert-File -Path $docPath -Label "socket posture doc"
+Assert-File -Path $policyPath -Label "socket posture policy JSON"
+Assert-File -Path $cveFeedPath -Label "CVE feed subscription doc"
+Assert-File -Path $securityPath -Label "SECURITY.md"
+Assert-File -Path $denyPath -Label "deny.toml"
+Assert-File -Path $securityWorkflow -Label "security workflow"
+Assert-File -Path $selfPath -Label "socket posture check script"
+Assert-File -Path $wrapperTest -Label "socket_posture.rs test wrapper"
+
+$doc = Get-Content -LiteralPath $docPath -Raw
+$policy = Get-Content -LiteralPath $policyPath -Raw
+$cveFeed = Get-Content -LiteralPath $cveFeedPath -Raw
+$security = Get-Content -LiteralPath $securityPath -Raw
+$securityWf = Get-Content -LiteralPath $securityWorkflow -Raw
+
+Write-Host "Socket posture doc anchors:"
+Test-DocContains -Doc $doc -Needle "Socket.dev supply-chain posture" `
+    -Label "doc heading"
+Test-DocContains -Doc $doc -Needle "**C06 L33**" `
+    -Label "C06 L33 status"
+Test-DocContains -Doc $doc -Needle "## Layered controls" `
+    -Label "layered controls heading"
+Test-DocContains -Doc $doc -Needle "Socket Security: Pull Request Alerts" `
+    -Label "expected PR check name"
+Test-DocContains -Doc $doc -Needle "NOT_VERIFIABLE_IN_REPO" `
+    -Label "org install disclaimer"
+Test-DocContains -Doc $doc -Needle "socket-posture-check.ps1" `
+    -Label "SelfCheck script reference"
+Test-DocContains -Doc $doc -Needle "socket-posture-check.ps1 -SelfCheck" `
+    -Label "SelfCheck gate marked done"
+Test-DocContains -Doc $doc -Needle "cargo deny" `
+    -Label "cargo-deny named"
+Test-DocContains -Doc $doc -Needle "cargo audit" `
+    -Label "cargo-audit named"
+Test-DocContains -Doc $doc -Needle "cve-feed-subscription.md" `
+    -Label "CVE feed cross-link"
+
+Write-Host "Policy JSON anchors:"
+Test-DocContains -Doc $policy -Needle '"schema_version"' `
+    -Label "schema_version" -Context "socket-posture.json"
+Test-DocContains -Doc $policy -Needle "Socket Security: Pull Request Alerts" `
+    -Label "expected PR checks" -Context "socket-posture.json"
+Test-DocContains -Doc $policy -Needle "socket-posture-check.ps1" `
+    -Label "verify_command" -Context "socket-posture.json"
+
+Write-Host "Evidence path anchors:"
+Test-DocContains -Doc $security -Needle "docs/ops/socket-posture.md" `
+    -Label "SECURITY.md -> socket-posture" -Context "SECURITY.md"
+Test-DocContains -Doc $security -Needle "socket-posture-check.ps1" `
+    -Label "SECURITY.md SelfCheck reference" -Context "SECURITY.md"
+
+if ($securityWf -notmatch 'socket-posture-check\.ps1') {
+    throw "security.yml missing socket-posture-check.ps1 SelfCheck job."
+}
+[void](Write-Check -Label "security.yml socket-posture SelfCheck" -Ok $true)
+
+if ($securityWf -notmatch 'cargo-deny') {
+    throw "security.yml missing cargo-deny job/reference."
+}
+[void](Write-Check -Label "security.yml cargo-deny" -Ok $true)
+
+if ($securityWf -notmatch 'cargo.?audit') {
+    throw "security.yml missing cargo-audit job/reference."
+}
+[void](Write-Check -Label "security.yml cargo-audit" -Ok $true)
+
+if ($securityWf -notmatch 'gitleaks') {
+    throw "security.yml missing gitleaks job/reference."
+}
+[void](Write-Check -Label "security.yml gitleaks" -Ok $true)
+
+if ($securityWf -notmatch 'trufflehog') {
+    throw "security.yml missing trufflehog job/reference."
+}
+[void](Write-Check -Label "security.yml trufflehog" -Ok $true)
+
+if ($cveFeed -notmatch 'socket-posture') {
+    throw "cve-feed-subscription.md should cross-link socket-posture (complementary feeds)."
+}
+[void](Write-Check -Label "cve-feed socket cross-link" -Ok $true)
+
+$summary = @"
+## Socket posture SelfCheck
+
+SelfCheck passed: ``docs/ops/socket-posture.md`` anchors, ``socket-posture.json``
+manifest, SECURITY.md cross-link, and complementary cargo-deny / cargo-audit /
+gitleaks / TruffleHog evidence. Does not claim live Socket.org install.
+"@
+
+if ($env:GITHUB_STEP_SUMMARY) {
+    $summary | Out-File -FilePath $env:GITHUB_STEP_SUMMARY -Append -Encoding utf8
+}
+
+Write-Host "Socket posture SelfCheck passed (C06 L33; no Socket API / no org install claim)."
+exit 0
diff --git a/tests/socket_posture.rs b/tests/socket_posture.rs
new file mode 100644
index 00000000..c5fe5b66
--- /dev/null
+++ b/tests/socket_posture.rs
@@ -0,0 +1,32 @@
+//! Hermetic `SelfCheck` for Socket.dev supply-chain posture (C06 L33).
+//!
+//! Local: `pwsh ./scripts/socket-posture-check.ps1 -SelfCheck`
+
+use std::path::PathBuf;
+use std::process::Command;
+
+fn repo_root() -> PathBuf {
+    PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+}
+
+#[test]
+fn socket_posture_self_check_validates_policy_and_anchors() {
+    let script = repo_root().join("scripts/socket-posture-check.ps1");
+    assert!(script.is_file(), "expected socket posture script at {}", script.display());
+
+    let output = Command::new("pwsh")
+        .args(["-NoProfile", "-File", script.to_str().expect("utf-8 script path"), "-SelfCheck"])
+        .output()
+        .unwrap_or_else(|error| panic!("failed to spawn pwsh for SelfCheck: {error}"));
+
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        output.status.success(),
+        "socket-posture-check.ps1 -SelfCheck failed\nstdout:\n{stdout}\nstderr:\n{stderr}"
+    );
+    assert!(
+        stdout.contains("Socket posture SelfCheck passed"),
+        "expected SelfCheck success line, got:\n{stdout}"
+    );
+}