From f8fb5b7173074a8fc6599e7be6f55fc7cecdcfea Mon Sep 17 00:00:00 2001
From: Ashley Baldry <arbaldry91@gmail.com>
Date: Fri, 21 Aug 2026 17:04:15 +0100
Subject: [PATCH 01/10] Add module that generates lockfile

---
 DESCRIPTION                           |  1 +
 R/lockfile_module.R                   | 82 +++++++++++++++++++++++++++
 man/lockfile_module.Rd                | 72 +++++++++++++++++++++++
 tests/testthat/test-lockfile_module.R | 21 +++++++
 4 files changed, 176 insertions(+)
 create mode 100644 R/lockfile_module.R
 create mode 100644 man/lockfile_module.Rd
 create mode 100644 tests/testthat/test-lockfile_module.R

diff --git a/DESCRIPTION b/DESCRIPTION
index aeee72b..d22cd25 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -49,5 +49,6 @@ Collate:
     'chunk_call.R'
     'chunk_generic.R'
     'chunk_reactive.R'
+    'lockfile_module.R'
     'package.R'
     'reprex_reactive.R'
diff --git a/R/lockfile_module.R b/R/lockfile_module.R
new file mode 100644
index 0000000..b03374f
--- /dev/null
+++ b/R/lockfile_module.R
@@ -0,0 +1,82 @@
+#' Lockfile Download Module
+#'
+#' @description
+#' A Shiny module offering a single download control that writes an `renv`
+#' lockfile reproducing one or more reactives (see [reprex_lockfile()]).
+#'
+#' `lockfileUI()` returns a plain [shiny::downloadButton()], so it can be
+#' dropped wherever a control fits - inside a `bslib::nav_menu()`, a sidebar, or
+#' a toolbar - without pulling in any layout of its own.
+#'
+#' To build a bespoke interface instead, skip the module and call
+#' [reprex_packages()] to populate your own package picker, feeding the choice
+#' back through the `packages` argument of [reprex_lockfile()].
+#'
+#' @param id Module id, shared between `lockfileUI()` and `lockfileServer()`.
+#' @param label Button label.
+#' @param ... One or more `shiny::reactive` objects to reproduce.
+#' @param packages Packages to snapshot, passed to [reprex_lockfile()]. May be a
+#' reactive (for example one fed by a user's own package picker), in which case
+#' it is resolved when the download is requested. `NULL` snapshots every
+#' detected package.
+#' @param filename Name of the downloaded lockfile.
+#'
+#' @returns
+#' `lockfileUI()` returns a Shiny UI tag. `lockfileServer()` is called for its
+#' side effect and returns the module's return value invisibly.
+#'
+#' @examplesIf interactive() && rlang::is_installed(c("shiny", "renv", "bslib"))
+#' library(shiny)
+#'
+#' ui <- bslib::page_navbar(
+#'   title = "Demo",
+#'   bslib::nav_panel(
+#'     "Table",
+#'     sliderInput("w", "Minimum petal width", 0, 2.5, 0.5, step = 0.1),
+#'     tableOutput("table")
+#'   ),
+#'   bslib::nav_spacer(),
+#'   bslib::nav_item(lockfileUI("lock", "Download renv.lock"))
+#' )
+#'
+#' server <- function(input, output, session) {
+#'   filtered <- reactive(purrr::keep(iris, is.numeric)[iris$Petal.Width > input$w, ])
+#'
+#'   output$table <- renderTable(head(filtered()))
+#'   lockfileServer("lock", filtered)
+#' }
+#'
+#' shinyApp(ui, server)
+#'
+#' @seealso
+#' A fuller worked example, covering both this module and a custom package
+#' picker, ships with the package:
+#' `shiny::runApp(system.file("examples-shiny/lockfile", package = "shinyreprex"))`
+#'
+#' @name lockfile_module
+NULL
+
+#' @rdname lockfile_module
+#' @export
+lockfileUI <- function(id, label = "Download lockfile") {
+  shiny::downloadButton(shiny::NS(id, "download"), label)
+}
+
+#' @rdname lockfile_module
+#' @export
+lockfileServer <- function(id, ..., packages = NULL, filename = "renv.lock") {
+  reactives <- list(...)
+
+  shiny::moduleServer(id, function(input, output, session) {
+    output$download <- shiny::downloadHandler(
+      filename = function() filename,
+      content = function(file) {
+        pkgs <- if (shiny::is.reactive(packages)) packages() else packages
+        do.call(
+          reprex_lockfile,
+          c(reactives, list(packages = pkgs, lockfile = file))
+        )
+      }
+    )
+  })
+}
diff --git a/man/lockfile_module.Rd b/man/lockfile_module.Rd
new file mode 100644
index 0000000..d4e8528
--- /dev/null
+++ b/man/lockfile_module.Rd
@@ -0,0 +1,72 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/lockfile_module.R
+\name{lockfile_module}
+\alias{lockfile_module}
+\alias{lockfileUI}
+\alias{lockfileServer}
+\title{Lockfile Download Module}
+\usage{
+lockfileUI(id, label = "Download lockfile")
+
+lockfileServer(id, ..., packages = NULL, filename = "renv.lock")
+}
+\arguments{
+\item{id}{Module id, shared between \code{lockfileUI()} and \code{lockfileServer()}.}
+
+\item{label}{Button label.}
+
+\item{...}{One or more \code{shiny::reactive} objects to reproduce.}
+
+\item{packages}{Packages to snapshot, passed to \code{\link[=reprex_lockfile]{reprex_lockfile()}}. May be a
+reactive (for example one fed by a user's own package picker), in which case
+it is resolved when the download is requested. \code{NULL} snapshots every
+detected package.}
+
+\item{filename}{Name of the downloaded lockfile.}
+}
+\value{
+\code{lockfileUI()} returns a Shiny UI tag. \code{lockfileServer()} is called for its
+side effect and returns the module's return value invisibly.
+}
+\description{
+A Shiny module offering a single download control that writes an \code{renv}
+lockfile reproducing one or more reactives (see \code{\link[=reprex_lockfile]{reprex_lockfile()}}).
+
+\code{lockfileUI()} returns a plain \code{\link[shiny:downloadButton]{shiny::downloadButton()}}, so it can be
+dropped wherever a control fits - inside a \code{bslib::nav_menu()}, a sidebar, or
+a toolbar - without pulling in any layout of its own.
+
+To build a bespoke interface instead, skip the module and call
+\code{\link[=reprex_packages]{reprex_packages()}} to populate your own package picker, feeding the choice
+back through the \code{packages} argument of \code{\link[=reprex_lockfile]{reprex_lockfile()}}.
+}
+\examples{
+\dontshow{if (interactive() && rlang::is_installed(c("shiny", "renv", "bslib"))) withAutoprint(\{ # examplesIf}
+library(shiny)
+
+ui <- bslib::page_navbar(
+  title = "Demo",
+  bslib::nav_panel(
+    "Table",
+    sliderInput("w", "Minimum petal width", 0, 2.5, 0.5, step = 0.1),
+    tableOutput("table")
+  ),
+  bslib::nav_spacer(),
+  bslib::nav_item(lockfileUI("lock", "Download renv.lock"))
+)
+
+server <- function(input, output, session) {
+  filtered <- reactive(purrr::keep(iris, is.numeric)[iris$Petal.Width > input$w, ])
+
+  output$table <- renderTable(head(filtered()))
+  lockfileServer("lock", filtered)
+}
+
+shinyApp(ui, server)
+\dontshow{\}) # examplesIf}
+}
+\seealso{
+A fuller worked example, covering both this module and a custom package
+picker, ships with the package:
+\code{shiny::runApp(system.file("examples-shiny/lockfile", package = "shinyreprex"))}
+}
diff --git a/tests/testthat/test-lockfile_module.R b/tests/testthat/test-lockfile_module.R
new file mode 100644
index 0000000..20a8f1e
--- /dev/null
+++ b/tests/testthat/test-lockfile_module.R
@@ -0,0 +1,21 @@
+test_that("lockfileUI returns a download control namespaced to the module id", {
+  ui <- lockfileUI("lock", "Grab it")
+  expect_s3_class(ui, "shiny.tag")
+  expect_match(as.character(ui), "lock-download", fixed = TRUE)
+  expect_match(as.character(ui), "Grab it", fixed = TRUE)
+})
+
+test_that("lockfileServer wires into an app without error", {
+  server <- function(input, output, session) {
+    r <- reactive(iris[iris$Petal.Width > input$w, ])
+    lockfileServer("lock", r)
+  }
+
+  # Constructing the module inside testServer runs its setup; a broken wiring
+  # would throw here. The download content itself is exercised via
+  # reprex_lockfile()'s own tests rather than a live renv snapshot.
+  shiny::testServer(server, {
+    session$setInputs(w = 1)
+    succeed()
+  })
+})

From 69c84ca110d87911ce8c215a23be28317cf5162b Mon Sep 17 00:00:00 2001
From: Ashley Baldry <arbaldry91@gmail.com>
Date: Fri, 21 Aug 2026 17:05:45 +0100
Subject: [PATCH 02/10] Adding example app

---
 inst/examples-shiny/lockfile/app.R   | 105 +++++++++++++++++++++++++++
 tests/testthat/test-examples-shiny.R |  50 +++++++++++++
 2 files changed, 155 insertions(+)
 create mode 100644 inst/examples-shiny/lockfile/app.R
 create mode 100644 tests/testthat/test-examples-shiny.R

diff --git a/inst/examples-shiny/lockfile/app.R b/inst/examples-shiny/lockfile/app.R
new file mode 100644
index 0000000..e2716f2
--- /dev/null
+++ b/inst/examples-shiny/lockfile/app.R
@@ -0,0 +1,105 @@
+library(shiny)
+library(shinyreprex)
+
+# Demonstrates the two ways to offer a lockfile alongside a reprex:
+#   1. `lockfileUI`/`lockfileServer` - a single control, dropped in the navbar.
+#   2. `reprex_packages` - feeding a custom picker, wired up by hand.
+
+ui <- bslib::page_navbar(
+  title = "shinyreprex",
+
+  bslib::nav_panel(
+    "Reproduce",
+    bslib::layout_sidebar(
+      sidebar = bslib::sidebar(
+        sliderInput(
+          "min_width",
+          "Minimum petal width",
+          min(iris$Petal.Width),
+          max(iris$Petal.Width),
+          min(iris$Petal.Width),
+          step = 0.1
+        ),
+        selectInput(
+          "summary_fn",
+          "Summary function",
+          c(Mean = "mean", Median = "median", `Std. dev` = "sd")
+        ),
+        checkboxGroupInput(
+          "columns",
+          "Columns to summarise",
+          c("Sepal.Length", "Sepal.Width", "Petal.Length"),
+          selected = "Sepal.Width"
+        ),
+        actionButton("update", "Update", class = "btn-primary")
+      ),
+      bslib::layout_columns(
+        bslib::card(bslib::card_header("Output"), tableOutput("table")),
+        bslib::card(bslib::card_header("Reproducible script"), verbatimTextOutput("code"))
+      )
+    )
+  ),
+
+  bslib::nav_panel(
+    "Environment",
+    bslib::card(
+      bslib::card_header("Choose what to pin"),
+      p(
+        "The packages below were detected in the reactive by ", code("reprex_packages()"),
+        ". Narrow the selection, or add a package the detector could not see, then ",
+        "download a lockfile scoped to that choice."
+      ),
+      uiOutput("package_picker"),
+      downloadButton("custom_lock", "Download selected", class = "btn-secondary")
+    )
+  ),
+
+  bslib::nav_spacer(),
+  bslib::nav_item(lockfileUI("lock", "Download renv.lock"))
+)
+
+server <- function(input, output, session) {
+  iris_filt <- reactive({
+    iris[iris$Petal.Width >= input$min_width, ]
+  }) |>
+    bindEvent(input$update, ignoreNULL = FALSE)
+
+  summary_tbl <- reactive({
+    purrr::map(
+      input$columns,
+      dat = iris_filt(),
+      fn = input$summary_fn,
+      \(col, dat, fn) {
+        aggregate(as.formula(paste(col, "~ Species")), data = dat, FUN = get(fn))
+      }
+    ) |>
+      purrr::reduce(merge, by = "Species")
+  }) |>
+    bindEvent(input$update, ignoreNULL = FALSE)
+
+  output$table <- renderTable(summary_tbl())
+
+  # Bound to the reactive so the script only refreshes when the output does.
+  output$code <- renderText(reprex_reactive(summary_tbl)) |>
+    bindEvent(summary_tbl())
+
+  # 1. The drop-in: one control in the navbar, pinning everything detected.
+  lockfileServer("lock", summary_tbl)
+
+  # 2. The custom path: same engine, user-selected packages.
+  detected <- reactive(reprex_packages(summary_tbl)) |>
+    bindEvent(summary_tbl())
+
+  output$package_picker <- renderUI({
+    checkboxGroupInput("packages", NULL, choices = detected(), selected = detected())
+  })
+
+  output$custom_lock <- downloadHandler(
+    filename = function() "renv.lock",
+    content = function(file) {
+      reprex_lockfile(summary_tbl, packages = input$packages, lockfile = file)
+    }
+  )
+}
+
+shinyApp(ui, server)
diff --git a/tests/testthat/test-examples-shiny.R b/tests/testthat/test-examples-shiny.R
new file mode 100644
index 0000000..ca9a61e
--- /dev/null
+++ b/tests/testthat/test-examples-shiny.R
@@ -0,0 +1,50 @@
+app_dir <- function(name) {
+  path <- system.file("examples-shiny", name, package = "shinyreprex")
+  if (!nzchar(path)) skip(paste0("Example app '", name, "' is not installed"))
+  path
+}
+
+test_that("The lockfile example app generates a script that reproduces its own output", {
+  skip_if_not_installed("shiny")
+
+  shiny::testServer(app_dir("lockfile"), {
+    session$setInputs(
+      min_width  = 0.5,
+      summary_fn = "median",
+      columns    = c("Sepal.Width", "Petal.Length"),
+      update     = 1
+    )
+
+    expect_identical(reprex_packages(summary_tbl), "purrr")
+    expect_identical(
+      eval(parse(text = output$code), envir = new.env()),
+      summary_tbl()
+    )
+  })
+})
+
+test_that("The lockfile example app offers a restorable lockfile from both the module and the custom picker", {
+  skip_on_cran()
+  skip_if_not_installed("shiny")
+  skip_if_not_installed("renv")
+
+  shiny::testServer(app_dir("lockfile"), {
+    session$setInputs(
+      min_width  = 0.5,
+      summary_fn = "median",
+      columns    = "Sepal.Width",
+      update     = 1,
+      packages   = "purrr"
+    )
+
+    # Reading a download output runs its content function and returns the path.
+    for (lock in c(output$`lock-download`, output$custom_lock)) {
+      parsed <- renv::lockfile_read(lock)
+      expect_identical(parsed$R$Version, as.character(getRversion()))
+      expect_identical(
+        parsed$Packages$purrr$Version,
+        as.character(utils::packageVersion("purrr"))
+      )
+    }
+  })
+})

From 57f96e06c74d44792393a7d3e61fe2b6280d5c9e Mon Sep 17 00:00:00 2001
From: Ashley Baldry <arbaldry91@gmail.com>
Date: Fri, 28 Aug 2026 16:50:10 +0100
Subject: [PATCH 03/10] Remove unused lockfile module

---
 R/lockfile_module.R                   | 82 ---------------------------
 man/lockfile_module.Rd                | 72 -----------------------
 tests/testthat/test-lockfile_module.R | 21 -------
 3 files changed, 175 deletions(-)
 delete mode 100644 R/lockfile_module.R
 delete mode 100644 man/lockfile_module.Rd
 delete mode 100644 tests/testthat/test-lockfile_module.R

diff --git a/R/lockfile_module.R b/R/lockfile_module.R
deleted file mode 100644
index b03374f..0000000
--- a/R/lockfile_module.R
+++ /dev/null
@@ -1,82 +0,0 @@
-#' Lockfile Download Module
-#'
-#' @description
-#' A Shiny module offering a single download control that writes an `renv`
-#' lockfile reproducing one or more reactives (see [reprex_lockfile()]).
-#'
-#' `lockfileUI()` returns a plain [shiny::downloadButton()], so it can be
-#' dropped wherever a control fits - inside a `bslib::nav_menu()`, a sidebar, or
-#' a toolbar - without pulling in any layout of its own.
-#'
-#' To build a bespoke interface instead, skip the module and call
-#' [reprex_packages()] to populate your own package picker, feeding the choice
-#' back through the `packages` argument of [reprex_lockfile()].
-#'
-#' @param id Module id, shared between `lockfileUI()` and `lockfileServer()`.
-#' @param label Button label.
-#' @param ... One or more `shiny::reactive` objects to reproduce.
-#' @param packages Packages to snapshot, passed to [reprex_lockfile()]. May be a
-#' reactive (for example one fed by a user's own package picker), in which case
-#' it is resolved when the download is requested. `NULL` snapshots every
-#' detected package.
-#' @param filename Name of the downloaded lockfile.
-#'
-#' @returns
-#' `lockfileUI()` returns a Shiny UI tag. `lockfileServer()` is called for its
-#' side effect and returns the module's return value invisibly.
-#'
-#' @examplesIf interactive() && rlang::is_installed(c("shiny", "renv", "bslib"))
-#' library(shiny)
-#'
-#' ui <- bslib::page_navbar(
-#'   title = "Demo",
-#'   bslib::nav_panel(
-#'     "Table",
-#'     sliderInput("w", "Minimum petal width", 0, 2.5, 0.5, step = 0.1),
-#'     tableOutput("table")
-#'   ),
-#'   bslib::nav_spacer(),
-#'   bslib::nav_item(lockfileUI("lock", "Download renv.lock"))
-#' )
-#'
-#' server <- function(input, output, session) {
-#'   filtered <- reactive(purrr::keep(iris, is.numeric)[iris$Petal.Width > input$w, ])
-#'
-#'   output$table <- renderTable(head(filtered()))
-#'   lockfileServer("lock", filtered)
-#' }
-#'
-#' shinyApp(ui, server)
-#'
-#' @seealso
-#' A fuller worked example, covering both this module and a custom package
-#' picker, ships with the package:
-#' `shiny::runApp(system.file("examples-shiny/lockfile", package = "shinyreprex"))`
-#'
-#' @name lockfile_module
-NULL
-
-#' @rdname lockfile_module
-#' @export
-lockfileUI <- function(id, label = "Download lockfile") {
-  shiny::downloadButton(shiny::NS(id, "download"), label)
-}
-
-#' @rdname lockfile_module
-#' @export
-lockfileServer <- function(id, ..., packages = NULL, filename = "renv.lock") {
-  reactives <- list(...)
-
-  shiny::moduleServer(id, function(input, output, session) {
-    output$download <- shiny::downloadHandler(
-      filename = function() filename,
-      content = function(file) {
-        pkgs <- if (shiny::is.reactive(packages)) packages() else packages
-        do.call(
-          reprex_lockfile,
-          c(reactives, list(packages = pkgs, lockfile = file))
-        )
-      }
-    )
-  })
-}
diff --git a/man/lockfile_module.Rd b/man/lockfile_module.Rd
deleted file mode 100644
index d4e8528..0000000
--- a/man/lockfile_module.Rd
+++ /dev/null
@@ -1,72 +0,0 @@
-% Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/lockfile_module.R
-\name{lockfile_module}
-\alias{lockfile_module}
-\alias{lockfileUI}
-\alias{lockfileServer}
-\title{Lockfile Download Module}
-\usage{
-lockfileUI(id, label = "Download lockfile")
-
-lockfileServer(id, ..., packages = NULL, filename = "renv.lock")
-}
-\arguments{
-\item{id}{Module id, shared between \code{lockfileUI()} and \code{lockfileServer()}.}
-
-\item{label}{Button label.}
-
-\item{...}{One or more \code{shiny::reactive} objects to reproduce.}
-
-\item{packages}{Packages to snapshot, passed to \code{\link[=reprex_lockfile]{reprex_lockfile()}}. May be a
-reactive (for example one fed by a user's own package picker), in which case
-it is resolved when the download is requested. \code{NULL} snapshots every
-detected package.}
-
-\item{filename}{Name of the downloaded lockfile.}
-}
-\value{
-\code{lockfileUI()} returns a Shiny UI tag. \code{lockfileServer()} is called for its
-side effect and returns the module's return value invisibly.
-}
-\description{
-A Shiny module offering a single download control that writes an \code{renv}
-lockfile reproducing one or more reactives (see \code{\link[=reprex_lockfile]{reprex_lockfile()}}).
-
-\code{lockfileUI()} returns a plain \code{\link[shiny:downloadButton]{shiny::downloadButton()}}, so it can be
-dropped wherever a control fits - inside a \code{bslib::nav_menu()}, a sidebar, or
-a toolbar - without pulling in any layout of its own.
-
-To build a bespoke interface instead, skip the module and call
-\code{\link[=reprex_packages]{reprex_packages()}} to populate your own package picker, feeding the choice
-back through the \code{packages} argument of \code{\link[=reprex_lockfile]{reprex_lockfile()}}.
-}
-\examples{
-\dontshow{if (interactive() && rlang::is_installed(c("shiny", "renv", "bslib"))) withAutoprint(\{ # examplesIf}
-library(shiny)
-
-ui <- bslib::page_navbar(
-  title = "Demo",
-  bslib::nav_panel(
-    "Table",
-    sliderInput("w", "Minimum petal width", 0, 2.5, 0.5, step = 0.1),
-    tableOutput("table")
-  ),
-  bslib::nav_spacer(),
-  bslib::nav_item(lockfileUI("lock", "Download renv.lock"))
-)
-
-server <- function(input, output, session) {
-  filtered <- reactive(purrr::keep(iris, is.numeric)[iris$Petal.Width > input$w, ])
-
-  output$table <- renderTable(head(filtered()))
-  lockfileServer("lock", filtered)
-}
-
-shinyApp(ui, server)
-\dontshow{\}) # examplesIf}
-}
-\seealso{
-A fuller worked example, covering both this module and a custom package
-picker, ships with the package:
-\code{shiny::runApp(system.file("examples-shiny/lockfile", package = "shinyreprex"))}
-}
diff --git a/tests/testthat/test-lockfile_module.R b/tests/testthat/test-lockfile_module.R
deleted file mode 100644
index 20a8f1e..0000000
--- a/tests/testthat/test-lockfile_module.R
+++ /dev/null
@@ -1,21 +0,0 @@
-test_that("lockfileUI returns a download control namespaced to the module id", {
-  ui <- lockfileUI("lock", "Grab it")
-  expect_s3_class(ui, "shiny.tag")
-  expect_match(as.character(ui), "lock-download", fixed = TRUE)
-  expect_match(as.character(ui), "Grab it", fixed = TRUE)
-})
-
-test_that("lockfileServer wires into an app without error", {
-  server <- function(input, output, session) {
-    r <- reactive(iris[iris$Petal.Width > input$w, ])
-    lockfileServer("lock", r)
-  }
-
-  # Constructing the module inside testServer runs its setup; a broken wiring
-  # would throw here. The download content itself is exercised via
-  # reprex_lockfile()'s own tests rather than a live renv snapshot.
-  shiny::testServer(server, {
-    session$setInputs(w = 1)
-    succeed()
-  })
-})

From 1074699f11cc721438c0bab281457fefa78959fb Mon Sep 17 00:00:00 2001
From: Ashley Baldry <arbaldry91@gmail.com>
Date: Fri, 28 Aug 2026 16:52:51 +0100
Subject: [PATCH 04/10] (fix): Ensure missing arguments can be walked when
 evaluating package dependencies

---
 DESCRIPTION                         |  1 -
 R/walk_packages.R                   |  8 +++++---
 tests/testthat/test-walk_packages.R | 11 +++++++++++
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/DESCRIPTION b/DESCRIPTION
index f8b721b..b6ee3db 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -51,7 +51,6 @@ Collate:
     'chunk_call.R'
     'chunk_generic.R'
     'chunk_reactive.R'
-    'lockfile_module.R'
     'package.R'
     'reactive_expression.R'
     'register_reactives.R'
diff --git a/R/walk_packages.R b/R/walk_packages.R
index 64a6785..796a41b 100644
--- a/R/walk_packages.R
+++ b/R/walk_packages.R
@@ -43,8 +43,7 @@ walk_packages <- function(expr, env, seen = character(), packages = character())
 
   call_name <- rlang::call_name(expr)
 
-  # Shiny calls that are stripped when reproducing code contribute nothing, as
-  # the script is intended to run outside of Shiny. Mirrors `class_call_shiny`.
+  # Shiny calls that are stripped when reproducing code contribute nothing
   if (!is.null(call_name) && call_name %in% IGNORED_SHINY_CALLS) {
     return(packages)
   }
@@ -64,7 +63,10 @@ walk_packages <- function(expr, env, seen = character(), packages = character())
 
   packages <- union(packages, get_pkg_name(expr))
 
-  for (arg in as.list(expr)[-1L]) {
+  # Omitted arguments, such as the empty index in `iris[cond, ]` cannot be walked
+  arguments <- purrr::discard(as.list(expr)[-1L], rlang::is_missing)
+
+  for (arg in arguments) {
     packages <- walk_packages(arg, env, seen, packages)
   }
 
diff --git a/tests/testthat/test-walk_packages.R b/tests/testthat/test-walk_packages.R
index 1595118..182f4c0 100644
--- a/tests/testthat/test-walk_packages.R
+++ b/tests/testthat/test-walk_packages.R
@@ -88,6 +88,17 @@ test_that("Shiny calls stripped when reproducing code do not pull in shiny", {
   })
 })
 
+test_that("An omitted index, as in a row subset, does not stop the walk", {
+  test_server <- function(input, output, session) {
+    tbl <- reactive(purrr::keep(iris[iris$Petal.Width > input$w, ], is.numeric))
+  }
+
+  shiny::testServer(test_server, {
+    session$setInputs(w = 1)
+    expect_identical(reprex_packages(tbl), "purrr")
+  })
+})
+
 test_that("A reactive using only base functions reports no packages", {
   test_server <- function(input, output, session) {
     tbl <- reactive(nrow(iris))

From 476aeaf040d56be1de8f6d4604fe39244bf55419 Mon Sep 17 00:00:00 2001
From: Ashley Baldry <arbaldry91@gmail.com>
Date: Mon, 31 Aug 2026 12:51:30 +0100
Subject: [PATCH 05/10] (app): Update to have lock file in options dropdown

---
 DESCRIPTION                          |   1 +
 inst/examples-shiny/lockfile/app.R   | 217 ++++++++++++++++-----------
 tests/testthat/test-examples-shiny.R |  69 ++++++---
 3 files changed, 178 insertions(+), 109 deletions(-)

diff --git a/DESCRIPTION b/DESCRIPTION
index b6ee3db..e597929 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -21,6 +21,7 @@ Imports:
     renv,
     styler
 Suggests:
+    dplyr,
     knitr,
     rmarkdown,
     shiny,
diff --git a/inst/examples-shiny/lockfile/app.R b/inst/examples-shiny/lockfile/app.R
index e2716f2..392df61 100644
--- a/inst/examples-shiny/lockfile/app.R
+++ b/inst/examples-shiny/lockfile/app.R
@@ -1,103 +1,152 @@
 library(shiny)
 library(shinyreprex)
 
-# Demonstrates the two ways to offer a lockfile alongside a reprex:
-#   1. `lockfileUI`/`lockfileServer` - a single control, dropped in the navbar.
-#   2. `reprex_packages` - feeding a custom picker, wired up by hand.
+# Two modules doing different work with different packages. Each registers the
+# reactive behind its own table, so their scripts carry different `library()`
+# calls while the single download in the navbar pins the union of both.
 
+result_cards <- function(ns) {
+  bslib::layout_columns(
+    bslib::card(bslib::card_header("Output"), tableOutput(ns("table"))),
+    bslib::card(bslib::card_header("Reproducible script"), verbatimTextOutput(ns("code")))
+  )
+}
+
+width_slider <- function(ns) {
+  sliderInput(
+    ns("min_width"),
+    "Minimum petal width",
+    min(iris$Petal.Width),
+    max(iris$Petal.Width),
+    min(iris$Petal.Width),
+    step = 0.1
+  )
+}
+
+#### Summarise with {purrr} ####
+summaryUI <- function(id) {
+  ns <- NS(id)
+
+  bslib::layout_sidebar(
+    sidebar = bslib::sidebar(
+      width_slider(ns),
+      selectInput(
+        ns("summary_fn"),
+        "Summary function",
+        c(Mean = "mean", Median = "median", `Std. dev` = "sd")
+      ),
+      actionButton(ns("update"), "Update", class = "btn-primary")
+    ),
+    result_cards(ns)
+  )
+}
+
+summaryServer <- function(id, columns) {
+  moduleServer(id, function(input, output, session) {
+    filtered <- reactive({
+      iris[iris$Petal.Width >= input$min_width, ]
+    }) |>
+      bindEvent(input$update, ignoreNULL = FALSE)
+
+    summary_tbl <- reactive({
+      purrr::map(
+        columns,
+        dat = filtered(),
+        fn = input$summary_fn,
+        \(col, dat, fn) {
+          aggregate(as.formula(paste(col, "~ Species")), data = dat, FUN = get(fn))
+        }
+      ) |>
+        purrr::reduce(merge, by = "Species")
+    }) |>
+      bindEvent(input$update, ignoreNULL = FALSE)
+
+    register_reactives(summary_tbl)
+
+    output$table <- renderTable(summary_tbl())
+    output$code <- renderText(reprex_reactive(summary_tbl)) |>
+      bindEvent(summary_tbl())
+
+    summary_tbl
+  })
+}
+
+#### Count with {dplyr} ####
+countsUI <- function(id) {
+  ns <- NS(id)
+
+  bslib::layout_sidebar(
+    sidebar = bslib::sidebar(
+      width_slider(ns),
+      actionButton(ns("update"), "Update", class = "btn-primary")
+    ),
+    result_cards(ns)
+  )
+}
+
+countsServer <- function(id) {
+  moduleServer(id, function(input, output, session) {
+    counts_tbl <- reactive({
+      iris |>
+        dplyr::filter(Petal.Width >= input$min_width) |>
+        dplyr::group_by(Species) |>
+        dplyr::summarise(flowers = dplyr::n(), mean_sepal_width = mean(Sepal.Width))
+    }) |>
+      bindEvent(input$update, ignoreNULL = FALSE)
+
+    register_reactives(counts_tbl)
+
+    output$table <- renderTable(counts_tbl())
+    output$code <- renderText(reprex_reactive(counts_tbl)) |>
+      bindEvent(counts_tbl())
+
+    counts_tbl
+  })
+}
+
+#### UI ####
 ui <- bslib::page_navbar(
   title = "shinyreprex",
 
-  bslib::nav_panel(
-    "Reproduce",
-    bslib::layout_sidebar(
-      sidebar = bslib::sidebar(
-        sliderInput(
-          "min_width",
-          "Minimum petal width",
-          min(iris$Petal.Width),
-          max(iris$Petal.Width),
-          min(iris$Petal.Width),
-          step = 0.1
-        ),
-        selectInput(
-          "summary_fn",
-          "Summary function",
-          c(Mean = "mean", Median = "median", `Std. dev` = "sd")
-        ),
-        checkboxGroupInput(
-          "columns",
-          "Columns to summarise",
-          c("Sepal.Length", "Sepal.Width", "Petal.Length"),
-          selected = "Sepal.Width"
-        ),
-        actionButton("update", "Update", class = "btn-primary")
-      ),
-      bslib::layout_columns(
-        bslib::card(bslib::card_header("Output"), tableOutput("table")),
-        bslib::card(bslib::card_header("Reproducible script"), verbatimTextOutput("code"))
-      )
-    )
-  ),
-
-  bslib::nav_panel(
-    "Environment",
-    bslib::card(
-      bslib::card_header("Choose what to pin"),
-      p(
-        "The packages below were detected in the reactive by ", code("reprex_packages()"),
-        ". Narrow the selection, or add a package the detector could not see, then ",
-        "download a lockfile scoped to that choice."
-      ),
-      uiOutput("package_picker"),
-      downloadButton("custom_lock", "Download selected", class = "btn-secondary")
-    )
-  ),
+  bslib::nav_panel("Summary (purrr)", summaryUI("summary")),
+  bslib::nav_panel("Counts (dplyr)", countsUI("counts")),
 
   bslib::nav_spacer(),
-  bslib::nav_item(lockfileUI("lock", "Download renv.lock"))
+  bslib::nav_menu(
+    "Options",
+    icon = shiny::icon("cog"),
+    align = "right",
+    bslib::nav_item(
+      checkboxGroupInput("packages", "Select Packages", choices = NULL, selected = NULL)
+    ),
+    bslib::nav_item(
+      downloadLink("lockfile", "Download renv.lock", class = "dropdown-item")
+    )
+  )
 )
 
+#### Server ####
 server <- function(input, output, session) {
-  iris_filt <- reactive({
-    iris[iris$Petal.Width >= input$min_width, ]
-  }) |>
-    bindEvent(input$update, ignoreNULL = FALSE)
-
-  summary_tbl <- reactive({
-    purrr::map(
-      input$columns,
-      dat = iris_filt(),
-      fn = input$summary_fn,
-      \(col, dat, fn) {
-        aggregate(as.formula(paste(col, "~ Species")), data = dat, FUN = get(fn))
-      }
-    ) |>
-      purrr::reduce(merge, by = "Species")
-  }) |>
-    bindEvent(input$update, ignoreNULL = FALSE)
-
-  output$table <- renderTable(summary_tbl())
-
-  # Bound to the reactive so the script only refreshes when the output does.
-  output$code <- renderText(reprex_reactive(summary_tbl)) |>
-    bindEvent(summary_tbl())
-
-  # 1. The drop-in: one control in the navbar, pinning everything detected.
-  lockfileServer("lock", summary_tbl)
-
-  # 2. The custom path: same engine, user-selected packages.
-  detected <- reactive(reprex_packages(summary_tbl)) |>
-    bindEvent(summary_tbl())
-
-  output$package_picker <- renderUI({
-    checkboxGroupInput("packages", NULL, choices = detected(), selected = detected())
+  summary_tbl <- summaryServer("summary", c("Sepal.Length", "Sepal.Width"))
+  counts_tbl <- countsServer("counts")
+
+  detected <- reactive(reprex_packages())
+
+  observe({
+    updateCheckboxGroupInput(
+      session = session,
+      inputId = "packages",
+      choices = detected(),
+      selected = detected()
+    )
   })
 
-  output$custom_lock <- downloadHandler(
+  output$lockfile <- downloadHandler(
     filename = function() "renv.lock",
     content = function(file) {
-      reprex_lockfile(summary_tbl, packages = input$packages, lockfile = file)
+      withProgress(message = "Resolving package versions", {
+        reprex_lockfile(packages = input$packages, lockfile = file)
+      })
     }
   )
 }
diff --git a/tests/testthat/test-examples-shiny.R b/tests/testthat/test-examples-shiny.R
index ca9a61e..9424120 100644
--- a/tests/testthat/test-examples-shiny.R
+++ b/tests/testthat/test-examples-shiny.R
@@ -4,47 +4,66 @@ app_dir <- function(name) {
   path
 }
 
-test_that("The lockfile example app generates a script that reproduces its own output", {
+set_module_inputs <- function(session) {
+  session$setInputs(
+    `summary-min_width` = 0.5,
+    `summary-summary_fn` = "median",
+    `summary-update` = 1,
+    `counts-min_width` = 1,
+    `counts-update` = 1
+  )
+}
+
+test_that("Each module in the example app generates a script that reproduces its own table", {
   skip_if_not_installed("shiny")
+  skip_if_not_installed("dplyr")
 
   shiny::testServer(app_dir("lockfile"), {
-    session$setInputs(
-      min_width  = 0.5,
-      summary_fn = "median",
-      columns    = c("Sepal.Width", "Petal.Length"),
-      update     = 1
+    set_module_inputs(session)
+
+    expect_equal(
+      eval(parse(text = output$`summary-code`), envir = new.env()),
+      summary_tbl()
     )
+    expect_equal(
+      eval(parse(text = output$`counts-code`), envir = new.env()),
+      counts_tbl()
+    )
+  })
+})
+
+test_that("Each module reports only the packages its own reactive uses", {
+  skip_if_not_installed("shiny")
+  skip_if_not_installed("dplyr")
+
+  shiny::testServer(app_dir("lockfile"), {
+    set_module_inputs(session)
 
     expect_identical(reprex_packages(summary_tbl), "purrr")
-    expect_identical(
-      eval(parse(text = output$code), envir = new.env()),
-      summary_tbl()
+    expect_identical(reprex_packages(counts_tbl), "dplyr")
+
+    # A no-argument call reads the registry, covering both modules at once.
+    expect_named(
+      registered_reactives(session),
+      c("summary-summary_tbl", "counts-counts_tbl")
     )
+    expect_setequal(reprex_packages(), c("purrr", "dplyr"))
   })
 })
 
-test_that("The lockfile example app offers a restorable lockfile from both the module and the custom picker", {
+test_that("The example app offers a restorable lockfile covering both modules", {
   skip_on_cran()
   skip_if_not_installed("shiny")
+  skip_if_not_installed("dplyr")
   skip_if_not_installed("renv")
 
   shiny::testServer(app_dir("lockfile"), {
-    session$setInputs(
-      min_width  = 0.5,
-      summary_fn = "median",
-      columns    = "Sepal.Width",
-      update     = 1,
-      packages   = "purrr"
-    )
+    set_module_inputs(session)
 
     # Reading a download output runs its content function and returns the path.
-    for (lock in c(output$`lock-download`, output$custom_lock)) {
-      parsed <- renv::lockfile_read(lock)
-      expect_identical(parsed$R$Version, as.character(getRversion()))
-      expect_identical(
-        parsed$Packages$purrr$Version,
-        as.character(utils::packageVersion("purrr"))
-      )
-    }
+    parsed <- renv::lockfile_read(output$lockfile)
+
+    expect_identical(parsed$R$Version, as.character(getRversion()))
+    expect_true(all(c("purrr", "dplyr") %in% names(parsed$Packages)))
   })
 })

From ecb00c7d7a6437139652df7194936bcb395538e2 Mon Sep 17 00:00:00 2001
From: Ashley Baldry <arbaldry91@gmail.com>
Date: Mon, 31 Aug 2026 14:20:14 +0100
Subject: [PATCH 06/10] Updating layout of lockfile example app

---
 R/reprex_lockfile.R                   |  5 +++-
 inst/examples-shiny/lockfile/app.R    | 43 +++++++++++++++++----------
 tests/testthat/test-reprex_lockfile.R | 29 ++++++++++++++++++
 3 files changed, 60 insertions(+), 17 deletions(-)

diff --git a/R/reprex_lockfile.R b/R/reprex_lockfile.R
index ca5941a..d69c811 100644
--- a/R/reprex_lockfile.R
+++ b/R/reprex_lockfile.R
@@ -123,10 +123,13 @@ reprex_lockfile <- function(...,
                             session = shiny::getDefaultReactiveDomain()) {
   if (is.null(packages)) {
     packages <- reprex_packages(..., session = session)
+    detect_term <- "detected"
+  } else {
+    detect_term <- "selected"
   }
 
   if (length(packages) == 0L) {
-    cli::cli_warn("No non-base packages detected; the lockfile will record only the R version")
+    cli::cli_warn("No non-base packages {detect_term}; the lockfile will record only the R version")
   }
 
   # Snapshot against a throwaway project so renv never writes infrastructure
diff --git a/inst/examples-shiny/lockfile/app.R b/inst/examples-shiny/lockfile/app.R
index 392df61..95ccfa2 100644
--- a/inst/examples-shiny/lockfile/app.R
+++ b/inst/examples-shiny/lockfile/app.R
@@ -107,22 +107,31 @@ countsServer <- function(id) {
 #### UI ####
 ui <- bslib::page_navbar(
   title = "shinyreprex",
-
-  bslib::nav_panel("Summary (purrr)", summaryUI("summary")),
-  bslib::nav_panel("Counts (dplyr)", countsUI("counts")),
-
-  bslib::nav_spacer(),
-  bslib::nav_menu(
-    "Options",
-    icon = shiny::icon("cog"),
-    align = "right",
-    bslib::nav_item(
-      checkboxGroupInput("packages", "Select Packages", choices = NULL, selected = NULL)
+  header = bslib::card(
+    fill = FALSE,
+    class = "mx-4 my-2",
+    bslib::card_header("About"),
+    p(
+      class = "mb-0 text-body-secondary",
+      "Each tab is a module that registers its own reactive with ",
+      code("register_reactives()"), ", so their scripts carry different ",
+      code("library()"), " calls. One lockfile pins the union of both."
     ),
-    bslib::nav_item(
-      downloadLink("lockfile", "Download renv.lock", class = "dropdown-item")
+    div(
+      class = "d-flex align-items-center",
+      div(
+        class = "mx-3",
+        checkboxGroupInput("packages", "Include in lockfile", inline = TRUE)
+      ),
+      div(
+        class = "mx-3",
+        downloadButton("lockfile", "Download renv.lock", class = "btn-primary")
+      )
     )
-  )
+  ),
+
+  bslib::nav_panel("Summary (purrr)", summaryUI("summary")),
+  bslib::nav_panel("Counts (dplyr)", countsUI("counts"))
 )
 
 #### Server ####
@@ -137,9 +146,11 @@ server <- function(input, output, session) {
       session = session,
       inputId = "packages",
       choices = detected(),
-      selected = detected()
+      selected = detected(),
+      inline = TRUE
     )
-  })
+  }) |>
+    bindEvent(detected(), once = TRUE)
 
   output$lockfile <- downloadHandler(
     filename = function() "renv.lock",
diff --git a/tests/testthat/test-reprex_lockfile.R b/tests/testthat/test-reprex_lockfile.R
index c7a5a35..7d07034 100644
--- a/tests/testthat/test-reprex_lockfile.R
+++ b/tests/testthat/test-reprex_lockfile.R
@@ -21,6 +21,35 @@ test_that("A non-reactive object passed to reprex_packages errors", {
 })
 
 #### reprex_lockfile ####
+test_that("An empty package set warns differently depending on whether it was detected or selected", {
+  skip_on_cran()
+  skip_if_not_installed("renv")
+
+  test_server <- function(input, output, session) {
+    base_only <- reactive(nrow(iris))
+    with_purrr <- reactive(purrr::keep(iris, is.numeric))
+  }
+
+  lock <- tempfile(fileext = ".lock")
+  on.exit(unlink(lock), add = TRUE)
+
+  shiny::testServer(test_server, {
+    # Nothing found in the reactive itself.
+    expect_warning(
+      reprex_lockfile(base_only, lockfile = lock),
+      "No non-base packages detected",
+      fixed = TRUE
+    )
+
+    # Packages were available, but the caller narrowed them away.
+    expect_warning(
+      reprex_lockfile(with_purrr, packages = character(), lockfile = lock),
+      "No non-base packages selected",
+      fixed = TRUE
+    )
+  })
+})
+
 test_that("A restorable lockfile is written covering the reactive's packages", {
   skip_on_cran()
 

From 2eb54f23bcc685f2c483f343e5011afb5615bbb1 Mon Sep 17 00:00:00 2001
From: Ashley Baldry <arbaldry91@gmail.com>
Date: Mon, 31 Aug 2026 14:24:52 +0100
Subject: [PATCH 07/10] Add exclusions for lintr configuration

---
 .github/linters/.lintr | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/.github/linters/.lintr b/.github/linters/.lintr
index c5aa6ca..6c770f1 100644
--- a/.github/linters/.lintr
+++ b/.github/linters/.lintr
@@ -3,3 +3,6 @@ linters: linters_with_defaults(
   object_name_linter = NULL
   ) # see vignette("lintr")
 encoding: "UTF-8"
+exclusions: list(
+    "inst/examples-shiny"
+  )

From 5ae9755f0e29df3a14e349ca794b253b91c0e4f2 Mon Sep 17 00:00:00 2001
From: Ashley Baldry <arbaldry91@gmail.com>
Date: Mon, 31 Aug 2026 14:26:07 +0100
Subject: [PATCH 08/10] Update detect_term assignment for clarity

---
 R/reprex_lockfile.R | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/R/reprex_lockfile.R b/R/reprex_lockfile.R
index d69c811..44d398e 100644
--- a/R/reprex_lockfile.R
+++ b/R/reprex_lockfile.R
@@ -123,9 +123,9 @@ reprex_lockfile <- function(...,
                             session = shiny::getDefaultReactiveDomain()) {
   if (is.null(packages)) {
     packages <- reprex_packages(..., session = session)
-    detect_term <- "detected"
+    detect_term <- "detected" #nolint
   } else {
-    detect_term <- "selected"
+    detect_term <- "selected" #nolint
   }
 
   if (length(packages) == 0L) {

From 01205881b751cde1112cc0228d1a6a1297108fd9 Mon Sep 17 00:00:00 2001
From: Ashley Baldry <arbaldry91@gmail.com>
Date: Mon, 31 Aug 2026 14:27:14 +0100
Subject: [PATCH 09/10] Update skip function to use testthat namespace

---
 tests/testthat/test-examples-shiny.R | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/testthat/test-examples-shiny.R b/tests/testthat/test-examples-shiny.R
index 9424120..59fe2f4 100644
--- a/tests/testthat/test-examples-shiny.R
+++ b/tests/testthat/test-examples-shiny.R
@@ -1,6 +1,6 @@
 app_dir <- function(name) {
   path <- system.file("examples-shiny", name, package = "shinyreprex")
-  if (!nzchar(path)) skip(paste0("Example app '", name, "' is not installed"))
+  if (!nzchar(path)) testthat::skip(paste0("Example app '", name, "' is not installed"))
   path
 }
 

From 547edb78a3566d481bbab7eeb021ef01a71baeb4 Mon Sep 17 00:00:00 2001
From: Ashley Baldry <arbaldry91@gmail.com>
Date: Mon, 31 Aug 2026 14:50:41 +0100
Subject: [PATCH 10/10] (lint): fix lints

---
 .github/linters/.lintr | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/.github/linters/.lintr b/.github/linters/.lintr
index 6c770f1..70a8e9f 100644
--- a/.github/linters/.lintr
+++ b/.github/linters/.lintr
@@ -3,6 +3,7 @@ linters: linters_with_defaults(
   object_name_linter = NULL
   ) # see vignette("lintr")
 encoding: "UTF-8"
+# Exclusion paths are resolved relative to this file, not the package root
 exclusions: list(
-    "inst/examples-shiny"
+    "../../inst/examples-shiny"
   )