diff --git a/.github/workflows/ci-host.yaml b/.github/workflows/ci-host.yaml
index 1346ea281fc..60bcecc3471 100644
--- a/.github/workflows/ci-host.yaml
+++ b/.github/workflows/ci-host.yaml
@@ -16,6 +16,7 @@ on:
       - ".github/workflows/ci-host.yaml"
       - "package.json"
       - "pnpm-lock.yaml"
+      - "pnpm-workspace.yaml"
       # CI boot path: see comment on the equivalent block in ci.yaml.
       - ".mise.toml"
       - ".github/actions/**"
@@ -149,7 +150,7 @@ jobs:
           use_cache=true
           while IFS= read -r file; do
             case "$file" in
-              packages/realm-server/*|packages/runtime-common/*|packages/postgres/*|packages/boxel-ui/*|package.json|pnpm-lock.yaml)
+              packages/realm-server/*|packages/runtime-common/*|packages/postgres/*|packages/boxel-ui/*|package.json|pnpm-lock.yaml|pnpm-workspace.yaml)
                 use_cache=false
                 echo "Index-behavior change detected: $file"
                 break
diff --git a/.github/workflows/ci-software-factory.yaml b/.github/workflows/ci-software-factory.yaml
index cf2a6bbab57..0d8b8a2f24c 100644
--- a/.github/workflows/ci-software-factory.yaml
+++ b/.github/workflows/ci-software-factory.yaml
@@ -20,6 +20,7 @@ on:
       - "packages/software-factory/**"
       - "package.json"
       - "pnpm-lock.yaml"
+      - "pnpm-workspace.yaml"
       # CI boot path: see comment on the equivalent block in ci.yaml.
       - ".mise.toml"
       - ".github/actions/**"
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index ae6ff4b60d0..9cc60358a02 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -54,6 +54,7 @@ jobs:
               - 'packages/runtime-common/**'
               - 'package.json'
               - 'pnpm-lock.yaml'
+              - 'pnpm-workspace.yaml'
               # CI boot path. Each gated suite runs `./.github/actions/init`
               # (which calls `jdx/mise-action`, sourcing `.mise.toml` for tool
               # versions) and then `mise run test-services:*` (which sources
diff --git a/.github/workflows/pr-boxel-ui.yml b/.github/workflows/pr-boxel-ui.yml
index 35878b92eb1..464af24625b 100644
--- a/.github/workflows/pr-boxel-ui.yml
+++ b/.github/workflows/pr-boxel-ui.yml
@@ -8,6 +8,7 @@ on:
       - ".github/workflows/pr-boxel-ui.yml"
       - "package.json"
       - "pnpm-lock.yaml"
+      - "pnpm-workspace.yaml"
 
 permissions:
   contents: read
diff --git a/.github/workflows/preview-host.yml b/.github/workflows/preview-host.yml
index 591826f3dad..2ec9cc40d2d 100644
--- a/.github/workflows/preview-host.yml
+++ b/.github/workflows/preview-host.yml
@@ -10,6 +10,7 @@ on:
       - ".github/workflows/preview-host.yml"
       - "package.json"
       - "pnpm-lock.yaml"
+      - "pnpm-workspace.yaml"
 
 concurrency:
   group: preview-host-${{ github.head_ref || github.run_id }}
diff --git a/pnpm-workspace.yaml b/pnpm-workspace.yaml
index 96e487c5f35..f7953459284 100644
--- a/pnpm-workspace.yaml
+++ b/pnpm-workspace.yaml
@@ -257,6 +257,15 @@ catalog:
   yaml: ^2.5.1
   yargs: ^17.5.1
 
+# pnpm 11 defaults this to `install`, making every `pnpm run` first check
+# node_modules freshness and silently run a full install when the check
+# fails. The check never passes in CI, so each of the ~9 services `run-p`
+# boots kicks off its own concurrent workspace-wide install into the same
+# node_modules; when they collide badly enough, start:matrix never reaches
+# `docker run` and the shard dies with "Failed to reach Synapse". Disabling
+# restores pnpm 10 behavior: scripts run against node_modules as-is.
+verifyDepsBeforeRun: false
+
 minimumReleaseAge: 1440
 minimumReleaseAgeExclude:
   - "@glint/ember-tsc"