diff --git a/.github/scripts/fixtures/rust-ci-scope/collector.txt b/.github/scripts/fixtures/rust-ci-scope/collector.txt
new file mode 100644
index 000000000..9163f6cee
--- /dev/null
+++ b/.github/scripts/fixtures/rust-ci-scope/collector.txt
@@ -0,0 +1 @@
+rust_hft/tools/collector/src/polymarket/reference.rs
diff --git a/.github/scripts/fixtures/rust-ci-scope/control.txt b/.github/scripts/fixtures/rust-ci-scope/control.txt
new file mode 100644
index 000000000..b5e0e5c41
--- /dev/null
+++ b/.github/scripts/fixtures/rust-ci-scope/control.txt
@@ -0,0 +1 @@
+deployment/aliyun/polymarket-raw-ops-cutover.sh
diff --git a/.github/scripts/fixtures/rust-ci-scope/docs.txt b/.github/scripts/fixtures/rust-ci-scope/docs.txt
new file mode 100644
index 000000000..7efd40e02
--- /dev/null
+++ b/.github/scripts/fixtures/rust-ci-scope/docs.txt
@@ -0,0 +1 @@
+docs/reports/example.md
diff --git a/.github/scripts/fixtures/rust-ci-scope/live.txt b/.github/scripts/fixtures/rust-ci-scope/live.txt
new file mode 100644
index 000000000..01cca5318
--- /dev/null
+++ b/.github/scripts/fixtures/rust-ci-scope/live.txt
@@ -0,0 +1 @@
+rust_hft/apps/live/src/main.rs
diff --git a/.github/scripts/fixtures/rust-ci-scope/metadata.fixture b/.github/scripts/fixtures/rust-ci-scope/metadata.fixture
new file mode 100644
index 000000000..686a69b90
--- /dev/null
+++ b/.github/scripts/fixtures/rust-ci-scope/metadata.fixture
@@ -0,0 +1,14 @@
+{
+  "packages": [
+    { "name": "hft-collector", "manifest_path": "rust_hft/tools/collector/Cargo.toml", "dependencies": [] },
+    {
+      "name": "alpha-harness",
+      "manifest_path": "rust_hft/alpha-harness/app/Cargo.toml",
+      "dependencies": [{ "name": "hft-collector", "path": "rust_hft/tools/collector" }]
+    },
+    { "name": "hft-live", "manifest_path": "rust_hft/apps/live/Cargo.toml", "dependencies": [] },
+    { "name": "hft-integration", "manifest_path": "rust_hft/market-core/integration/Cargo.toml", "dependencies": [] },
+    { "name": "hft-data-adapter-ondo-perps", "manifest_path": "rust_hft/data-pipelines/adapters/adapter-ondo-perps/Cargo.toml", "dependencies": [] },
+    { "name": "hft-paper", "manifest_path": "rust_hft/apps/paper/Cargo.toml", "dependencies": [] }
+  ]
+}
diff --git a/.github/scripts/select-rust-ci-scope.sh b/.github/scripts/select-rust-ci-scope.sh
new file mode 100755
index 000000000..6c9495579
--- /dev/null
+++ b/.github/scripts/select-rust-ci-scope.sh
@@ -0,0 +1,184 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+event=${GITHUB_EVENT_NAME:-}
+base=
+head=HEAD
+changed_files=
+metadata=
+output=${GITHUB_OUTPUT:-/dev/stdout}
+
+while (($#)); do
+  case "$1" in
+    --event) event=$2; shift 2 ;;
+    --base) base=$2; shift 2 ;;
+    --head) head=$2; shift 2 ;;
+    --changed-files) changed_files=$2; shift 2 ;;
+    --metadata) metadata=$2; shift 2 ;;
+    --output) output=$2; shift 2 ;;
+    *) printf 'unknown argument: %s\n' "$1" >&2; exit 2 ;;
+  esac
+done
+
+loop=false
+handoff=false
+json=false
+ondo=false
+collector=false
+control=false
+focused=false
+toolchain=false
+
+select_all() {
+  loop=true
+  handoff=true
+  json=true
+  ondo=true
+  collector=true
+  control=true
+  focused=true
+  toolchain=true
+}
+
+emit() {
+  printf '%s\n' \
+    "loop=$loop" \
+    "handoff=$handoff" \
+    "json=$json" \
+    "ondo=$ondo" \
+    "collector=$collector" \
+    "control=$control" \
+    "focused=$focused" \
+    "toolchain=$toolchain" >>"$output"
+}
+
+# Branch pushes and manual runs retain the complete build/package contract.
+if [[ $event != pull_request ]]; then
+  select_all
+  emit
+  exit 0
+fi
+
+repo_root=$(git rev-parse --show-toplevel)
+declare -a paths=()
+if [[ -n $changed_files ]]; then
+  while IFS= read -r path; do paths+=("$path"); done <"$changed_files"
+else
+  [[ -n $base ]] || { printf '%s\n' '--base is required for pull requests' >&2; exit 2; }
+  while IFS= read -r -d '' path; do paths+=("$path"); done \
+    < <(git diff --no-renames --name-only --diff-filter=ACMRD -z "$base...$head")
+fi
+
+needs_metadata=false
+for path in "${paths[@]}"; do
+  case "$path" in
+    rust_hft/Cargo.toml|rust_hft/Cargo.lock|rust_hft/rust-toolchain*|rust_hft/.cargo/*|.cargo/*|.github/workflows/ci.yml|.github/scripts/select-rust-ci-scope.sh|.github/scripts/test-select-rust-ci-scope.sh|.github/scripts/fixtures/rust-ci-scope/*)
+      select_all
+      emit
+      exit 0
+      ;;
+    deployment/aliyun/*)
+      control=true
+      toolchain=true
+      ;;
+    rust_hft/*)
+      needs_metadata=true
+      ;;
+  esac
+done
+
+if [[ $needs_metadata == false ]]; then
+  emit
+  exit 0
+fi
+
+if [[ -z $metadata ]]; then
+  metadata=$(mktemp)
+  trap 'rm -f "$metadata"' EXIT
+  (cd "$repo_root/rust_hft" && cargo metadata --format-version 1 --no-deps --locked) >"$metadata"
+fi
+
+declare -a package_names=() package_dirs=() package_dependencies=()
+while IFS=$'\t' read -r name manifest dependencies; do
+  if [[ $manifest == "$repo_root/"* ]]; then manifest=${manifest#"$repo_root/"}; fi
+  package_names+=("$name")
+  package_dirs+=("${manifest%/Cargo.toml}")
+  package_dependencies+=("$dependencies")
+done < <(jq -r '.packages[] | [.name, .manifest_path, ([.dependencies[] | select(.path != null) | .name] | join(","))] | @tsv' "$metadata")
+
+affected=$'\n'
+is_affected() { [[ $affected == *$'\n'"$1"$'\n'* ]]; }
+mark_affected() { is_affected "$1" || affected+="$1"$'\n'; }
+
+for path in "${paths[@]}"; do
+  [[ $path == rust_hft/* ]] || continue
+  owner=
+  owner_length=0
+  for ((index = 0; index < ${#package_names[@]}; index++)); do
+    name=${package_names[$index]}
+    directory=${package_dirs[$index]}
+    if [[ $path == "$directory"/* && ${#directory} -gt $owner_length ]]; then
+      owner=$name
+      owner_length=${#directory}
+    fi
+  done
+  if [[ -z $owner || $owner == rust-hft-workspace ]]; then
+    select_all
+    emit
+    exit 0
+  fi
+  mark_affected "$owner"
+done
+
+# Cargo.toml remains the source of truth for downstream package impact.
+changed=true
+while [[ $changed == true ]]; do
+  changed=false
+  for ((index = 0; index < ${#package_names[@]}; index++)); do
+    name=${package_names[$index]}
+    is_affected "$name" && continue
+    dependency_list=${package_dependencies[$index]}
+    [[ -n $dependency_list ]] || continue
+    IFS=',' read -ra dependencies <<<"$dependency_list"
+    for dependency in "${dependencies[@]}"; do
+      if [[ -n $dependency ]] && is_affected "$dependency"; then
+        mark_affected "$name"
+        changed=true
+        break
+      fi
+    done
+  done
+done
+
+select_if_affected() {
+  local flag=$1
+  shift
+  local package
+  for package in "$@"; do
+    if is_affected "$package"; then
+      case "$flag" in
+        loop) loop=true ;;
+        handoff) handoff=true ;;
+        json) json=true ;;
+        ondo) ondo=true ;;
+        collector) collector=true ;;
+        focused) focused=true ;;
+      esac
+      toolchain=true
+      return
+    fi
+  done
+}
+
+select_if_affected loop alpha-domain alpha-store alpha-engine alpha-onnx-evaluator \
+  alpha-harness hft-harnessctl hft-research-ml
+select_if_affected handoff hft-live
+select_if_affected json hft-integration hft-data-adapter-binance hft-infra-redis hft-live
+select_if_affected ondo hft-data-adapter-ondo-perps hft-execution-adapter-ondo-perps hft-live
+select_if_affected collector hft-collector
+select_if_affected focused hft-live hft-paper hft-all-in-one
+
+# Collector source and its host controls are one release boundary.
+if [[ $collector == true ]]; then control=true; fi
+
+emit
diff --git a/.github/scripts/test-select-rust-ci-scope.sh b/.github/scripts/test-select-rust-ci-scope.sh
new file mode 100755
index 000000000..0a4e45b3e
--- /dev/null
+++ b/.github/scripts/test-select-rust-ci-scope.sh
@@ -0,0 +1,78 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+script_dir=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+selector="$script_dir/select-rust-ci-scope.sh"
+fixtures="$script_dir/fixtures/rust-ci-scope"
+tmp_dir=$(mktemp -d)
+trap 'rm -rf "$tmp_dir"' EXIT
+
+run_case() {
+  local name=$1 event=$2 changed=$3
+  local output="$tmp_dir/$name.out"
+  "$selector" --event "$event" --changed-files "$fixtures/$changed" \
+    --metadata "$fixtures/metadata.fixture" --output "$output"
+  printf '%s\n' "$output"
+}
+
+assert_flag() {
+  local output=$1 flag=$2 expected=$3
+  grep -qx "$flag=$expected" "$output" || {
+    printf '%s: expected %s=%s\n' "$output" "$flag" "$expected" >&2
+    cat "$output" >&2
+    exit 1
+  }
+}
+
+collector=$(run_case collector pull_request collector.txt)
+for flag in loop collector control toolchain; do assert_flag "$collector" "$flag" true; done
+for flag in handoff json ondo focused; do assert_flag "$collector" "$flag" false; done
+
+live=$(run_case live pull_request live.txt)
+for flag in handoff json ondo focused toolchain; do assert_flag "$live" "$flag" true; done
+for flag in loop collector control; do assert_flag "$live" "$flag" false; done
+
+control=$(run_case control pull_request control.txt)
+for flag in control toolchain; do assert_flag "$control" "$flag" true; done
+for flag in loop handoff json ondo collector focused; do assert_flag "$control" "$flag" false; done
+
+docs=$(run_case docs pull_request docs.txt)
+for flag in loop handoff json ondo collector control focused toolchain; do
+  assert_flag "$docs" "$flag" false
+done
+
+full=$(run_case full push collector.txt)
+for flag in loop handoff json ondo collector control focused toolchain; do
+  assert_flag "$full" "$flag" true
+done
+
+deletion_repo="$tmp_dir/deletion-repo"
+mkdir -p "$deletion_repo/rust_hft/tools/collector/src"
+git -C "$deletion_repo" init -q
+touch "$deletion_repo/rust_hft/tools/collector/src/removed.rs"
+git -C "$deletion_repo" add .
+git -C "$deletion_repo" -c user.name=CI -c user.email=ci@example.invalid commit -qm base
+deletion_base=$(git -C "$deletion_repo" rev-parse HEAD)
+rm "$deletion_repo/rust_hft/tools/collector/src/removed.rs"
+git -C "$deletion_repo" add -u
+git -C "$deletion_repo" -c user.name=CI -c user.email=ci@example.invalid commit -qm deletion
+deletion="$tmp_dir/deletion.out"
+(cd "$deletion_repo" && "$selector" --event pull_request --base "$deletion_base" \
+  --head HEAD --metadata "$fixtures/metadata.fixture" --output "$deletion")
+for flag in loop collector control toolchain; do assert_flag "$deletion" "$flag" true; done
+
+rename_repo="$tmp_dir/rename-repo"
+mkdir -p "$rename_repo/rust_hft/tools/collector/src" "$rename_repo/docs"
+git -C "$rename_repo" init -q
+touch "$rename_repo/rust_hft/tools/collector/src/moved.rs"
+git -C "$rename_repo" add .
+git -C "$rename_repo" -c user.name=CI -c user.email=ci@example.invalid commit -qm base
+rename_base=$(git -C "$rename_repo" rev-parse HEAD)
+git -C "$rename_repo" mv rust_hft/tools/collector/src/moved.rs docs/moved.rs
+git -C "$rename_repo" -c user.name=CI -c user.email=ci@example.invalid commit -qm rename
+rename="$tmp_dir/rename.out"
+(cd "$rename_repo" && "$selector" --event pull_request --base "$rename_base" \
+  --head HEAD --metadata "$fixtures/metadata.fixture" --output "$rename")
+for flag in loop collector control toolchain; do assert_flag "$rename" "$flag" true; done
+
+printf 'rust CI scope selector tests passed\n'
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1711b3cfc..50f06bc27 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,6 +1,7 @@
 name: Monorepo CI
 
 on:
+  workflow_dispatch:
   push:
     branches: [main, develop]
     paths-ignore:
@@ -32,6 +33,21 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Select Rust validation scope
+        id: scope
+        working-directory: .
+        env:
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          HEAD_SHA: ${{ github.event.pull_request.head.sha || github.sha }}
+        run: |
+          .github/scripts/test-select-rust-ci-scope.sh
+          .github/scripts/select-rust-ci-scope.sh \
+            --event "${{ github.event_name }}" \
+            --base "${BASE_SHA}" \
+            --head "${HEAD_SHA}"
 
       - name: Enforce Monday module layout
         working-directory: .
@@ -185,17 +201,21 @@ jobs:
           fi
 
       - name: Setup Rust toolchain
+        if: steps.scope.outputs.toolchain == 'true'
         uses: dtolnay/rust-toolchain@stable
         with:
           components: rustfmt, clippy
 
       - name: Install Linux build tools
+        if: steps.scope.outputs.toolchain == 'true'
         run: sudo apt-get update && sudo apt-get install -y clang mold protobuf-compiler shellcheck
 
       - name: Setup sccache
+        if: steps.scope.outputs.toolchain == 'true'
         uses: mozilla-actions/sccache-action@v0.0.10
 
       - name: Record cache dimensions
+        if: steps.scope.outputs.toolchain == 'true'
         id: cache-info
         shell: bash
         run: |
@@ -203,6 +223,7 @@ jobs:
           echo "sccache=$(${SCCACHE_PATH:-sccache} --version | awk '{print $2}')" >> "$GITHUB_OUTPUT"
 
       - name: Cache Rust
+        if: steps.scope.outputs.toolchain == 'true'
         uses: Swatinem/rust-cache@v2
         with:
           workspaces: |
@@ -212,6 +233,7 @@ jobs:
           save-if: ${{ github.event_name != 'pull_request' }}
 
       - name: Format Loop Engineer packages
+        if: steps.scope.outputs.loop == 'true'
         run: |
           cargo fmt --check --package alpha-domain
           cargo fmt --check --package alpha-store
@@ -222,9 +244,11 @@ jobs:
           cargo fmt --check --package hft-research-ml
 
       - name: Test Loop Engineer packages
+        if: steps.scope.outputs.loop == 'true'
         run: cargo test -p alpha-domain -p alpha-store -p alpha-engine -p alpha-onnx-evaluator -p alpha-harness -p hft-harnessctl -p hft-research-ml --locked
 
       - name: Verify signed runtime handoff
+        if: steps.scope.outputs.handoff == 'true'
         run: |
           cargo test -p hft-live --no-default-features --test deployment_envelope --locked
           cargo test -p hft-live --no-default-features --test deployment_artifacts --locked
@@ -232,6 +256,7 @@ jobs:
           cargo test -p hft-live --no-default-features --features formula-strategy,bitget --test deployment_artifacts --locked
 
       - name: Check JSON feature matrix
+        if: steps.scope.outputs.json == 'true'
         run: |
           cargo test -p hft-integration --no-default-features --locked
           cargo test -p hft-integration --no-default-features --features json-simd --locked
@@ -241,18 +266,21 @@ jobs:
           cargo check -p hft-live --features clickhouse,redis,grpc --locked
 
       - name: Verify Ondo Perps feature boundary
+        if: steps.scope.outputs.ondo == 'true'
         run: |
           cargo test -p hft-data-adapter-ondo-perps -p hft-execution-adapter-ondo-perps --locked
           cargo clippy -p hft-data-adapter-ondo-perps -p hft-execution-adapter-ondo-perps --all-targets --no-deps --locked -- -D warnings
           cargo check -p hft-live --features ondo-perps --locked
 
       - name: Verify governed data collector
+        if: steps.scope.outputs.collector == 'true'
         run: |
           cargo check -p hft-collector --locked
           cargo clippy -p hft-collector --all-targets --features collector-binance --no-deps --locked -- -D warnings
           cargo test -p hft-collector --features collector-binance --locked
 
       - name: Verify collector release control plane
+        if: steps.scope.outputs.control == 'true'
         run: |
           for script in ../deployment/aliyun/*.sh; do
             bash -n "$script"
@@ -265,6 +293,7 @@ jobs:
           cargo test -p hft-collector systemd_memory_envelope_covers_measured_polymarket_cold_start --locked
 
       - name: Build focused packages
+        if: steps.scope.outputs.focused == 'true'
         run: cargo build -p hft-live -p hft-paper -p hft-all-in-one -p alpha-harness -p hft-harnessctl --locked
 
       - name: Package binaries (if present)