docs: add Terragrunt migration skill and fix stale PRD statuses

.github/workflows/test.yml

@@ -622,7 +622,21 @@ jobs:
         with:
           egress-policy: audit
 
+      # A whole-run cancellation (e.g. superseded by a newer push to the same
+      # PR) skips the `test` matrix before it ever dispatches shard jobs, so
+      # the API query below would legitimately find 0 shards - not a real
+      # anomaly to fail loudly on. cancelled() reflects the run itself, unlike
+      # needs.test.result, which reports "skipped" for both this case and a
+      # genuine upstream (e.g. build) failure - so it can't replace this
+      # check. cancelled() is only valid in an `if:`, not inside a script, so
+      # the verification steps below are skipped via `if: ${{ !cancelled() }}`
+      # rather than early-exiting from within their run: blocks.
+      - name: Skip verification (workflow run was cancelled)
+        if: ${{ cancelled() }}
+        run: echo "workflow run was cancelled (e.g. superseded by a newer push); nothing to verify"
+
       - name: Check per-OS test matrix result
+        if: ${{ !cancelled() }}
         env:
           GH_TOKEN: ${{ github.token }}
           CHECK: ${{ matrix.check }}
@@ -670,7 +684,7 @@ jobs:
         # terraform-registry-cache only runs a linux/windows matrix (no macos
         # leg - see its `matrix.flavor` above), so its aggregated result must
         # not gate the macos alias.
-        if: matrix.check != 'Acceptance Tests (macos)'
+        if: ${{ !cancelled() && matrix.check != 'Acceptance Tests (macos)' }}
         run: |
           if [ "${{ needs.terraform-registry-cache.result }}" != "success" ]; then
             echo "terraform-registry-cache result was '${{ needs.terraform-registry-cache.result }}'"
@@ -1099,7 +1113,15 @@ jobs:
         with:
           egress-policy: audit
 
+      # See the matching comment on test-required's per-OS check step: a
+      # whole-run cancellation is not a genuine k3s failure, and cancelled()
+      # is only valid in an `if:`, not inside a script.
+      - name: Skip verification (workflow run was cancelled)
+        if: ${{ cancelled() }}
+        run: echo "workflow run was cancelled (e.g. superseded by a newer push); nothing to verify"
+
       - name: Check k3s matrix result
+        if: ${{ !cancelled() }}
         run: |
           if [ "${{ needs.k3s.result }}" != "success" ]; then
             echo "k3s matrix result was '${{ needs.k3s.result }}'"

agent-skills/skills/atmos-migration/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: atmos-migration
-description: "Migrating to Atmos from existing IaC: techniques, tactics, and design patterns for native Terraform, Terraform Workspaces, and Terramate — minimum-disruption paths, file-layout options, workspace mapping, tag/generate_hcl/script decomposition, and the remote-state bridge for progressive migration"
+description: "Migrating to Atmos from existing IaC: techniques, tactics, and design patterns for native Terraform, Terraform Workspaces, Terramate, and Terragrunt — minimum-disruption paths, file-layout options, workspace mapping, tag/generate_hcl/script decomposition, and the remote-state bridge for progressive migration"
 metadata:
   copyright: Copyright Cloud Posse, LLC 2026
   version: "1.0.0"
@@ -11,6 +11,7 @@ references:
   - references/remote-state-bridge.md
   - references/from-terramate.md
   - references/from-component-updater.md
+  - references/from-terragrunt.md
 ---
 
 # Migrating to Atmos
@@ -26,7 +27,8 @@ For full prose tutorials aimed at end users, link to:
 
 - [Migrating from Native Terraform](https://atmos.tools/migration/native-terraform)
 - [Migrating from Terraform Workspaces](https://atmos.tools/migration/terraform-workspaces)
-- [Migrating from Terragrunt](https://atmos.tools/migration/terragrunt) (not covered by this skill)
+- [Migrating from Terragrunt](https://atmos.tools/migration/terragrunt) -- see
+  [from-terragrunt.md](references/from-terragrunt.md) for the agent-actionable recipes
 - Migrating from Terramate -- covered by this skill via
   [references/from-terramate.md](references/from-terramate.md) (no atmos.tools tutorial yet)
 
@@ -80,6 +82,7 @@ different reference:
 | `.tm.hcl` files, `stack.tm.hcl`, `generate_hcl` blocks (Terramate project) | [from-terramate.md](references/from-terramate.md) |
 | Need to read outputs from un-migrated TF (legacy or another repo)    | [remote-state-bridge.md](references/remote-state-bridge.md) |
 | `cloudposse/github-action-atmos-component-updater`                   | [from-component-updater.md](references/from-component-updater.md) |
+| Terragrunt (`terragrunt.hcl` or `terragrunt.stack.hcl`)               | [from-terragrunt.md](references/from-terragrunt.md) |
 
 The remote-state-bridge pattern is what makes **progressive, component-by-component migration**
 possible. Without it, a team is forced into a big-bang cutover. Cover it any time the user has
@@ -196,3 +199,5 @@ Things to push back on if a user (or another agent) proposes them during migrati
 - [References/from-terramate.md](references/from-terramate.md) -- construct-by-construct mapping
   from Terramate (`stack.tm.hcl`, globals, `generate_hcl`, `script{}`, tags/labels) to Atmos,
   including the one remaining known gap (`.tmtriggers`)
+- [References/from-terragrunt.md](references/from-terragrunt.md) -- concept mapping and migration
+  workflow for classic Terragrunt and Terragrunt Stacks