diff --git a/.crow/auto-apply-patches.yaml b/.crow/auto-apply-patches.yaml
index b9c8697..0076353 100644
--- a/.crow/auto-apply-patches.yaml
+++ b/.crow/auto-apply-patches.yaml
@@ -45,7 +45,7 @@ steps:
       - git clone -q https://pat-s:$$REPO_RO_TOKEN@git.devxy.io/devxy/build-cran-binaries.git .
       - mkdir -p /mnt/cache/R-pkgs
       - rm -rf /mnt/cache/R-pkgs/00LOCK-*
-      - /opt/R/$R_VERSION/bin/R -q -e 'pak::pak(c("httr2", "jsonlite"))'
+      - UVR_R_BIN=/opt/R/$R_VERSION/bin/R local/uvr-install.sh httr2 jsonlite
       - /opt/R/$R_VERSION/bin/Rscript local/propose-patches.R --open-pr --limit $PATCH_LIMIT
     backend_options:
       kubernetes:
diff --git a/.crow/build-all-versions-install-deps.yaml b/.crow/build-all-versions-install-deps.yaml
index e0cca86..448cff3 100644
--- a/.crow/build-all-versions-install-deps.yaml
+++ b/.crow/build-all-versions-install-deps.yaml
@@ -10,22 +10,22 @@ variables:
       - arm64
     default: amd64
   OS:
-    description: "Base OS image name."
+    description: 'Base OS image name.'
     options:
       - alpine
       - redhat
       - ubuntu
     default: alpine
   OS_VERSION:
-    description: "OS image tag. Must match OS (alpine: 3.24; redhat: 8/9/10; ubuntu: jammy/noble)."
+    description: 'OS image tag. Must match OS (alpine: 3.24; redhat: 8/9/10; ubuntu: jammy/noble).'
     options:
-      - "3.24"
-      - "8"
-      - "9"
-      - "10"
-      - "jammy"
-      - "noble"
-    default: "3.24"
+      - '3.24'
+      - '8'
+      - '9'
+      - '10'
+      - 'jammy'
+      - 'noble'
+    default: '3.24'
   R_VERSION:
     description: 'Primary R version under /opt/R.'
     options:
@@ -66,23 +66,24 @@ steps:
         from_secret: B2_S3_SECRET_KEY
       PGPASS:
         from_secret: PGPASS
-      R_PKG_CACHE_DIR: /mnt/cache/pkgcache
       R_LIBS_USER: /mnt/cache/R-pkgs
+      # Keep uvr's downloads and extracted-package entries on the persistent
+      # volume instead of the container-local ~/.uvr default.
+      UVR_CACHE_DIR: /mnt/cache/uvr/cache
+      UVR_PACKAGES_DIR: /mnt/cache/uvr/packages
       CCACHE_DIR: /mnt/cache/ccache
     volumes:
       - ${ARCH}-binaries-r-dep-cache-${OS}-${OS_VERSION//./}:/mnt/cache
     commands:
       # one-time full wipe to fix corrupted .so files from previous failed builds
       # - rm -rf /mnt/cache/R-pkgs
-      # Clear churny pkgcache metadata left by a prior crashed run (the "patched"
-      # repo mints a new hash per PACKAGES change -> unbounded pkgs-*.rds/patched-*).
-      # Keep pkg/ downloads and the stable CRAN/BioC/INLA repo dirs.
-      - rm -rf /mnt/cache/pkgcache/R/pkgcache/_metadata/patched-* /mnt/cache/pkgcache/R/pkgcache/_metadata/pkgs-*.rds || true
-      - mkdir -p /mnt/cache/pkgcache /mnt/cache/R-pkgs /mnt/cache/ccache /mnt/cache/packages
+      - mkdir -p /mnt/cache/uvr/cache /mnt/cache/uvr/packages /mnt/cache/R-pkgs /mnt/cache/ccache /mnt/cache/packages
       - git clone -q https://pat-s:$$REPO_RO_TOKEN@git.devxy.io/devxy/build-cran-binaries.git .
       # Pin the same bincraft version the build steps use, so the precomputed
       # snapshot and the per-agent library stay consistent across the pipeline.
-      - /opt/R/$R_VERSION/bin/R -q -e 'pak::sysreqs_db_update(); source("local/install-bincraft.R"); pak::pak(c("RPostgres", "s3fs", "data.table", "future", "jsonlite")); packageVersion("bincraft")'
+      - /opt/R/$R_VERSION/bin/Rscript local/install-bincraft.R
+      - UVR_R_BIN=/opt/R/$R_VERSION/bin/R local/uvr-install.sh RPostgres s3fs data.table future jsonlite
+      - /opt/R/$R_VERSION/bin/R -q -e 'packageVersion("bincraft")'
       - /opt/R/$R_VERSION/bin/R -q -e "source('local/packages-to-build.R'); saveRDS(pkgs, '/mnt/cache/packages/pkgs_to_build.rds'); saveRDS(pkgs[r_minor_sensitive == TRUE], '/mnt/cache/packages/r_minor_sensitive_pkgs.rds'); sprintf('Precomputed %s package versions (%s r-minor-sensitive)', nrow(pkgs), nrow(pkgs[r_minor_sensitive == TRUE]))"
     backend_options:
       docker:
diff --git a/.crow/build-all-versions.yaml b/.crow/build-all-versions.yaml
index 3932811..9ab888a 100644
--- a/.crow/build-all-versions.yaml
+++ b/.crow/build-all-versions.yaml
@@ -11,25 +11,25 @@ variables:
       - arm64
     default: amd64
   OS:
-    description: "Base OS image name."
+    description: 'Base OS image name.'
     options:
       - alpine
       - redhat
       - ubuntu
     default: alpine
   OS_VERSION:
-    description: "OS image tag. Must match OS (alpine: 3.24; redhat: 8/9/10; ubuntu: jammy/noble)."
+    description: 'OS image tag. Must match OS (alpine: 3.24; redhat: 8/9/10; ubuntu: jammy/noble).'
     options:
-      - "3.22"
-      - "3.23"
-      - "3.24"
-      - "8"
-      - "9"
-      - "10"
-      - "jammy"
-      - "noble"
-      - "resolute"
-    default: "3.24"
+      - '3.22'
+      - '3.23'
+      - '3.24'
+      - '8'
+      - '9'
+      - '10'
+      - 'jammy'
+      - 'noble'
+      - 'resolute'
+    default: '3.24'
   R_VERSION:
     description: 'Primary R version under /opt/R.'
     options:
@@ -47,38 +47,49 @@ labels:
   platform: linux/${ARCH}
   group: rpkgs-${ARCH}
 
+# Empty UVR_CACHE_DIR/UVR_PACKAGES_DIR fall back to uvr's container-local
+# ~/.uvr defaults; amd64 deliberately does not persist them (as with the
+# pkgcache dir it replaces), arm64 does.
 matrix:
   include:
     - ARCH: amd64
-      R_PKG_CACHE_DIR: ''
+      UVR_CACHE_DIR: ''
+      UVR_PACKAGES_DIR: ''
       SPLIT_INTO: 4
       SPLIT_INDEX: 1
     - ARCH: amd64
-      R_PKG_CACHE_DIR: ''
+      UVR_CACHE_DIR: ''
+      UVR_PACKAGES_DIR: ''
       SPLIT_INTO: 4
       SPLIT_INDEX: 2
     - ARCH: amd64
-      R_PKG_CACHE_DIR: ''
+      UVR_CACHE_DIR: ''
+      UVR_PACKAGES_DIR: ''
       SPLIT_INTO: 4
       SPLIT_INDEX: 3
     - ARCH: amd64
-      R_PKG_CACHE_DIR: ''
+      UVR_CACHE_DIR: ''
+      UVR_PACKAGES_DIR: ''
       SPLIT_INTO: 4
       SPLIT_INDEX: 4
     - ARCH: arm64
-      R_PKG_CACHE_DIR: /mnt/cache/pkgcache
+      UVR_CACHE_DIR: /mnt/cache/uvr/cache
+      UVR_PACKAGES_DIR: /mnt/cache/uvr/packages
       SPLIT_INTO: 4
       SPLIT_INDEX: 1
     - ARCH: arm64
-      R_PKG_CACHE_DIR: /mnt/cache/pkgcache
+      UVR_CACHE_DIR: /mnt/cache/uvr/cache
+      UVR_PACKAGES_DIR: /mnt/cache/uvr/packages
       SPLIT_INTO: 4
       SPLIT_INDEX: 2
     - ARCH: arm64
-      R_PKG_CACHE_DIR: /mnt/cache/pkgcache
+      UVR_CACHE_DIR: /mnt/cache/uvr/cache
+      UVR_PACKAGES_DIR: /mnt/cache/uvr/packages
       SPLIT_INTO: 4
       SPLIT_INDEX: 3
     - ARCH: arm64
-      R_PKG_CACHE_DIR: /mnt/cache/pkgcache
+      UVR_CACHE_DIR: /mnt/cache/uvr/cache
+      UVR_PACKAGES_DIR: /mnt/cache/uvr/packages
       SPLIT_INTO: 4
       SPLIT_INDEX: 4
 
@@ -107,8 +118,10 @@ steps:
         from_secret: GITHUB_PAT
       # normal env vars
       GIT_USER: pat-s
-      # set the location of the 'pkgcache' cache dir which persists the R package dependencies needed to install the packages themselves
-      R_PKG_CACHE_DIR: ${R_PKG_CACHE_DIR}
+      # set the location of uvr's caches, which persist the R package
+      # dependencies needed to install the packages themselves
+      UVR_CACHE_DIR: ${UVR_CACHE_DIR}
+      UVR_PACKAGES_DIR: ${UVR_PACKAGES_DIR}
       R_LIBS_USER: /mnt/cache/R-pkgs
       CCACHE_DIR: /mnt/cache/ccache
       NCPUS: 2
@@ -116,12 +129,7 @@ steps:
       - ${ARCH}-binaries-r-dep-cache-${OS}-${OS_VERSION//./}:/mnt/cache
     commands:
       - git clone -q https://pat-s:$$REPO_RO_TOKEN@git.devxy.io/devxy/build-cran-binaries.git .
-      # Clear churny pkgcache metadata left by a prior crashed run (the "patched"
-      # repo mints a new hash per PACKAGES change -> unbounded pkgs-*.rds/patched-*).
-      # Keep pkg/ downloads and the stable CRAN/BioC/INLA repo dirs. Within-run
-      # growth is bounded separately by trim_pkgcache_metadata() in build-all.R.
-      - rm -rf /mnt/cache/pkgcache/R/pkgcache/_metadata/patched-* /mnt/cache/pkgcache/R/pkgcache/_metadata/pkgs-*.rds || true
-      - mkdir -p /mnt/cache/pkgcache /mnt/cache/R-pkgs /mnt/cache/ccache /mnt/cache/packages
+      - mkdir -p /mnt/cache/uvr/cache /mnt/cache/uvr/packages /mnt/cache/R-pkgs /mnt/cache/ccache /mnt/cache/packages
       # The primary pass must not rely on build-all-versions-install-deps having
       # run on *this* agent: depends_on only orders the steps, but the cache
       # volume is per-agent, so a job landing on an agent where install-deps did
diff --git a/.crow/process-updates.yaml b/.crow/process-updates.yaml
index 59b1c26..1e4833c 100644
--- a/.crow/process-updates.yaml
+++ b/.crow/process-updates.yaml
@@ -49,109 +49,109 @@ matrix:
       R_VERSION: 4.5.3
       IMG: alpine:3.22
       OS_ID: alpine322
-      PROCESS_NEW: "FALSE"
+      PROCESS_NEW: 'FALSE'
     - OS: alpine-322
       ARCH: arm64
       R_VERSION: 4.5.3
       IMG: alpine:3.23
       OS_ID: alpine322
-      PROCESS_NEW: "FALSE"
+      PROCESS_NEW: 'FALSE'
     - OS: alpine-323
       ARCH: amd64
       R_VERSION: 4.5.3
       IMG: alpine:3.23
       OS_ID: alpine323
-      PROCESS_NEW: "FALSE"
+      PROCESS_NEW: 'FALSE'
     - OS: alpine-323
       ARCH: arm64
       R_VERSION: 4.5.3
       IMG: alpine:3.23
       OS_ID: alpine323
-      PROCESS_NEW: "FALSE"
+      PROCESS_NEW: 'FALSE'
     - OS: alpine-324
       ARCH: amd64
       R_VERSION: 4.5.3
       IMG: alpine:3.24
       OS_ID: alpine324
-      PROCESS_NEW: "FALSE"
+      PROCESS_NEW: 'FALSE'
     - OS: alpine-324
       ARCH: arm64
       R_VERSION: 4.5.3
       IMG: alpine:3.24
       OS_ID: alpine324
-      PROCESS_NEW: "FALSE"
+      PROCESS_NEW: 'FALSE'
     - OS: redhat-8
       ARCH: amd64
       R_VERSION: 4.4.3
       IMG: redhat:8
       OS_ID: rhel8
-      PROCESS_NEW: "TRUE"
+      PROCESS_NEW: 'TRUE'
     - OS: redhat-8
       ARCH: arm64
       R_VERSION: 4.4.3
       IMG: redhat:8
       OS_ID: rhel8
-      PROCESS_NEW: "TRUE"
+      PROCESS_NEW: 'TRUE'
     - OS: redhat-9
       ARCH: amd64
       R_VERSION: 4.4.3
       IMG: redhat:9
       OS_ID: rhel9
-      PROCESS_NEW: "TRUE"
+      PROCESS_NEW: 'TRUE'
     - OS: redhat-9
       ARCH: arm64
       R_VERSION: 4.4.3
       IMG: redhat:9
       OS_ID: rhel9
-      PROCESS_NEW: "TRUE"
+      PROCESS_NEW: 'TRUE'
     - OS: redhat-10
       ARCH: amd64
       R_VERSION: 4.5.3
       IMG: redhat:10
       OS_ID: rhel10
-      PROCESS_NEW: "TRUE"
+      PROCESS_NEW: 'TRUE'
     - OS: redhat-10
       ARCH: arm64
       R_VERSION: 4.5.3
       IMG: redhat:10
       OS_ID: rhel10
-      PROCESS_NEW: "TRUE"
+      PROCESS_NEW: 'TRUE'
     - OS: ubuntu-2204
       ARCH: amd64
       R_VERSION: 4.4.3
       IMG: ubuntu:jammy
       OS_ID: jammy
-      PROCESS_NEW: "TRUE"
+      PROCESS_NEW: 'TRUE'
     - OS: ubuntu-2204
       ARCH: arm64
       R_VERSION: 4.4.3
       IMG: ubuntu:jammy
       OS_ID: jammy
-      PROCESS_NEW: "TRUE"
+      PROCESS_NEW: 'TRUE'
     - OS: ubuntu-2404
       ARCH: amd64
       R_VERSION: 4.4.3
       IMG: ubuntu:noble
       OS_ID: noble
-      PROCESS_NEW: "TRUE"
+      PROCESS_NEW: 'TRUE'
     - OS: ubuntu-2404
       ARCH: arm64
       R_VERSION: 4.4.3
       IMG: ubuntu:noble
       OS_ID: noble
-      PROCESS_NEW: "TRUE"
+      PROCESS_NEW: 'TRUE'
     - OS: ubuntu-2604
       ARCH: amd64
       R_VERSION: 4.5.3
       IMG: ubuntu:resolute
       OS_ID: resolute
-      PROCESS_NEW: "TRUE"
+      PROCESS_NEW: 'TRUE'
     - OS: ubuntu-2604
       ARCH: arm64
       R_VERSION: 4.5.3
       IMG: ubuntu:resolute
       OS_ID: resolute
-      PROCESS_NEW: "TRUE"
+      PROCESS_NEW: 'TRUE'
 
 steps:
   - name: 'Processing Updates'
@@ -182,8 +182,10 @@ steps:
       NTFY_AUTH: TRUE
       NTFY_PASSWORD:
         from_secret: ntfy_token
-      # set the location of the 'pkgcache' cache dir which persists the R package dependencies needed to install the packages themselves
-      R_PKG_CACHE_DIR: /mnt/cache/pkgcache
+      # set the location of uvr's caches, which persist the R package
+      # dependencies needed to install the packages themselves
+      UVR_CACHE_DIR: /mnt/cache/uvr/cache
+      UVR_PACKAGES_DIR: /mnt/cache/uvr/packages
       R_LIBS_USER: /mnt/cache/R-pkgs
       R_VERSION: ${R_VERSION}
       CCACHE_DIR: /mnt/cache/ccache
@@ -194,10 +196,10 @@ steps:
       INTERVAL: lubridate::interval(lubridate::today() - 6, lubridate::today() - 3)
     commands:
       - git clone -q https://pat-s:$$REPO_RO_TOKEN@git.devxy.io/devxy/build-cran-binaries.git .
-      - rm -rf /mnt/cache/R-pkgs/00LOCK-* /mnt/cache/R-pkgs/bincraft /mnt/cache/R-pkgs/pkgcache /mnt/cache/pkgcache/R/pkgcache
+      - rm -rf /mnt/cache/R-pkgs/00LOCK-* /mnt/cache/R-pkgs/bincraft
+      - mkdir -p /mnt/cache/uvr/cache /mnt/cache/uvr/packages /mnt/cache/R-pkgs /mnt/cache/ccache /mnt/cache/packages
       - /opt/R/$R_VERSION/bin/Rscript local/install-bincraft.R
       - /opt/R/$R_VERSION/bin/R -q -e 'packageVersion("bincraft")'
-      - mkdir -p /mnt/cache/pkgcache /mnt/cache/R-pkgs /mnt/cache/ccache /mnt/cache/packages
       # rhel-10 ships xwfb-run (Xwayland) instead of xvfb-run; prefer it and start weston, else fall back to xvfb-run
       - XVFB=$(command -v xwfb-run 2>/dev/null || command -v xvfb-run); XVFB_ARGS=""; if command -v xwfb-run >/dev/null 2>&1; then dnf install -y -q weston 2>/dev/null; XVFB_ARGS="-c weston"; fi
       # options(future.globals.onReference = NULL): for some reason s3fs::file_delete() throws 'Error: Detected a non-exportable reference ('externalptr') in one of the globals ('FUN' of class 'function') used in the future expression' otherwise
diff --git a/.crow/weekly-audit-missing.yaml b/.crow/weekly-audit-missing.yaml
index d66a37b..4efe409 100644
--- a/.crow/weekly-audit-missing.yaml
+++ b/.crow/weekly-audit-missing.yaml
@@ -142,7 +142,8 @@ steps:
       - git clone -q https://pat-s:$$REPO_RO_TOKEN@git.devxy.io/devxy/build-cran-binaries.git .
       - mkdir -p /mnt/cache/packages /mnt/cache/R-pkgs
       - rm -rf /mnt/cache/R-pkgs/00LOCK-*
-      - /opt/R/$R_VERSION/bin/R -q -e 'pak::pak(c("git::https://codefloe.com/rpkgs/bincraft.git", "httr2", "jsonlite"))'
+      - /opt/R/$R_VERSION/bin/Rscript local/install-bincraft.R
+      - UVR_R_BIN=/opt/R/$R_VERSION/bin/R local/uvr-install.sh httr2 jsonlite
       - /opt/R/$R_VERSION/bin/R -q -e 'source("local/weekly-missing-binaries-audit.R")'
     backend_options:
       docker:
diff --git a/.crow/weekly-patch-proposals.yaml b/.crow/weekly-patch-proposals.yaml
index 0284e93..027d41c 100644
--- a/.crow/weekly-patch-proposals.yaml
+++ b/.crow/weekly-patch-proposals.yaml
@@ -35,7 +35,7 @@ steps:
       - git clone -q https://pat-s:$$REPO_RO_TOKEN@git.devxy.io/devxy/build-cran-binaries.git .
       - mkdir -p /mnt/cache/R-pkgs
       - rm -rf /mnt/cache/R-pkgs/00LOCK-*
-      - /opt/R/$R_VERSION/bin/R -q -e 'pak::pak(c("httr2", "jsonlite"))'
+      - UVR_R_BIN=/opt/R/$R_VERSION/bin/R local/uvr-install.sh httr2 jsonlite
       - /opt/R/$R_VERSION/bin/Rscript local/propose-patches.R --open-issue
       - /opt/R/$R_VERSION/bin/Rscript local/proposal-tracking.R --open-issue
     backend_options:
diff --git a/.crow/weekly-rebuild-missing.yaml b/.crow/weekly-rebuild-missing.yaml
index 53f178f..03a13f9 100644
--- a/.crow/weekly-rebuild-missing.yaml
+++ b/.crow/weekly-rebuild-missing.yaml
@@ -141,7 +141,8 @@ steps:
       FORGEJO_TOKEN:
         from_secret: FORGEJO_TOKEN
       GIT_USER: pat-s
-      R_PKG_CACHE_DIR: /mnt/cache/pkgcache
+      UVR_CACHE_DIR: /mnt/cache/uvr/cache
+      UVR_PACKAGES_DIR: /mnt/cache/uvr/packages
       R_LIBS_USER: /mnt/cache/R-pkgs
       R_VERSION: ${R_VERSION}
       CCACHE_DIR: /mnt/cache/ccache
@@ -150,12 +151,12 @@ steps:
       NCPUS: 2
     commands:
       - git clone -q https://pat-s:$$REPO_RO_TOKEN@git.devxy.io/devxy/build-cran-binaries.git .
-      - mkdir -p /mnt/cache/pkgcache /mnt/cache/R-pkgs /mnt/cache/ccache /mnt/cache/packages
+      - mkdir -p /mnt/cache/uvr/cache /mnt/cache/uvr/packages /mnt/cache/R-pkgs /mnt/cache/ccache /mnt/cache/packages
       - rm -rf /mnt/cache/R-pkgs/00LOCK-*
       - /opt/R/$R_VERSION/bin/Rscript local/install-bincraft.R
       - /opt/R/$R_VERSION/bin/R -q -e 'packageVersion("bincraft")'
       - XVFB=$(command -v xwfb-run 2>/dev/null || command -v xvfb-run); XVFB_ARGS=""; if command -v xwfb-run >/dev/null 2>&1; then dnf install -y -q weston 2>/dev/null; XVFB_ARGS="-c weston"; fi
-      - /opt/R/$R_VERSION/bin/R -q -e 'pak::pak("httr2")'
+      - UVR_R_BIN=/opt/R/$R_VERSION/bin/R local/uvr-install.sh httr2
       - /opt/R/$R_VERSION/bin/R -q -e 'source("local/fetch-rebuild-packages-from-issue.R")'
       - $XVFB $XVFB_ARGS -- /opt/R/$R_VERSION/bin/R -q -e "sink(stdout(), type = 'message'); options(crayon.enabled = TRUE, Ncpus = $NCPUS, future.globals.onReference = NULL); pkgs <- readLines('/tmp/rebuild_pkgs.txt'); if (length(pkgs) == 0) { cat('Nothing to rebuild\n'); q('no') }; excluded <- jsonlite::fromJSON('local/excluded-packages.json')[['package']]; pkgs <- setdiff(pkgs, excluded); cat(sprintf('Rebuilding %d packages\n', length(pkgs))); n <- length(pkgs); for (i in seq_along(pkgs)) { x <- pkgs[i]; cat(sprintf('[%d/%d] %s\n', i, n, x)); tryCatch(bincraft::build_binary_package(x, tag_limit = 1L, patches = 'local/patches', s3_endpoint = 'https://s3.eu-central-003.backblazeb2.com', s3_region = 'eu-central-003', s3_bucket = 'devxy-rpkgs-binaries', s3_access_key_id = Sys.getenv('B2_S3_ACCESS_KEY'), s3_secret_access_key = Sys.getenv('B2_S3_SECRET_KEY'), metadata_db_host = 'r-binaries.devxy.io', metadata_db_name = 'build_metadata', metadata_db_table = 'single_builds', metadata_db_user = 'rpkgs', metadata_db_password = Sys.getenv('PGPASS'), metadata_db_sslmode = 'require', metadata_db_port = 15432, archive = TRUE, upload = TRUE, store_build_metadata = TRUE), error = function(e) cat(sprintf('ERROR building %s - %s\n', x, conditionMessage(e)))) }" 2>&1
     backend_options:
diff --git a/README.md b/README.md
index 538df34..989069e 100644
--- a/README.md
+++ b/README.md
@@ -112,9 +112,9 @@ Processing updates with an existing database file takes around 5 minutes.
 
 ### Inferring System Dependencies
 
-R package dependencies and their system dependencies are installed through {pak}.
-{pak} allows for parallel downloads and installation, significantly speeding up package installation compared to `install.packages()`.
-Additionally, it automatically infers package dependencies using JSON rules from [rstudio/r-system-requirements](https://github.com/rstudio/r-system-requirements).
+R package dependencies and their system dependencies are installed through [uvr](https://github.com/nbafrank/uvr).
+`uvr` allows for parallel downloads and installation, significantly speeding up package installation compared to `install.packages()`.
+Additionally, it automatically infers package dependencies using JSON rules vendored from [rstudio/r-system-requirements](https://github.com/rstudio/r-system-requirements).
 Not all R packages specify required system dependencies in their DESCRIPTION file, and not all listed dependencies have existing rules in `rstudio/r-system-requirements`.
 For Alpine, no rules existed until recently, establishing a foundation for semi-automated package installation on Alpine Linux.
 
@@ -152,12 +152,13 @@ A Shiny dashboard providing a search functionality of the database and grouped s
 
 Is supported by writing `Meta/archive.rds` during each package index update, listing all available archived packages.
 
-### `pak::pak(package@version)`
+### `uvr add package@version`
 
-`pak` searches for `Archive/<package>` and can install all versions it finds.
+Clients that resolve archived versions search for `Archive/<package>` and can install all versions they find.
+This holds for `uvr` as well as for older `pak`-based clients.
 
 Ensure to use a clean cache if other repositories have been used previously.
-If in doubt or when testing, call `pak::meta_clean(force = TRUE)`.
+If in doubt or when testing, call `uvr cache clean`.
 
 ## Lessons Learned
 
@@ -180,7 +181,7 @@ If in doubt or when testing, call `pak::meta_clean(force = TRUE)`.
 
 ## URL Composition and Platform Identifiers
 
-Platform identifiers have been aligned with those used in <https://github.com/rstudio/r-system-requirements> to ensure proper recognition by the automatic syslib dependency installer of `pak`, specifically via the environment variable `PKG_SYSREQS_PLATFORM`:
+Platform identifiers have been aligned with those used in <https://github.com/rstudio/r-system-requirements>, which `uvr` vendors and uses for its automatic syslib dependency installer (`uvr sync --install-system-deps`):
 
 - redhat-9
 - redhat-8
@@ -237,8 +238,8 @@ internal error 1 in memDecompress
 Solution:
 
 ```sh
-rm -rf  /mnt/cache/R-pkgs/pak /mnt/cache/pkgcache/ /root/.cache/R/
-R -q -e 'install.packages("pak", repos = sprintf("https://r-lib.github.io/p/pak/stable/%s/%s/%s", .Platform$pkgType, R.Version()$os, R.Version()$arch))'
+uvr cache clean
+rm -rf /mnt/cache/uvr /root/.cache/R/
 ```
 
 </details>
diff --git a/build-all-versions-install-deps.yaml b/build-all-versions-install-deps.yaml
index 926d550..dd02e8a 100644
--- a/build-all-versions-install-deps.yaml
+++ b/build-all-versions-install-deps.yaml
@@ -30,8 +30,9 @@
 #         from_secret: HETZNER_S3_SECRET_KEY_K3S
 #       # normal env vars
 #       GIT_USER: pat-s
-#       # set the location of the 'pkgcache' cache dir which persists the R package dependencies needed to install the packages themselves
-#       # R_PKG_CACHE_DIR: /mnt/cache/pkgcache
+#       # set the location of uvr's caches, which persist the R package dependencies needed to install the packages themselves
+#       # UVR_CACHE_DIR: /mnt/cache/uvr/cache
+#       # UVR_PACKAGES_DIR: /mnt/cache/uvr/packages
 #       R_LIBS_USER: /mnt/cache/R-pkgs
 #       CCACHE_DIR: /mnt/cache/ccache
 #     volumes:
@@ -39,9 +40,8 @@
 #     commands:
 #       - git clone -q https://pat-s:$$REPO_RO_TOKEN@git.devxy.io/devxy/build-cran-binaries.git .
 #       - mkdir -p /mnt/cache/R-pkgs
-#       - rm -rf /mnt/cache/R-pkgs/00LOCK-* /mnt/cache/R-pkgs/bincraft /mnt/cache/pkgcache
-#       - /opt/R/$R_VERSION/bin/R -q -e 'install.packages("pak", repos = sprintf("https://r-lib.github.io/p/pak/stable/%s/%s/%s", .Platform$pkgType, R.Version()$os, R.Version()$arch))'
-#       - /opt/R/$R_VERSION/bin/R -q -e 'pak::pak("git::https://codefloe.com/rpkgs/bincraft.git", dependencies = TRUE)'
+#       - rm -rf /mnt/cache/R-pkgs/00LOCK-* /mnt/cache/R-pkgs/bincraft /mnt/cache/uvr
+#       - UVR_R_BIN=/opt/R/$R_VERSION/bin/R local/uvr-install.sh forgejo::codefloe.com/rpkgs/bincraft
 #       - /opt/R/$R_VERSION/bin/R -q -e 'packageVersion("bincraft")'
 #       # - /opt/R/$R_VERSION/bin/R -q -e "future::plan('multisession', workers = 6L); pkgs = bincraft::query_packages_without_historic_versions('alpine322', 'amd64'); saveRDS(pkgs, '/mnt/cache/pkgs_amd64.rds')"
 #       - /opt/R/$R_VERSION/bin/R -q -e "future::plan('multisession', workers = 6L); pkgs = bincraft::query_packages_without_historic_versions('alpine323', 'arm64'); saveRDS(pkgs, '/mnt/cache/pkgs_arm64.rds')"
diff --git a/docker/Containerfile-shiny-app b/docker/Containerfile-shiny-app
index 7c7994f..4b0bd6c 100644
--- a/docker/Containerfile-shiny-app
+++ b/docker/Containerfile-shiny-app
@@ -1,7 +1,15 @@
 FROM devxygmbh/r-alpine:4.4-3.20 AS build
 
 # ARG GITHUB_PAT
-RUN R -q -e 'install.packages("pak", repos = sprintf("https://r-lib.github.io/p/pak/stable/%s/%s/%s", .Platform$pkgType, R.Version()$os, R.Version()$arch))'
+RUN apk add --no-cache curl ca-certificates \
+  && curl -fsSL https://raw.githubusercontent.com/nbafrank/uvr/main/install.sh \
+    | UVR_INSTALL_DIR=/usr/local/bin sh
+
+# One uvr project drives both dependency installs below. UVR_LIBRARY points the
+# syncs at the image's R library instead of the project-local .uvr/library/, so
+# `Rscript app.R` finds the packages without a uvr-aware .Rprofile.
+ENV UVR_LIBRARY=/usr/lib/R/library
+RUN mkdir -p /uvr && cd /uvr && uvr init --here
 
 COPY --link ./DESCRIPTION .
 COPY --link ./R ./R
@@ -11,13 +19,19 @@ COPY --link ./shiny/app.R /app/app.R
 
 RUN ls -la
 
-# install R package deps
-RUN R -q -e 'pak::pak()'
+# install R package deps. uvr has no equivalent of bare `pak::pak()`, which
+# reads the DESCRIPTION in the working directory, so extract the dependency
+# names and hand them to `uvr add`.
+RUN R -q --no-echo -e "d <- read.dcf('DESCRIPTION'); f <- intersect(colnames(d), c('Depends', 'Imports', 'LinkingTo')); p <- trimws(sub('[(].*', '', unlist(strsplit(paste(d[, f], collapse = ','), ',')))); writeLines(setdiff(p[nzchar(p)], c('R', rownames(installed.packages()))), '/tmp/deps.txt')" \
+  && cd /uvr && xargs -r uvr add --no-install < /tmp/deps.txt \
+  && uvr sync --install-system-deps
 
 RUN R CMD INSTALL --no-docs --without-keep.source  .
 
 # install shiny app deps
-RUN R -q -e "install.packages('renv'); pkgs <- renv::dependencies('/app/app.R')[['Package']]; pkgs = setdiff(pkgs, 'bincraft'); pak::pak(pkgs)"
+RUN R -q -e "install.packages('renv'); pkgs <- renv::dependencies('/app/app.R')[['Package']]; pkgs = setdiff(pkgs, 'bincraft'); writeLines(pkgs, '/tmp/app-deps.txt')" \
+  && cd /uvr && xargs -r uvr add --no-install < /tmp/app-deps.txt \
+  && uvr sync --install-system-deps
 
 ENV PGPASS=""
 
diff --git a/docker/build-one.Dockerfile b/docker/build-one.Dockerfile
index 5bc107a..8e61ebd 100644
--- a/docker/build-one.Dockerfile
+++ b/docker/build-one.Dockerfile
@@ -17,7 +17,10 @@ ARG CACHEBUST
 WORKDIR /work
 COPY build-one.R /work/build-one.R
 # Resolve and install the latest bincraft release dynamically (no hardcoded pin).
+# uvr-install.sh lands under /work/local/ because install-bincraft.R looks for it
+# there when the working directory is not a repo checkout.
 COPY install-bincraft.R /work/install-bincraft.R
+COPY uvr-install.sh /work/local/uvr-install.sh
 # Ship the patch registry so build-one.R's `patches = "local/patches"` resolves
 # (build context is `local/`, CWD is /work).
 COPY patches /work/local/patches
diff --git a/docker/reprex/alpine.sh b/docker/reprex/alpine.sh
index 94806e5..851a9cc 100644
--- a/docker/reprex/alpine.sh
+++ b/docker/reprex/alpine.sh
@@ -1,10 +1,14 @@
 docker run --rm -it --platform linux/arm64 alpine sh
 
-apk add --no-cache R R-dev g++
+apk add --no-cache R R-dev g++ curl ca-certificates
 
-R -q -e 'install.packages("pak", repos = sprintf("https://r-lib.github.io/p/pak/devel/%s/%s/%s", .Platform$pkgType, R.Version()$os, R.Version()$arch))'
+curl -fsSL https://raw.githubusercontent.com/nbafrank/uvr/main/install.sh | UVR_INSTALL_DIR=/usr/local/bin sh
 
-R -q -e 'pak::pak(c("gert", "purrr"))'
+# `uvr add` always writes to .uvr/library/; only `uvr sync` honours UVR_LIBRARY,
+# so add without installing and let the sync place the packages.
+export UVR_LIBRARY=/usr/lib/R/library
+mkdir -p /uvr && cd /uvr && uvr init --here
+uvr add --no-install gert purrr && uvr sync --install-system-deps
 
 R
 
@@ -22,14 +26,20 @@ unlink(sprintf("%s/%s", tempdir(), "tmp1"), force = TRUE, recursive = TRUE)
 tag <- all_tags$name
 package_name <- rep(package_name, length(tag))
 
+# uvr has no `pak::local_install_deps()`; read the DESCRIPTION of the checkout
+# and `uvr add` the dependency names instead.
 purrr::walk2(package_name[1], tag, \(x, y) {
   print(y)
   system("git config --global advice.detachedHead false")
+  src <- sprintf("/tmp/%s_%s", x[1], y)
   system2("git", args = c(
     "clone", "-q", sprintf("--branch=%s", tail(y, 1)),
-    sprintf("https://github.com/cran/%s", x[1]), sprintf("/tmp/%s_%s", x[1], y)
+    sprintf("https://github.com/cran/%s", x[1]), src
   ))
-  pak::local_install_deps(sprintf("/tmp/%s_%s", x[1], y))
+  d <- read.dcf(file.path(src, "DESCRIPTION"))
+  f <- intersect(colnames(d), c("Depends", "Imports", "LinkingTo"))
+  deps <- trimws(sub("[(].*", "", unlist(strsplit(paste(d[, f], collapse = ","), ","))))
+  deps <- setdiff(deps[nzchar(deps)], "R")
+  system2("uvr", c("add", "--no-install", deps))
+  system2("uvr", c("sync", "--install-system-deps"))
 })
-
-
diff --git a/local/build-all.R b/local/build-all.R
index 1df1f83..37fc593 100644
--- a/local/build-all.R
+++ b/local/build-all.R
@@ -27,7 +27,9 @@ package_cache_files <- c(
   "/mnt/cache/packages/s3_cache.rds"
 )
 if (!all(file.exists(package_cache_files))) {
-  message("Package snapshot missing from cache; recomputing via packages-to-build.R")
+  message(
+    "Package snapshot missing from cache; recomputing via packages-to-build.R"
+  )
   dir.create("/mnt/cache/packages", showWarnings = FALSE, recursive = TRUE)
   save_rds_atomic <- function(obj, path) {
     tmp <- paste0(path, ".tmp.", Sys.getpid())
@@ -36,7 +38,10 @@ if (!all(file.exists(package_cache_files))) {
   }
   source(file.path("local", "packages-to-build.R"))
   save_rds_atomic(pkgs, "/mnt/cache/packages/pkgs_to_build.rds")
-  save_rds_atomic(pkgs[r_minor_sensitive == TRUE], "/mnt/cache/packages/r_minor_sensitive_pkgs.rds")
+  save_rds_atomic(
+    pkgs[r_minor_sensitive == TRUE],
+    "/mnt/cache/packages/r_minor_sensitive_pkgs.rds"
+  )
   message("Package snapshot recomputed.")
 }
 
@@ -112,20 +117,22 @@ built <- DBI::dbGetQuery(
 )
 DBI::dbDisconnect(con)
 before <- nrow(chunk)
-chunk <- chunk[!paste(chunk$Package, chunk$Version) %in% paste(built$name, built$tag), ]
-sprintf("Skipped %d already-attempted package versions; %d remaining for this job", before - nrow(chunk), nrow(chunk))
+chunk <- chunk[
+  !paste(chunk$Package, chunk$Version) %in% paste(built$name, built$tag),
+]
+sprintf(
+  "Skipped %d already-attempted package versions; %d remaining for this job",
+  before - nrow(chunk),
+  nrow(chunk)
+)
 
 # Read pre-computed S3 listing from install-deps step
 # This avoids loading s3fs/reticulate/Python in the build container,
-# saving significant memory for pak subprocess forks
+# saving significant memory for the dependency-installer subprocesses
 s3_cache <- readRDS("/mnt/cache/packages/s3_cache.rds")
 sprintf("S3 cache: %s files", length(s3_cache))
 
 n <- nrow(chunk)
-# Every `trim_every` packages, bound the pkgcache _metadata dir so a full-platform
-# run does not accumulate thousands of ~70 MB snapshots and fill the host disk.
-# No-op on amd64 (R_PKG_CACHE_DIR is empty / cache not persisted).
-trim_every <- 25L
 mapply(
   function(pkg, ver, sens, i) {
     cat(sprintf("[%d/%d] %s_%s (r_minor_sensitive=%s)\n", i, n, pkg, ver, sens))
@@ -151,12 +158,6 @@ mapply(
       upload = TRUE,
       store_build_metadata = TRUE
     )
-    if (i %% trim_every == 0L) {
-      removed <- trim_pkgcache_metadata()
-      if (removed > 0L) {
-        cat(sprintf("  [pkgcache trim] removed %d stale _metadata entries\n", removed))
-      }
-    }
   },
   chunk$Package,
   chunk$Version,
diff --git a/local/install-bincraft.R b/local/install-bincraft.R
index 4665b3b..e39cb4f 100644
--- a/local/install-bincraft.R
+++ b/local/install-bincraft.R
@@ -11,10 +11,11 @@
 #
 # How it works: list the remote tags with `git ls-remote` (no token needed for
 # the public repo), keep the `vX.Y.Z` release tags, pick the highest version,
-# and install it with pak. pak is idempotent on the git ref, so re-running keeps
-# the package when it is already current and only updates when a newer tag ships.
-# Filtering/sorting is done in R (not via git's `--sort`/refspec) so behaviour is
-# identical across git versions and `system2()` argument handling.
+# and install it with uvr via `local/uvr-install.sh`. uvr is idempotent on the
+# git ref, so re-running keeps the package when it is already current and only
+# updates when a newer tag ships. Filtering/sorting is done in R (not via git's
+# `--sort`/refspec) so behaviour is identical across git versions and
+# `system2()` argument handling.
 
 repo_url <- Sys.getenv(
   "BINCRAFT_GIT_URL",
@@ -44,7 +45,43 @@ latest <- tags[order(package_version(sub("^v", "", tags)), decreasing = TRUE)][
 ]
 
 message(sprintf("Installing latest bincraft release: %s", latest))
-pak::pak(sprintf("git::%s@%s", repo_url, latest))
+
+# uvr addresses Forgejo repos as `forgejo::host/owner/repo@ref` rather than as a
+# git URL, so drop the scheme and the trailing `.git` from `repo_url`.
+spec <- sprintf(
+  "forgejo::%s@%s",
+  sub("\\.git$", "", sub("^[a-z]+://", "", repo_url)),
+  latest
+)
+
+# `local/uvr-install.sh` when run from the repo root, `/work/local/` in the
+# build-one image, which copies the two scripts into a flatter layout.
+helper <- Sys.getenv("UVR_INSTALL_SH", unset = "")
+if (!nzchar(helper)) {
+  candidates <- c("local/uvr-install.sh", "/work/local/uvr-install.sh")
+  found <- candidates[file.exists(candidates)]
+  if (length(found) == 0L) {
+    stop("Could not locate uvr-install.sh; set UVR_INSTALL_SH", call. = FALSE)
+  }
+  helper <- found[1L]
+}
+
+# Point uvr at the R running this script and at the library it would install
+# into, so the per-R-minor passes in the build pipelines (which call a different
+# Rscript with R_LIBS_USER pointed elsewhere) target their own R and library.
+Sys.setenv(
+  UVR_R_BIN = file.path(R.home("bin"), "R"),
+  UVR_TARGET_LIB = .libPaths()[1L]
+)
+
+status <- system2(helper, shQuote(spec))
+if (!identical(status, 0L)) {
+  stop(
+    sprintf("uvr failed to install %s (exit %s)", spec, status),
+    call. = FALSE
+  )
+}
+
 message(sprintf(
   "bincraft %s installed (%s)",
   as.character(utils::packageVersion("bincraft")),
diff --git a/local/packages-to-build.R b/local/packages-to-build.R
index 7a3652d..887952d 100644
--- a/local/packages-to-build.R
+++ b/local/packages-to-build.R
@@ -15,15 +15,15 @@ suppressPackageStartupMessages(library(data.table))
 # Sys.setenv("OS_VERSION" = "3.22")
 # Sys.setenv("ARCH" = "arm64")
 
-arch = Sys.getenv("ARCH")
+arch <- Sys.getenv("ARCH")
 # target: alpine-322, ubuntu-2404, redhat-9, etc.
-platform = paste(
+platform <- paste(
   Sys.getenv("OS"),
   gsub("[.]", "", Sys.getenv("OS_VERSION")),
   sep = "-"
 )
 # Use bincraft's codename detection for S3 paths (e.g. "rhel10" not "redhat10")
-codename = bincraft::set_codename(NULL)
+codename <- bincraft::set_codename(NULL)
 
 con <- DBI::dbConnect(
   RPostgres::Postgres(),
@@ -35,8 +35,8 @@ con <- DBI::dbConnect(
   sslmode = "require"
 )
 
-cran_archive = tools::CRAN_archive_db()
-cran_release = tools::CRAN_package_db()
+cran_archive <- tools::CRAN_archive_db()
+cran_release <- tools::CRAN_package_db()
 # Subset cran_archive to only those packages
 cran_archive_in_release <- cran_archive[
   names(cran_archive) %in% cran_release$Package
@@ -84,13 +84,14 @@ s3fs::s3_file_system(
   region_name = "eu-central-003",
   refresh = TRUE
 )
-s3_pkgs = s3fs::s3_dir_ls(
+s3_pkgs <- s3fs::s3_dir_ls(
   sprintf("devxy-rpkgs-binaries/%s/%s/latest/src/contrib", arch, codename),
   recurse = TRUE
 )
 
 # Save the raw S3 file listing for the build step to use as s3_package_cache
-# This avoids loading s3fs/reticulate in the build container, saving memory for pak forks
+# This avoids loading s3fs/reticulate in the build container, saving memory for
+# the dependency-installer subprocesses
 saveRDS(basename(s3_pkgs), "/mnt/cache/packages/s3_cache.rds")
 
 file_names <- basename(s3_pkgs)
diff --git a/local/r-minor-helpers.R b/local/r-minor-helpers.R
index 6f01c29..65aafdf 100644
--- a/local/r-minor-helpers.R
+++ b/local/r-minor-helpers.R
@@ -31,42 +31,3 @@ parse_build_args <- function(args) {
     ncpus = as.integer(pos[3L])
   )
 }
-
-# Bound the {pkgcache} metadata dir, which otherwise grows without limit: the
-# "patched" repo mints a new content hash on every PACKAGES change, so each build
-# writes a fresh ~70 MB _metadata/pkgs-<hash>.rds (+ patched-<hash>/) that is
-# never reused. Keep the `keep` newest entries by mtime; only remove entries
-# older than `min_age_secs`, so a concurrent split-job's in-flight files are
-# never deleted (each build uses a unique hash, so aged entries are
-# unreferenced). Stable repo dirs (CRAN-*, BioC*, INLA-*) and pkg/ downloads are
-# not matched and thus preserved. Returns the number of entries removed.
-trim_pkgcache_metadata <- function(cache_dir = Sys.getenv("R_PKG_CACHE_DIR"),
-                                   keep = 20L,
-                                   min_age_secs = 600) {
-  meta <- file.path(cache_dir, "R", "pkgcache", "_metadata")
-  if (!nzchar(cache_dir) || !dir.exists(meta)) {
-    return(0L)
-  }
-  entries <- c(
-    Sys.glob(file.path(meta, "patched-*")),
-    Sys.glob(file.path(meta, "pkgs-*.rds"))
-  )
-  if (length(entries) == 0L) {
-    return(0L)
-  }
-  info <- file.info(entries)
-  order_new_first <- order(info$mtime, decreasing = TRUE)
-  ranked <- entries[order_new_first]
-  ranked_mtime <- info$mtime[order_new_first]
-  if (length(ranked) <= keep) {
-    return(0L)
-  }
-  candidates <- ranked[(keep + 1L):length(ranked)]
-  candidate_age <- as.numeric(Sys.time()) - as.numeric(ranked_mtime[(keep + 1L):length(ranked)])
-  removable <- candidates[candidate_age >= min_age_secs]
-  if (length(removable) == 0L) {
-    return(0L)
-  }
-  unlink(removable, recursive = TRUE, force = TRUE)
-  length(removable)
-}
diff --git a/local/test-package-loading.R b/local/test-package-loading.R
index 26a2e82..a3b7a28 100644
--- a/local/test-package-loading.R
+++ b/local/test-package-loading.R
@@ -1,22 +1,28 @@
-install.packages(
-  "pak",
-  repos = sprintf(
-    "https://r-lib.github.io/p/pak/stable/%s/%s/%s",
-    .Platform$pkgType,
-    R.Version()$os,
-    R.Version()$arch
+# Installs every CRAN package one by one and checks that it loads. Dependencies
+# go through uvr via local/uvr-install.sh, which bootstraps the uvr binary on
+# first use and installs into .libPaths()[1].
+uvr_install <- function(pkg) {
+  Sys.setenv(
+    UVR_R_BIN = file.path(R.home("bin"), "R"),
+    UVR_TARGET_LIB = .libPaths()[1L]
   )
-)
+  status <- system2("local/uvr-install.sh", shQuote(pkg))
+  if (!identical(status, 0L)) {
+    stop(
+      sprintf("uvr failed to install %s (exit %s)", pkg, status),
+      call. = FALSE
+    )
+  }
+}
 
-Sys.setenv(PKG_SYSREQS = TRUE)
 all_pkgs <- rownames(available.packages())
 
-to_skip = c("ABRSQOL", "ACA", "ACE.CoCo")
-all_pkgs = setdiff(all_pkgs, to_skip)
+to_skip <- c("ABRSQOL", "ACA", "ACE.CoCo")
+all_pkgs <- setdiff(all_pkgs, to_skip)
 
 for (i in all_pkgs) {
   message(sprintf("\nInstalling %s", i))
-  pak::pkg_install(i)
+  uvr_install(i)
   library(i, character.only = TRUE)
 }
 
@@ -323,7 +329,7 @@ if (length(to_process) == 0) {
 } else {
   for (i in to_process) {
     message(sprintf("\nInstalling %s", i))
-    pak::pkg_install(i)
+    uvr_install(i)
     library(i, character.only = TRUE)
   }
   # Update to_skip to include all up to the last processed
diff --git a/local/tests/test-trim-pkgcache.R b/local/tests/test-trim-pkgcache.R
deleted file mode 100644
index 1a5b418..0000000
--- a/local/tests/test-trim-pkgcache.R
+++ /dev/null
@@ -1,68 +0,0 @@
-source(file.path("..", "r-minor-helpers.R"))
-
-# Build a fake _metadata dir under a temp R_PKG_CACHE_DIR. Each entry's mtime is
-# set to `age_secs` in the past so we can exercise the age gate deterministically.
-make_meta <- function(patched = 0L, pkgs = 0L, keep_repos = TRUE, age_secs = 3600) {
-  root <- tempfile("pkgcache-")
-  meta <- file.path(root, "R", "pkgcache", "_metadata")
-  dir.create(meta, recursive = TRUE)
-  old <- Sys.time() - age_secs
-  mk_dir <- function(p) { dir.create(p); Sys.setFileTime(p, old); p }
-  mk_file <- function(p) { writeLines("x", p); Sys.setFileTime(p, old); p }
-  for (i in seq_len(patched)) mk_dir(file.path(meta, sprintf("patched-%03d", i)))
-  for (i in seq_len(pkgs)) mk_file(file.path(meta, sprintf("pkgs-%03d.rds", i)))
-  if (keep_repos) {
-    mk_dir(file.path(meta, "CRAN-075c426938"))
-    mk_dir(file.path(meta, "BioCsoft-1ac964ed6c"))
-    mk_file(file.path(meta, "bioc-sysreqs.dcf.gz"))
-    mk_dir(file.path(root, "R", "pkgcache", "pkg")) # downloads, must survive
-  }
-  root
-}
-
-n_churn <- function(root) {
-  meta <- file.path(root, "R", "pkgcache", "_metadata")
-  length(Sys.glob(file.path(meta, "patched-*"))) +
-    length(Sys.glob(file.path(meta, "pkgs-*.rds")))
-}
-
-test_that("empty cache_dir is a no-op", {
-  expect_identical(trim_pkgcache_metadata("", keep = 5L, min_age_secs = 0), 0L)
-})
-
-test_that("missing _metadata dir is a no-op", {
-  expect_identical(
-    trim_pkgcache_metadata(tempfile("absent-"), keep = 5L, min_age_secs = 0),
-    0L
-  )
-})
-
-test_that("fewer than keep entries removes nothing", {
-  root <- make_meta(patched = 2L, pkgs = 2L)
-  expect_identical(trim_pkgcache_metadata(root, keep = 20L, min_age_secs = 0), 0L)
-  expect_identical(n_churn(root), 4L)
-})
-
-test_that("trims down to keep newest, leaving churn == keep", {
-  root <- make_meta(patched = 30L, pkgs = 30L) # 60 churn entries, all old
-  removed <- trim_pkgcache_metadata(root, keep = 20L, min_age_secs = 0)
-  expect_identical(removed, 40L)
-  expect_identical(n_churn(root), 20L)
-})
-
-test_that("entries younger than min_age_secs are protected", {
-  root <- make_meta(patched = 30L, pkgs = 0L, keep_repos = FALSE, age_secs = 60)
-  # keep=5 would drop 25, but all are 60s old < 600s gate -> nothing removed
-  expect_identical(trim_pkgcache_metadata(root, keep = 5L, min_age_secs = 600), 0L)
-  expect_identical(n_churn(root), 30L)
-})
-
-test_that("stable repo dirs and pkg downloads are never touched", {
-  root <- make_meta(patched = 30L, pkgs = 30L)
-  trim_pkgcache_metadata(root, keep = 0L, min_age_secs = 0)
-  meta <- file.path(root, "R", "pkgcache", "_metadata")
-  expect_true(dir.exists(file.path(meta, "CRAN-075c426938")))
-  expect_true(dir.exists(file.path(meta, "BioCsoft-1ac964ed6c")))
-  expect_true(file.exists(file.path(meta, "bioc-sysreqs.dcf.gz")))
-  expect_true(dir.exists(file.path(root, "R", "pkgcache", "pkg")))
-})
diff --git a/local/uvr-install.sh b/local/uvr-install.sh
new file mode 100755
index 0000000..e1c4d0f
--- /dev/null
+++ b/local/uvr-install.sh
@@ -0,0 +1,90 @@
+#!/bin/sh
+# Install R packages into the CI library with uvr (https://github.com/nbafrank/uvr).
+#
+# Usage:
+#   local/uvr-install.sh httr2 jsonlite
+#   local/uvr-install.sh forgejo::codefloe.com/rpkgs/bincraft@v4.4.3
+#
+# Replaces `pak::pak(...)`. uvr is project-scoped: `uvr add` refuses to run
+# outside a project and always writes to `.uvr/library/`, and only
+# `uvr sync --library` can target an existing library. The project is therefore
+# minted in a scratch directory under TMPDIR and thrown away afterwards; that
+# also keeps `uvr init`'s `.Rprofile` out of the repo checkout, where it would
+# hijack `.libPaths()` for every other R call in the pipeline.
+#
+# Pruning is a no-op here: uvr disables it whenever `--library` is passed,
+# precisely because such a target may be shared (`/mnt/cache/R-pkgs` holds
+# bincraft and its dependencies alongside whatever this script installs).
+#
+# System dependencies come from uvr's vendored r-system-requirements rules, so
+# `pak::sysreqs_db_update()` and `PKG_SYSREQS_PLATFORM` are no longer needed.
+#
+# Environment:
+#   UVR_R_BIN        R interpreter to install for; set by install-bincraft.R so
+#                    the per-R-minor passes target their own R, not the primary
+#   R_VERSION        fallback interpreter selector (/opt/R/<version>/bin/R)
+#   UVR_TARGET_LIB   target library; defaults to R_LIBS_USER, then to the
+#                    active R's .libPaths()[1] (which is where pak wrote)
+#   UVR_INSTALL_DIR  where the uvr binary lands (default /usr/local/bin)
+
+set -eu
+
+# renovate: datasource=github-releases depName=nbafrank/uvr
+UVR_PIN="v0.4.4"
+
+if [ "$#" -eq 0 ]; then
+  echo "usage: $0 <pkg-spec>..." >&2
+  exit 2
+fi
+
+# The build images keep R under /opt/R/<version> and off PATH. uvr resolves the
+# interpreter via PATH and never downloads one unless `uvr r install` is run, so
+# put the requested R first.
+r_bin="${UVR_R_BIN:-}"
+if [ -z "$r_bin" ] && [ -n "${R_VERSION:-}" ] && [ -x "/opt/R/${R_VERSION}/bin/R" ]; then
+  r_bin="/opt/R/${R_VERSION}/bin/R"
+fi
+if [ -n "$r_bin" ]; then
+  PATH="$(dirname "$r_bin"):$PATH"
+  export PATH
+else
+  r_bin="$(command -v R)"
+fi
+
+target_lib="${UVR_TARGET_LIB:-${R_LIBS_USER:-}}"
+if [ -z "$target_lib" ]; then
+  target_lib="$("$r_bin" --no-echo --no-save -e 'cat(.libPaths()[1])')"
+fi
+if [ -z "$target_lib" ]; then
+  echo "error: could not determine a target library; set UVR_TARGET_LIB" >&2
+  exit 2
+fi
+mkdir -p "$target_lib"
+
+# Pin the manifest to the active R so the lockfile's R stays in step with the
+# library's R sentinel. Without that, uvr can decide the library is ABI-stale
+# and wipe it -- and this target is shared with bincraft. uvr only discovers R
+# via PATH/R_HOME (it does not scan /opt/R), so the R put on PATH above is the
+# only candidate this constraint can resolve to.
+# shellcheck disable=SC2016  # $major/$minor are R expressions, not shell vars
+r_full="$("$r_bin" --no-echo --no-save -e 'cat(paste(R.version$major, R.version$minor, sep = "."))')"
+
+install_dir="${UVR_INSTALL_DIR:-/usr/local/bin}"
+uvr_bin="${install_dir}/uvr"
+if [ ! -x "$uvr_bin" ]; then
+  echo "Bootstrapping uvr ${UVR_PIN} into ${install_dir}"
+  UVR_INSTALL_DIR="$install_dir" UVR_VERSION="$UVR_PIN" \
+    sh -c 'curl -fsSL https://raw.githubusercontent.com/nbafrank/uvr/main/install.sh | sh'
+fi
+
+project_dir="${TMPDIR:-/tmp}/uvr-ci-$$"
+rm -rf "$project_dir"
+mkdir -p "$project_dir"
+trap 'rm -rf "$project_dir"' EXIT
+cd "$project_dir"
+
+"$uvr_bin" init --here --r-version "$r_full"
+# --no-install: resolve and lock only. The install happens in the sync below,
+# which is the only command that honours --library.
+"$uvr_bin" add --no-install "$@"
+"$uvr_bin" sync --library "$target_lib" --install-system-deps
diff --git a/renovate.json b/renovate.json
index 8c8e208..7b2c3b3 100644
--- a/renovate.json
+++ b/renovate.json
@@ -1,7 +1,12 @@
 {
   "$schema": "https://docs.renovatebot.com/renovate-schema.json",
   "extends": ["local>devxy/renovate-config"],
-  "ignorePaths": ["docker/**", ".crow/process-updates.yaml", ".crow/build-all-versions.yaml", ".crow/weekly-rebuild-missing.yaml"],
+  "ignorePaths": [
+    "docker/**",
+    ".crow/process-updates.yaml",
+    ".crow/build-all-versions.yaml",
+    ".crow/weekly-rebuild-missing.yaml"
+  ],
   "customManagers": [
     {
       "customType": "regex",
@@ -14,6 +19,13 @@
       "packageNameTemplate": "https://codefloe.com/rpkgs/bincraft.git",
       "datasourceTemplate": "git-tags",
       "extractVersionTemplate": "^v?(?<version>.+)$"
+    },
+    {
+      "customType": "regex",
+      "fileMatch": ["^local/uvr-install\\.sh$"],
+      "matchStrings": [
+        "# renovate: datasource=(?<datasource>\\S+) depName=(?<depName>\\S+)\\s+UVR_PIN=\"(?<currentValue>[^\"]+)\""
+      ]
     }
   ]
 }