diff --git a/.github/actions/setup-rust-build-cache/tests/fixture.sh b/.github/actions/setup-rust-build-cache/tests/fixture.sh
index 019740f5..ecaf7d05 100755
--- a/.github/actions/setup-rust-build-cache/tests/fixture.sh
+++ b/.github/actions/setup-rust-build-cache/tests/fixture.sh
@@ -28,10 +28,9 @@ fi
 grep -Fxq 'fixture-id=417-1' "$WORK_DIR/seed/output" || fail 'seed does not export fixture identity'
 [[ "$(grep -c 'cargo build' "$ACTION_DIR/tests/assert-compiler-reuse.sh")" == 1 ]] || fail 'reuse probe primes its own cache'
 if grep -q 'cargo clean' "$ACTION_DIR/tests/assert-compiler-reuse.sh"; then fail 'reuse probe accepts same-job rebuilds'; fi
-workflow="$ACTION_DIR/../../workflows/deploy-action.yml"
+workflow="${CACHE_WORKFLOW_FILE:-$ACTION_DIR/../../workflows/deploy-action.yml}"
 seed=$(yq -r '.jobs."cache-restore-seed".steps[] | select(.name == "Seed native and WASM compiler outputs") | .run' "$workflow")
-# shellcheck disable=SC2016 # Assert the literal shell command in workflow metadata.
-[[ "$seed" == *'cargo build --locked --lib --target "$host"'* && "$seed" == *'cargo build --locked --lib --target wasm32-wasip1'* ]] || fail 'seed job does not compile both targets'
+[[ "$seed" == 'bash .github/actions/setup-rust-build-cache/tests/seed-compiler-cache.sh' ]] || fail 'seed does not verify compiler publication'
 for job in cache-restore-seed cache-restore-smoke cache-new-revision-smoke; do
   JOB_ID="$job" yq -e '.jobs[strenv(JOB_ID)].steps[] | select(.name == "Install native and WASM compiler targets") | .run == "bash .github/actions/setup-rust-build-cache/tests/setup-toolchain.sh"' "$workflow" >/dev/null || fail "$job does not share its Rust toolchain"
 done
@@ -41,7 +40,62 @@ for job in cache-restore-smoke cache-new-revision-smoke; do
   actual=$(JOB_ID="$job" yq -r '.jobs[strenv(JOB_ID)].steps[] | select(.id == "fixture") | .env.CACHE_FIXTURE_ID' "$workflow")
   [[ "$actual" == "$expected_identity" ]] || fail "$job does not reuse the seed fixture identity"
 done
-[[ "$(yq -r '.jobs."cache-restore-seed".steps[] | select(.id == "cache") | .with."save-target"' "$workflow")" == true ]] || fail 'seed does not opt into saving'
+[[ "$(yq -r '.jobs."cache-restore-seed".steps[] | select(.id == "cache") | .with."save-target"' "$workflow")" == false ]] || fail 'seed relies on unverified post-job saving'
+for job in fixture-release store-free-release; do
+  actual=$(JOB_ID="$job" yq -r '.jobs[strenv(JOB_ID)].needs // [] | length' "$workflow")
+  [[ "$actual" == 0 ]] || fail "$job depends on cache probe availability"
+done
+# Exercise both publication surfaces against their actual workflow wiring.
+for kind in source target; do
+  if [[ "$kind" == source ]]; then
+    expected_path=$(yq -r '.runs.steps[] | select(.id == "cargo-sources") | .with.path' "$ACTION_DIR/action.yml")
+  else
+    # shellcheck disable=SC2016 # Literal GitHub output reference.
+    expected_path='${{ steps.cache.outputs.cargo-target-dir }}'
+  fi
+  expected_key="\${{ steps.cache.outputs.$kind-cache-key }}"
+  retry_condition="steps.$kind-verify-1.outputs.cache-hit != 'true'"
+  for step in "$kind-save-1" "$kind-verify-1" "$kind-save-2" "$kind-verify-2"; do
+    actual=$(STEP_ID="$step" yq -r '.jobs."cache-restore-seed".steps[] | select(.id == strenv(STEP_ID)) | .with.path' "$workflow")
+    [[ "$actual" == "$expected_path" ]] || fail "$step uses a different cache path"
+    actual=$(STEP_ID="$step" yq -r '.jobs."cache-restore-seed".steps[] | select(.id == strenv(STEP_ID)) | .with.key' "$workflow")
+    [[ "$actual" == "$expected_key" ]] || fail "$step uses a different cache key"
+    actual=$(STEP_ID="$step" yq -r '.jobs."cache-restore-seed".steps[] | select(.id == strenv(STEP_ID)) | .if // ""' "$workflow")
+    if [[ "$step" == *-2 ]]; then
+      [[ "$actual" == "$retry_condition" ]] || fail "$step retries without a first-attempt miss"
+    else
+      [[ -z "$actual" ]] || fail "$step skips the initial publication attempt"
+    fi
+  done
+  for attempt in 1 2; do
+    STEP_ID="$kind-save-$attempt" yq -e '.jobs."cache-restore-seed".steps[] | select(.id == strenv(STEP_ID)) | .uses == "actions/cache/save@v5"' "$workflow" >/dev/null || fail 'missing explicit cache save'
+    STEP_ID="$kind-verify-$attempt" yq -e '.jobs."cache-restore-seed".steps[] | select(.id == strenv(STEP_ID)) | .with."lookup-only" == true' "$workflow" >/dev/null || fail 'cache publication is not verified'
+  done
+  STEP_ID="$kind-verify-2" yq -e '.jobs."cache-restore-seed".steps[] | select(.id == strenv(STEP_ID)) | .with."fail-on-cache-miss" == true' "$workflow" >/dev/null || fail 'exhausted publication retries stay green'
+  # The action can return successfully before honoring fail-on-cache-miss.
+  # Require actual exact-hit output, including when availability checks fail.
+  publication_step=".jobs.\"cache-restore-seed\".steps[] | select(.name == \"Require exact $kind seed publication\")"
+  publication_assertion=$(yq -r "$publication_step | .run" "$workflow")
+  [[ -n "$publication_assertion" && "$publication_assertion" != null ]] || fail 'missing exact publication assertion'
+  first_hit="\${{ steps.$kind-verify-1.outputs.cache-hit }}"
+  second_hit="\${{ steps.$kind-verify-2.outputs.cache-hit }}"
+  [[ "$(yq -r "$publication_step | .env.CACHE_SEED_FIRST_HIT" "$workflow")" == "$first_hit" ]] || fail 'publication assertion ignores first lookup output'
+  [[ "$(yq -r "$publication_step | .env.CACHE_SEED_SECOND_HIT" "$workflow")" == "$second_hit" ]] || fail 'publication assertion ignores second lookup output'
+  [[ "$(yq -r "$publication_step | .if // \"\"" "$workflow")" == '' ]] || fail 'publication assertion can be skipped after successful lookup steps'
+  [[ "$(yq -r "$publication_step | .\"continue-on-error\" // false" "$workflow")" == false ]] || fail 'publication assertion failure is ignored'
+  for first in '' false true partial; do
+    for second in '' false true partial; do
+      status=0
+      CACHE_SEED_FIRST_HIT="$first" CACHE_SEED_SECOND_HIT="$second" \
+        bash -e -o pipefail -c "$publication_assertion" >"$WORK_DIR/publication.log" 2>&1 || status=$?
+      if [[ "$first" == true || "$second" == true ]]; then
+        [[ "$status" == 0 ]] || fail 'publication assertion rejects a verified exact hit'
+      else
+        [[ "$status" != 0 ]] || fail "publication assertion accepts unverified outputs '$first'/'$second'"
+      fi
+    done
+  done
+done
 for job in fixture-release store-free-release; do
   actual=$(JOB_ID="$job" yq -r '.jobs[strenv(JOB_ID)].steps[] | select(.uses == "./.github/actions/setup-rust-build-cache") | .with."cache-target"' "$workflow")
   [[ "$actual" == false ]] || fail "$job enables full target caching for a disposable fixture"
diff --git a/.github/actions/setup-rust-build-cache/tests/publication.sh b/.github/actions/setup-rust-build-cache/tests/publication.sh
new file mode 100755
index 00000000..efee1326
--- /dev/null
+++ b/.github/actions/setup-rust-build-cache/tests/publication.sh
@@ -0,0 +1,62 @@
+#!/usr/bin/env bash
+# Mutate the workflow itself so contract checks cannot merely test a detached if.
+set -euo pipefail
+ACTION_DIR=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)
+WORK_DIR=$(mktemp -d "${TMPDIR:-/tmp}/edgezero-cache-publication-test.XXXXXX")
+trap 'rm -rf -- "$WORK_DIR"' EXIT
+# shellcheck source=common.sh
+source "$ACTION_DIR/tests/common.sh"
+workflow="$ACTION_DIR/../../workflows/deploy-action.yml"
+
+reject_mutation() {
+  local name="$1" expression="$2" diagnostic="$3" status=0
+  yq "$expression" "$workflow" >"$WORK_DIR/workflow.yml"
+  CACHE_WORKFLOW_FILE="$WORK_DIR/workflow.yml" bash "$ACTION_DIR/tests/fixture.sh" >"$WORK_DIR/log" 2>&1 || status=$?
+  [[ "$status" == 1 ]] || fail "workflow guard accepted mutation: $name (exit $status)"
+  grep -Fq "$diagnostic" "$WORK_DIR/log" || {
+    cat "$WORK_DIR/log" >&2
+    fail "mutation failed for an unrelated reason: $name"
+  }
+}
+
+for kind in source target; do
+  publication=".jobs.\"cache-restore-seed\".steps[] | select(.name == \"Require exact $kind seed publication\")"
+  reject_mutation 'missing final gate' \
+    ".jobs.\"cache-restore-seed\".steps |= map(select(.name != \"Require exact $kind seed publication\"))" \
+    'missing exact publication assertion'
+  reject_mutation 'hardcoded first hit' \
+    "($publication | .env.CACHE_SEED_FIRST_HIT) = \"true\"" \
+    'publication assertion ignores first lookup output'
+  reject_mutation 'hardcoded second hit' \
+    "($publication | .env.CACHE_SEED_SECOND_HIT) = \"true\"" \
+    'publication assertion ignores second lookup output'
+  reject_mutation 'skipped final gate' \
+    "($publication | .if) = \"false\"" \
+    'publication assertion can be skipped'
+  reject_mutation 'ignored final failure' \
+    "($publication | .\"continue-on-error\") = true" \
+    'publication assertion failure is ignored'
+  reject_mutation 'gate always succeeds' \
+    "($publication | .run) = \"true\"" \
+    'publication assertion accepts unverified outputs'
+  reject_mutation 'gate always fails' \
+    "($publication | .run) = \"false\"" \
+    'publication assertion rejects a verified exact hit'
+  for step in "$kind-save-1" "$kind-verify-1" "$kind-save-2" "$kind-verify-2"; do
+    for input in path key; do
+      reject_mutation "$step wrong $input" \
+        "(.jobs.\"cache-restore-seed\".steps[] | select(.id == \"$step\") | .with.$input) = \"wrong\"" \
+        "$step uses a different cache $input"
+    done
+    if [[ "$step" == *-2 ]]; then
+      reject_mutation "$step wrong retry condition" \
+        "(.jobs.\"cache-restore-seed\".steps[] | select(.id == \"$step\") | .if) = \"false\"" \
+        "$step retries without a first-attempt miss"
+    else
+      reject_mutation "$step skipped initial attempt" \
+        "(.jobs.\"cache-restore-seed\".steps[] | select(.id == \"$step\") | .if) = \"false\"" \
+        "$step skips the initial publication attempt"
+    fi
+  done
+done
+printf 'source and target publication workflow mutation contracts passed\n'
diff --git a/.github/actions/setup-rust-build-cache/tests/run.sh b/.github/actions/setup-rust-build-cache/tests/run.sh
index ba2af9eb..9f8fbcbf 100755
--- a/.github/actions/setup-rust-build-cache/tests/run.sh
+++ b/.github/actions/setup-rust-build-cache/tests/run.sh
@@ -143,3 +143,5 @@ printf 'setup-rust-build-cache action tests passed\n'
 bash "$ACTION_DIR/tests/revision.sh"
 bash "$ACTION_DIR/tests/review.sh"
 bash "$ACTION_DIR/tests/fixture.sh"
+bash "$ACTION_DIR/tests/publication.sh"
+bash "$ACTION_DIR/tests/seed.sh"
diff --git a/.github/actions/setup-rust-build-cache/tests/seed-compiler-cache.sh b/.github/actions/setup-rust-build-cache/tests/seed-compiler-cache.sh
new file mode 100755
index 00000000..487383d4
--- /dev/null
+++ b/.github/actions/setup-rust-build-cache/tests/seed-compiler-cache.sh
@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Publish each target before downstream jobs test first-build compiler reuse.
+fixture="${GITHUB_WORKSPACE:?}/cache-restore-fixture"
+target_dir=$(realpath "${CARGO_TARGET_DIR:?}")
+expected="$(realpath "${RUNNER_TEMP:?}")/edgezero-rust-cache/cache-restore-smoke-v2/target"
+[[ "$target_dir" == "$expected" ]] || {
+  printf '::error::compiler seed must use its confined fixture target directory\n' >&2
+  exit 1
+}
+cd "$fixture"
+host=$(rustc -vV | sed -n 's/^host: //p')
+[[ "$host" =~ ^[A-Za-z0-9_][A-Za-z0-9_.-]*$ ]] || {
+  printf '::error::rustc must report a safe host target component\n' >&2
+  exit 1
+}
+for target in "$host" wasm32-wasip1; do
+  for attempt in 1 2 3; do
+    # Cargo must call sccache again after a failed publication, rather than
+    # reporting locally fresh outputs as a successful cache seed.
+    debug_dir="$target_dir/$target/debug"
+    [[ ! -L "$target_dir/$target" && ! -L "$debug_dir" ]] || {
+      printf '::error::compiler seed cleanup must not follow target symlinks\n' >&2
+      exit 1
+    }
+    rm -rf -- "$debug_dir"
+    sccache --zero-stats
+    cargo build --locked --lib --target "$target"
+    stats=$(sccache --show-stats --stats-format json)
+    printf 'Compiler seed for %s (attempt %s): %s\n' "$target" "$attempt" "$stats"
+    if jq -e '((.stats.cache_hits.counts.Rust // 0) + (.stats.cache_writes // 0)) > 0 and (.stats.cache_errors.counts.Rust // 0) == 0 and (.stats.cache_read_errors // 0) == 0 and (.stats.cache_write_errors // 0) == 0' <<<"$stats" >/dev/null; then
+      break
+    fi
+    if [[ "$attempt" == 3 ]]; then
+      printf '::error::failed to publish compiler cache for %s after three attempts\n' "$target" >&2
+      exit 1
+    fi
+    printf '::warning::compiler cache seed failed; retrying after backoff\n'
+    sleep "$((attempt * 60))"
+  done
+done
diff --git a/.github/actions/setup-rust-build-cache/tests/seed.sh b/.github/actions/setup-rust-build-cache/tests/seed.sh
new file mode 100755
index 00000000..c939af2b
--- /dev/null
+++ b/.github/actions/setup-rust-build-cache/tests/seed.sh
@@ -0,0 +1,127 @@
+#!/usr/bin/env bash
+set -euo pipefail
+ACTION_DIR=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)
+WORK_DIR=$(mktemp -d "${TMPDIR:-/tmp}/edgezero-cache-seed-test.XXXXXX")
+trap 'rm -rf -- "$WORK_DIR"' EXIT
+# shellcheck source=common.sh
+source "$ACTION_DIR/tests/common.sh"
+mkdir -p "$WORK_DIR/bin" "$WORK_DIR/workspace/cache-restore-fixture" "$WORK_DIR/runner"
+export GITHUB_WORKSPACE="$WORK_DIR/workspace" RUNNER_TEMP="$WORK_DIR/runner"
+export CARGO_TARGET_DIR="$RUNNER_TEMP/edgezero-rust-cache/cache-restore-smoke-v2/target"
+export PROBE_LOG="$WORK_DIR/calls" PROBE_COUNT="$WORK_DIR/count"
+cat >"$WORK_DIR/bin/rustc" <<'MOCK'
+#!/usr/bin/env bash
+printf 'host: %s\n' "${PROBE_HOST:-test-host}"
+MOCK
+cat >"$WORK_DIR/bin/sleep" <<'MOCK'
+#!/usr/bin/env bash
+printf 'sleep %s\n' "$*" >>"$PROBE_LOG"
+MOCK
+cat >"$WORK_DIR/bin/cargo" <<'MOCK'
+#!/usr/bin/env bash
+printf 'build %s\n' "$*" >>"$PROBE_LOG"
+[[ "${PROBE_MODE:-}" != compile-failure ]] || exit 42
+[[ "$PROBE_MODE" != compile-wasm-failure || "${*: -1}" != wasm32-wasip1 ]] || exit 42
+[[ ! -d "$CARGO_TARGET_DIR/${*: -1}/debug" ]] || exit 43
+mkdir -p "$CARGO_TARGET_DIR/${*: -1}/debug"
+MOCK
+cat >"$WORK_DIR/bin/sccache" <<'MOCK'
+#!/usr/bin/env bash
+if [[ "$1" == --zero-stats ]]; then
+  printf 'zero\n' >>"$PROBE_LOG"
+  exit 0
+fi
+[[ "$1" == --show-stats ]] || exit 2
+count=$(cat "$PROBE_COUNT")
+printf '%s\n' "$((count + 1))" >"$PROBE_COUNT"
+if [[ "$PROBE_MODE" == permanent ||
+  ( "$PROBE_MODE" == transient && "$count" == 0 ) ||
+  ( "$PROBE_MODE" == wasm-transient && "$count" == 1 ) ||
+  ( "$PROBE_MODE" == both-transient && ( "$count" == 0 || "$count" == 2 ) ) ||
+  ( "$PROBE_MODE" == wasm-permanent && "$count" -ge 1 ) ]]; then
+  printf '{"stats":{"cache_write_errors":1,"cache_writes":0}}\n'
+elif [[ "$PROBE_MODE" == read-error ]]; then
+  printf '{"stats":{"cache_writes":1,"cache_read_errors":1}}\n'
+elif [[ "$PROBE_MODE" == compile-cache-error ]]; then
+  printf '{"stats":{"cache_hits":{"counts":{"Rust":1}},"cache_errors":{"counts":{"Rust":1}}}}\n'
+elif [[ "$PROBE_MODE" == malformed ]]; then
+  printf 'not-json\n'
+elif [[ "$PROBE_MODE" == empty ]]; then
+  printf '{"stats":{}}\n'
+elif [[ "$PROBE_MODE" == hit ]]; then
+  printf '{"stats":{"cache_hits":{"counts":{"Rust":1}}}}\n'
+else
+  printf '{"stats":{"cache_writes":1}}\n'
+fi
+MOCK
+chmod +x "$WORK_DIR/bin/"*
+export PATH="$WORK_DIR/bin:$PATH"
+run_seed() {
+  rm -rf "$CARGO_TARGET_DIR"
+  mkdir -p "$CARGO_TARGET_DIR"
+  printf '0\n' >"$PROBE_COUNT"
+  : >"$PROBE_LOG"
+  PROBE_MODE="$1" bash "$ACTION_DIR/tests/seed-compiler-cache.sh" >"$WORK_DIR/log" 2>&1
+}
+run_seed transient || fail 'compiler seed does not recover from a transient write failure'
+[[ "$(grep -c '^build ' "$PROBE_LOG")" == 3 ]] || fail 'retry does not rebuild fresh outputs'
+[[ "$(grep -c '^sleep ' "$PROBE_LOG")" == 1 ]] || fail 'transient error does not back off'
+run_seed hit || fail 'existing compiler hit is not accepted as published'
+[[ "$(grep -c '^build ' "$PROBE_LOG")" == 2 ]] || fail 'successful seed does not build both targets'
+grep -q -- '--target test-host$' "$PROBE_LOG" || fail 'successful seed omits native target'
+grep -q -- '--target wasm32-wasip1$' "$PROBE_LOG" || fail 'successful seed omits WASM target'
+[[ "$(grep -c '^zero$' "$PROBE_LOG")" == 2 ]] || fail 'successful seed does not reset stats for each target'
+for mode in wasm-transient both-transient; do
+  run_seed "$mode" || fail "$mode does not recover"
+  expected=3
+  if [[ "$mode" == both-transient ]]; then expected=4; fi
+  [[ "$(grep -c '^build ' "$PROBE_LOG")" == "$expected" ]] || fail "$mode does not rebuild every attempt"
+  [[ "$(grep -c '^zero$' "$PROBE_LOG")" == "$expected" ]] || fail "$mode does not reset every attempt"
+done
+for mode in permanent empty compile-failure compile-wasm-failure wasm-permanent read-error compile-cache-error malformed; do
+  if run_seed "$mode"; then fail "accepted unsuccessful compiler seeding: $mode"; fi
+  case "$mode" in
+    compile-failure) expected=1 ;;
+    compile-wasm-failure) expected=2 ;;
+    wasm-permanent) expected=4 ;;
+    *) expected=3 ;;
+  esac
+  [[ "$(grep -c '^build ' "$PROBE_LOG")" == "$expected" ]] || fail "$mode violates per-target retry limits"
+  [[ "$(grep -c '^zero$' "$PROBE_LOG")" == "$expected" ]] || fail "$mode uses stale stats"
+done
+# Cleanup must never follow restored symlinks outside the fixture root.
+for target in test-host wasm32-wasip1; do
+  for component in namespace debug; do
+    rm -rf -- "$CARGO_TARGET_DIR" "$WORK_DIR/outside"
+    mkdir -p "$CARGO_TARGET_DIR" "$WORK_DIR/outside/debug"
+    printf keep >"$WORK_DIR/outside/debug/marker"
+    if [[ "$component" == namespace ]]; then
+      ln -s "$WORK_DIR/outside" "$CARGO_TARGET_DIR/$target"
+    else
+      mkdir -p "$CARGO_TARGET_DIR/$target"
+      ln -s "$WORK_DIR/outside/debug" "$CARGO_TARGET_DIR/$target/debug"
+    fi
+    status=0
+    PROBE_MODE=hit bash "$ACTION_DIR/tests/seed-compiler-cache.sh" >"$WORK_DIR/log" 2>&1 || status=$?
+    [[ -f "$WORK_DIR/outside/debug/marker" ]] || fail "cleanup escaped through $target $component symlink"
+    [[ "$status" != 0 ]] || fail "accepted $target $component symlink"
+    grep -Fq 'compiler seed cleanup must not follow target symlinks' "$WORK_DIR/log" || fail 'symlink case failed for an unrelated reason'
+  done
+done
+rm -rf -- "$CARGO_TARGET_DIR"
+mkdir -p "$CARGO_TARGET_DIR" "$WORK_DIR/runner/edgezero-rust-cache/debug"
+printf keep >"$WORK_DIR/runner/edgezero-rust-cache/debug/marker"
+if PROBE_HOST=../.. PROBE_MODE=hit bash "$ACTION_DIR/tests/seed-compiler-cache.sh" >"$WORK_DIR/log" 2>&1; then
+  fail 'accepted traversal in compiler host'
+fi
+[[ -f "$WORK_DIR/runner/edgezero-rust-cache/debug/marker" ]] || fail 'removed output through host traversal'
+grep -Fq 'rustc must report a safe host target component' "$WORK_DIR/log" || fail 'traversal case failed for an unrelated reason'
+# A mistaken directory must never be removed by retry cleanup.
+export CARGO_TARGET_DIR="$WORK_DIR/outside"
+mkdir -p "$CARGO_TARGET_DIR"
+printf keep >"$CARGO_TARGET_DIR/marker"
+if PROBE_MODE=hit bash "$ACTION_DIR/tests/seed-compiler-cache.sh" >"$WORK_DIR/log" 2>&1; then
+  fail 'accepted unconfined compiler seed directory'
+fi
+[[ -f "$CARGO_TARGET_DIR/marker" ]] || fail 'removed unconfined output'
+printf 'compiler seed backoff contracts passed\n'
diff --git a/.github/workflows/deploy-action.yml b/.github/workflows/deploy-action.yml
index 15e797ce..bfb18d8d 100644
--- a/.github/workflows/deploy-action.yml
+++ b/.github/workflows/deploy-action.yml
@@ -138,7 +138,7 @@ jobs:
         with:
           app-name: cache-restore-smoke-v2
           cache-target: true
-          save-target: true
+          save-target: false
           target-cache-revision: ${{ steps.fixture.outputs.revision }}
           working-directory: cache-restore-fixture
 
@@ -149,12 +149,114 @@ jobs:
           printf '%s\n' 'edgezero-source-cache-smoke-v2' >"$HOME/.cargo/git/db/edgezero-source-cache-smoke-v2"
 
       - name: Seed native and WASM compiler outputs
-        working-directory: cache-restore-fixture
+        run: bash .github/actions/setup-rust-build-cache/tests/seed-compiler-cache.sh
+
+      # Sources otherwise save only in a warning-only post-job hook. Verify
+      # them before allowing the source-restore consumer to start. The combined
+      # action may later attempt an immutable duplicate save on an initial miss.
+      - name: Save seed source cache
+        id: source-save-1
+        uses: actions/cache/save@v5
+        with:
+          path: |
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+          key: ${{ steps.cache.outputs.source-cache-key }}
+      - name: Verify seed source publication
+        id: source-verify-1
+        uses: actions/cache/restore@v5
+        with:
+          path: |
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+          key: ${{ steps.cache.outputs.source-cache-key }}
+          lookup-only: true
+      - name: Back off before retrying source publication
+        if: steps.source-verify-1.outputs.cache-hit != 'true'
+        run: sleep 60
+      - name: Retry seed source cache save
+        id: source-save-2
+        if: steps.source-verify-1.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v5
+        with:
+          path: |
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+          key: ${{ steps.cache.outputs.source-cache-key }}
+      - name: Require seed source publication
+        id: source-verify-2
+        if: steps.source-verify-1.outputs.cache-hit != 'true'
+        uses: actions/cache/restore@v5
+        with:
+          path: |
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+          key: ${{ steps.cache.outputs.source-cache-key }}
+          lookup-only: true
+          fail-on-cache-miss: true
+
+      # Cache availability checks can return successfully before applying
+      # fail-on-cache-miss. Only an exact lookup hit establishes publication.
+      - name: Require exact source seed publication
+        env:
+          CACHE_SEED_FIRST_HIT: ${{ steps.source-verify-1.outputs.cache-hit }}
+          CACHE_SEED_SECOND_HIT: ${{ steps.source-verify-2.outputs.cache-hit }}
         run: |
-          host=$(rustc -vV | sed -n 's/^host: //p')
-          test -n "$host"
-          cargo build --locked --lib --target "$host"
-          cargo build --locked --lib --target wasm32-wasip1
+          if [[ "$CACHE_SEED_FIRST_HIT" != true && "$CACHE_SEED_SECOND_HIT" != true ]]; then
+            echo '::error::source seed was not verified with an exact cache hit after two attempts'
+            exit 1
+          fi
+
+      # Cache save warnings do not fail the action. Verify publication explicitly
+      # so a throttled seed cannot report success and fail both consumer jobs.
+      - name: Save seed target cache
+        id: target-save-1
+        uses: actions/cache/save@v5
+        with:
+          path: ${{ steps.cache.outputs.cargo-target-dir }}
+          key: ${{ steps.cache.outputs.target-cache-key }}
+      - name: Verify seed target publication
+        id: target-verify-1
+        uses: actions/cache/restore@v5
+        with:
+          path: ${{ steps.cache.outputs.cargo-target-dir }}
+          key: ${{ steps.cache.outputs.target-cache-key }}
+          lookup-only: true
+      - name: Back off before retrying target publication
+        if: steps.target-verify-1.outputs.cache-hit != 'true'
+        run: sleep 60
+      - name: Retry seed target cache save
+        id: target-save-2
+        if: steps.target-verify-1.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v5
+        with:
+          path: ${{ steps.cache.outputs.cargo-target-dir }}
+          key: ${{ steps.cache.outputs.target-cache-key }}
+      - name: Require seed target publication
+        id: target-verify-2
+        if: steps.target-verify-1.outputs.cache-hit != 'true'
+        uses: actions/cache/restore@v5
+        with:
+          path: ${{ steps.cache.outputs.cargo-target-dir }}
+          key: ${{ steps.cache.outputs.target-cache-key }}
+          lookup-only: true
+          fail-on-cache-miss: true
+
+      # Cache availability checks can return successfully before applying
+      # fail-on-cache-miss. Only an exact lookup hit establishes publication.
+      - name: Require exact target seed publication
+        env:
+          CACHE_SEED_FIRST_HIT: ${{ steps.target-verify-1.outputs.cache-hit }}
+          CACHE_SEED_SECOND_HIT: ${{ steps.target-verify-2.outputs.cache-hit }}
+        run: |
+          if [[ "$CACHE_SEED_FIRST_HIT" != true && "$CACHE_SEED_SECOND_HIT" != true ]]; then
+            echo '::error::target seed was not verified with an exact cache hit after two attempts'
+            exit 1
+          fi
 
   cache-restore-smoke:
     needs: cache-restore-seed