diff --git a/benchmark/SKILL.md b/benchmark/SKILL.md
index 46c23efc9..10f928e83 100644
--- a/benchmark/SKILL.md
+++ b/benchmark/SKILL.md
@@ -180,7 +180,13 @@ If `NEEDS_SETUP`:
      BUN_INSTALL_SHA="bab8acfb046aac8c72407bdcce903957665d655d7acaa3e11c7c4616beae68dd"
      tmpfile=$(mktemp)
      curl -fsSL "https://bun.sh/install" -o "$tmpfile"
-     actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     # shasum is macOS/perl; coreutils-only Linux ships sha256sum instead —
+     # resolve whichever exists so the verify never fails on a missing tool.
+     if command -v sha256sum >/dev/null 2>&1; then
+       actual_sha=$(sha256sum "$tmpfile" | awk '{print $1}')
+     else
+       actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     fi
      if [ "$actual_sha" != "$BUN_INSTALL_SHA" ]; then
        echo "ERROR: bun install script checksum mismatch" >&2
        echo "  expected: $BUN_INSTALL_SHA" >&2
diff --git a/canary/SKILL.md b/canary/SKILL.md
index 471a844be..3fb4009e4 100644
--- a/canary/SKILL.md
+++ b/canary/SKILL.md
@@ -412,7 +412,13 @@ If `NEEDS_SETUP`:
      BUN_INSTALL_SHA="bab8acfb046aac8c72407bdcce903957665d655d7acaa3e11c7c4616beae68dd"
      tmpfile=$(mktemp)
      curl -fsSL "https://bun.sh/install" -o "$tmpfile"
-     actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     # shasum is macOS/perl; coreutils-only Linux ships sha256sum instead —
+     # resolve whichever exists so the verify never fails on a missing tool.
+     if command -v sha256sum >/dev/null 2>&1; then
+       actual_sha=$(sha256sum "$tmpfile" | awk '{print $1}')
+     else
+       actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     fi
      if [ "$actual_sha" != "$BUN_INSTALL_SHA" ]; then
        echo "ERROR: bun install script checksum mismatch" >&2
        echo "  expected: $BUN_INSTALL_SHA" >&2
diff --git a/design-consultation/SKILL.md b/design-consultation/SKILL.md
index 5aff1b9e1..7a37599e1 100644
--- a/design-consultation/SKILL.md
+++ b/design-consultation/SKILL.md
@@ -498,7 +498,13 @@ If `NEEDS_SETUP`:
      BUN_INSTALL_SHA="bab8acfb046aac8c72407bdcce903957665d655d7acaa3e11c7c4616beae68dd"
      tmpfile=$(mktemp)
      curl -fsSL "https://bun.sh/install" -o "$tmpfile"
-     actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     # shasum is macOS/perl; coreutils-only Linux ships sha256sum instead —
+     # resolve whichever exists so the verify never fails on a missing tool.
+     if command -v sha256sum >/dev/null 2>&1; then
+       actual_sha=$(sha256sum "$tmpfile" | awk '{print $1}')
+     else
+       actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     fi
      if [ "$actual_sha" != "$BUN_INSTALL_SHA" ]; then
        echo "ERROR: bun install script checksum mismatch" >&2
        echo "  expected: $BUN_INSTALL_SHA" >&2
diff --git a/design-html/SKILL.md b/design-html/SKILL.md
index 1ebd2e5f1..044c204e0 100644
--- a/design-html/SKILL.md
+++ b/design-html/SKILL.md
@@ -486,7 +486,13 @@ If `NEEDS_SETUP`:
      BUN_INSTALL_SHA="bab8acfb046aac8c72407bdcce903957665d655d7acaa3e11c7c4616beae68dd"
      tmpfile=$(mktemp)
      curl -fsSL "https://bun.sh/install" -o "$tmpfile"
-     actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     # shasum is macOS/perl; coreutils-only Linux ships sha256sum instead —
+     # resolve whichever exists so the verify never fails on a missing tool.
+     if command -v sha256sum >/dev/null 2>&1; then
+       actual_sha=$(sha256sum "$tmpfile" | awk '{print $1}')
+     else
+       actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     fi
      if [ "$actual_sha" != "$BUN_INSTALL_SHA" ]; then
        echo "ERROR: bun install script checksum mismatch" >&2
        echo "  expected: $BUN_INSTALL_SHA" >&2
diff --git a/design-review/SKILL.md b/design-review/SKILL.md
index c8ce6d3cf..622d98b25 100644
--- a/design-review/SKILL.md
+++ b/design-review/SKILL.md
@@ -485,7 +485,13 @@ If `NEEDS_SETUP`:
      BUN_INSTALL_SHA="bab8acfb046aac8c72407bdcce903957665d655d7acaa3e11c7c4616beae68dd"
      tmpfile=$(mktemp)
      curl -fsSL "https://bun.sh/install" -o "$tmpfile"
-     actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     # shasum is macOS/perl; coreutils-only Linux ships sha256sum instead —
+     # resolve whichever exists so the verify never fails on a missing tool.
+     if command -v sha256sum >/dev/null 2>&1; then
+       actual_sha=$(sha256sum "$tmpfile" | awk '{print $1}')
+     else
+       actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     fi
      if [ "$actual_sha" != "$BUN_INSTALL_SHA" ]; then
        echo "ERROR: bun install script checksum mismatch" >&2
        echo "  expected: $BUN_INSTALL_SHA" >&2
diff --git a/devex-review/SKILL.md b/devex-review/SKILL.md
index 4b38c42b4..65fd6d53b 100644
--- a/devex-review/SKILL.md
+++ b/devex-review/SKILL.md
@@ -475,7 +475,13 @@ If `NEEDS_SETUP`:
      BUN_INSTALL_SHA="bab8acfb046aac8c72407bdcce903957665d655d7acaa3e11c7c4616beae68dd"
      tmpfile=$(mktemp)
      curl -fsSL "https://bun.sh/install" -o "$tmpfile"
-     actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     # shasum is macOS/perl; coreutils-only Linux ships sha256sum instead —
+     # resolve whichever exists so the verify never fails on a missing tool.
+     if command -v sha256sum >/dev/null 2>&1; then
+       actual_sha=$(sha256sum "$tmpfile" | awk '{print $1}')
+     else
+       actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     fi
      if [ "$actual_sha" != "$BUN_INSTALL_SHA" ]; then
        echo "ERROR: bun install script checksum mismatch" >&2
        echo "  expected: $BUN_INSTALL_SHA" >&2
diff --git a/open-gstack-browser/SKILL.md b/open-gstack-browser/SKILL.md
index a18696cc7..44b569087 100644
--- a/open-gstack-browser/SKILL.md
+++ b/open-gstack-browser/SKILL.md
@@ -183,7 +183,13 @@ If `NEEDS_SETUP`:
      BUN_INSTALL_SHA="bab8acfb046aac8c72407bdcce903957665d655d7acaa3e11c7c4616beae68dd"
      tmpfile=$(mktemp)
      curl -fsSL "https://bun.sh/install" -o "$tmpfile"
-     actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     # shasum is macOS/perl; coreutils-only Linux ships sha256sum instead —
+     # resolve whichever exists so the verify never fails on a missing tool.
+     if command -v sha256sum >/dev/null 2>&1; then
+       actual_sha=$(sha256sum "$tmpfile" | awk '{print $1}')
+     else
+       actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     fi
      if [ "$actual_sha" != "$BUN_INSTALL_SHA" ]; then
        echo "ERROR: bun install script checksum mismatch" >&2
        echo "  expected: $BUN_INSTALL_SHA" >&2
diff --git a/pair-agent/SKILL.md b/pair-agent/SKILL.md
index fdd5eba80..2cc9df1c7 100644
--- a/pair-agent/SKILL.md
+++ b/pair-agent/SKILL.md
@@ -438,7 +438,13 @@ If `NEEDS_SETUP`:
      BUN_INSTALL_SHA="bab8acfb046aac8c72407bdcce903957665d655d7acaa3e11c7c4616beae68dd"
      tmpfile=$(mktemp)
      curl -fsSL "https://bun.sh/install" -o "$tmpfile"
-     actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     # shasum is macOS/perl; coreutils-only Linux ships sha256sum instead —
+     # resolve whichever exists so the verify never fails on a missing tool.
+     if command -v sha256sum >/dev/null 2>&1; then
+       actual_sha=$(sha256sum "$tmpfile" | awk '{print $1}')
+     else
+       actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     fi
      if [ "$actual_sha" != "$BUN_INSTALL_SHA" ]; then
        echo "ERROR: bun install script checksum mismatch" >&2
        echo "  expected: $BUN_INSTALL_SHA" >&2
diff --git a/qa-only/SKILL.md b/qa-only/SKILL.md
index 9de1cca6d..0de0aa3df 100644
--- a/qa-only/SKILL.md
+++ b/qa-only/SKILL.md
@@ -452,7 +452,13 @@ If `NEEDS_SETUP`:
      BUN_INSTALL_SHA="bab8acfb046aac8c72407bdcce903957665d655d7acaa3e11c7c4616beae68dd"
      tmpfile=$(mktemp)
      curl -fsSL "https://bun.sh/install" -o "$tmpfile"
-     actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     # shasum is macOS/perl; coreutils-only Linux ships sha256sum instead —
+     # resolve whichever exists so the verify never fails on a missing tool.
+     if command -v sha256sum >/dev/null 2>&1; then
+       actual_sha=$(sha256sum "$tmpfile" | awk '{print $1}')
+     else
+       actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     fi
      if [ "$actual_sha" != "$BUN_INSTALL_SHA" ]; then
        echo "ERROR: bun install script checksum mismatch" >&2
        echo "  expected: $BUN_INSTALL_SHA" >&2
diff --git a/setup-browser-cookies/SKILL.md b/setup-browser-cookies/SKILL.md
index 211d0d4c1..6e1895b35 100644
--- a/setup-browser-cookies/SKILL.md
+++ b/setup-browser-cookies/SKILL.md
@@ -197,7 +197,13 @@ If `NEEDS_SETUP`:
      BUN_INSTALL_SHA="bab8acfb046aac8c72407bdcce903957665d655d7acaa3e11c7c4616beae68dd"
      tmpfile=$(mktemp)
      curl -fsSL "https://bun.sh/install" -o "$tmpfile"
-     actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     # shasum is macOS/perl; coreutils-only Linux ships sha256sum instead —
+     # resolve whichever exists so the verify never fails on a missing tool.
+     if command -v sha256sum >/dev/null 2>&1; then
+       actual_sha=$(sha256sum "$tmpfile" | awk '{print $1}')
+     else
+       actual_sha=$(shasum -a 256 "$tmpfile" | awk '{print $1}')
+     fi
      if [ "$actual_sha" != "$BUN_INSTALL_SHA" ]; then
        echo "ERROR: bun install script checksum mismatch" >&2
        echo "  expected: $BUN_INSTALL_SHA" >&2