diff --git a/.Rbuildignore b/.Rbuildignore
index efb7e88..edfd5b9 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -1,3 +1,4 @@
+^.*\.Rcheck/$
 ^.*\.Rproj$
 ^\.Rproj\.user$
 ^_pkgdown\.yml$
@@ -22,3 +23,4 @@
 ^Makefile$
 ^codecov\.yml$
 ^pkgdown$
+^cran-comments\.md$
diff --git a/.gitignore b/.gitignore
index 686258f..6382407 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,6 +13,7 @@ docs/
 /doc/
 /Meta/
 ..Rcheck/
+*.Rcheck/
 .claude
 .codex
 .agents
diff --git a/DESCRIPTION b/DESCRIPTION
index 465cb28..2e004e9 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: Immutables
 Type: Package
 Title: Fast and Functional Data Structures
-URL: https://oneilsh.github.io/immutables, https://github.com/oneilsh/immutables
+URL: https://oneilsh.github.io/immutables/, https://github.com/oneilsh/immutables
 BugReports: https://github.com/oneilsh/immutables/issues
 Version: 1.0.0
 Authors@R: c(
@@ -12,6 +12,8 @@ Description: Provides fast, side-effect free data structures, including
     sequences, and interval indices.
 License: MIT + file LICENSE
 Encoding: UTF-8
+Depends:
+    R (>= 4.1.0)
 Imports:
     coro,
     Rcpp,
@@ -38,4 +40,4 @@ Suggests:
 Config/testthat/edition: 3
 VignetteBuilder: knitr
 Roxygen: list(markdown = TRUE)
-RoxygenNote: 7.3.2
+RoxygenNote: 7.3.3
diff --git a/NEWS.md b/NEWS.md
index b0e5598..66296aa 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,3 +1,7 @@
-# immutables 1.0.0
+# Immutables 1.0.0
 
-* First release.
+* First CRAN submission.
+* `flexseq`s: list-like sequences with push/pop/peek from either end, indexed and named access, insertion, splitting, and concatenation.
+* `priority_queue`s, `ordered_sequence`s, `interval_index`es: finger-tree-backed structures for min/max-by-priority, sorted-by-key, and interval-overlap queries.
+* Developer API for building custom structures via monoid/measure combinations.
+* Core operations implemented in C++ via Rcpp, with matching pure-R reference implementations using `lambda.r`.
diff --git a/R/30-api-flexseq-core.R b/R/30-api-flexseq-core.R
index 6f25952..207e73b 100644
--- a/R/30-api-flexseq-core.R
+++ b/R/30-api-flexseq-core.R
@@ -284,7 +284,8 @@ merge.flexseq <- function(x, y, ...) {
 #' x <- flexseq("a", "b", "c")
 #' if(requireNamespace("igraph", quietly = TRUE)) plot(x)
 #'
-#' \dontrun{
+#' if (requireNamespace("igraph", quietly = TRUE)) {
+#' \donttest{
 #' # Label every node with its subtree size (leaves contribute 1).
 #' plot_structure(as_flexseq(1:10), node_label = function(node) {
 #'   paste0(node$type, "\n.size=", node$measures$.size)
@@ -296,8 +297,8 @@ merge.flexseq <- function(x, y, ...) {
 #' xs <- add_monoids(as_flexseq(c(3, 1, 4, 1, 5, 9, 2, 6)),
 #'                   list(sum = sum_monoid))
 #' plot_structure(xs, node_label = function(node) {
-#'   if(node$type == "Element") sprintf("%g\nΣ=%g", node$element, node$measures$sum)
-#'   else sprintf("%s\nΣ=%g", node$type, node$measures$sum)
+#'   if(node$type == "Element") sprintf("%g\nsum=%g", node$element, node$measures$sum)
+#'   else sprintf("%s\nsum=%g", node$type, node$measures$sum)
 #' })
 #'
 #' # List-valued built-in measure: priority_queue's .pq_min tracks the min
@@ -315,6 +316,7 @@ merge.flexseq <- function(x, y, ...) {
 #'   }
 #' })
 #' }
+#' }
 #' @export
 # Runtime: O(n) to build plot graph data.
 plot.flexseq <- function(x, ...) {
diff --git a/R/70-plotting.R b/R/70-plotting.R
index c4db4be..c8543f7 100644
--- a/R/70-plotting.R
+++ b/R/70-plotting.R
@@ -267,7 +267,8 @@ NULL
 #' @return Invoked for its side effect (draws to the active graphics
 #'   device). Returns `NULL` invisibly.
 #' @examples
-#' \dontrun{
+#' if (requireNamespace("igraph", quietly = TRUE)) {
+#' \donttest{
 #' t <- as_flexseq(letters[1:8])
 #' plot_structure(t, title = "Finger tree")
 #'
@@ -277,10 +278,11 @@ NULL
 #' xs <- add_monoids(as_flexseq(c(3, 1, 4, 1, 5, 9, 2, 6)),
 #'                   list(sum = sum_monoid))
 #' plot_structure(xs, node_label = function(node) {
-#'   if(node$type == "Element") sprintf("%g\nΣ=%g", node$element, node$measures$sum)
-#'   else sprintf("%s\nΣ=%g", node$type, node$measures$sum)
+#'   if(node$type == "Element") sprintf("%g\nsum=%g", node$element, node$measures$sum)
+#'   else sprintf("%s\nsum=%g", node$type, node$measures$sum)
 #' })
 #' }
+#' }
 #' @seealso [plot.flexseq()], [measure_monoid()], [add_monoids()]
 #' @export
 # Runtime: O(n) to build graph structures prior to plotting.
diff --git a/R/immutables-package.R b/R/immutables-package.R
index c6ff451..1b0bddc 100644
--- a/R/immutables-package.R
+++ b/R/immutables-package.R
@@ -1,28 +1,28 @@
-#' immutables
-#' 
-#' The `immutables` R package implements several immutable, or persistent, data
+#' Immutables: Fast and Functional Data Structures
+#'
+#' The `Immutables` R package implements several immutable, or persistent, data
 #' structures: operations return modified copies while remaining fast and true
 #' to R's side-effect-free functional nature.
 #'
-#' - `flexseq`s provide list-like operations including indexed and named element
-#'    access, push/pop/peek from either end for double-ended queue behavior, 
-#'    insertion, splitting, and concatenation.
-#' - `priority_queues` associate items with priority values and provide
+#' - `flexseq`s provide list-like operations: indexed and named element access;
+#'   push/pop/peek from either end for double-ended queue behavior; insertion,
+#'   splitting, and concatenation.
+#' - `priority_queue`s associate items with priority values and provide
 #'   min and max peek/pop by priority and fast insertion.
-#' - `ordered_sequences` associate items with key values and keep the elements in
+#' - `ordered_sequence`s associate items with key values and keep the elements in
 #'   sorted order by key. These may be similarly be inserted/popped/peeked by key
 #'   value as well as position. Keys may be duplicated, with first-in-first-out order within key groups.
-#' - `interval_indexes` store items associated with interval ranges, supporting
+#' - `interval_index`es store items associated with interval ranges, supporting
 #'   point as well as interval overlaps/contains/within queries. Items are kept
 #'   in start-order enabling ordered sequence operations and sweep-line
 #'   algorithms.
 #'
 #' Backed by monoid-annotated 2-3 fingertrees as described by
-#' [Hinze and Paterson](https://doi.org/10.1017/S0956796805005769), most operations are constant time, amortized constant time, or $O(\\log(n))$ (indexing $k$ elements is $O(k \\log(n))$). Core functions are implemented in C++ (via Rcpp) for speed, with matching pure-R reference implementations using `lambda.r` syntax to match the paper.
+#' Hinze and Paterson, most operations are constant time, amortized constant time, or $O(\\log(n))$. Core functions are implemented in C++ (via Rcpp) for speed, with matching pure-R reference implementations using `lambda.r` syntax to match the paper.
 #'
-#' Finally, the developer API supports the addition of custom structures via combinations of monoids and measures; see vignettes for details.
+#' Finally, the developer API supports the addition of custom structures via combinations of monoids and measures.
 #'
-#' - Hinze, R. and Paterson, R. (2006), *Finger trees: a simple general-purpose data structure*.
+#' - Hinze, R. and Paterson, R. (2006), *Finger trees: a simple general-purpose data structure*. \doi{10.1017/S0956796805005769}
 #'
 #' @keywords internal
 #' @import lambda.r
diff --git a/cran-comments.md b/cran-comments.md
new file mode 100644
index 0000000..62ad3e7
--- /dev/null
+++ b/cran-comments.md
@@ -0,0 +1,19 @@
+## R CMD check results
+
+0 errors | 0 warnings | 1 note
+
+The NOTE has two components:
+
+* "New submission" is expected
+* "catenable" is flagged as a possibly misspelled word but is standard
+terminology in functional data structures literature
+
+## Test environments
+
+- local macOS (aarch64), R 4.5.3
+- win-builder R-devel (R 4.6.0 RC, x86_64-w64-mingw32)
+- GitHub Actions: ubuntu-latest, macos-latest, windows-latest
+
+## Notes
+
+This is a new submission.
diff --git a/man/Immutables-package.Rd b/man/Immutables-package.Rd
index 61c1161..7662eb2 100644
--- a/man/Immutables-package.Rd
+++ b/man/Immutables-package.Rd
@@ -4,40 +4,40 @@
 \name{Immutables-package}
 \alias{Immutables}
 \alias{Immutables-package}
-\title{immutables}
+\title{Immutables: Fast and Functional Data Structures}
 \description{
-The \code{immutables} R package implements several immutable, or persistent, data
+The \code{Immutables} R package implements several immutable, or persistent, data
 structures: operations return modified copies while remaining fast and true
 to R's side-effect-free functional nature.
 }
 \details{
 \itemize{
-\item \code{flexseq}s provide list-like operations including indexed and named element
-access, push/pop/peek from either end for double-ended queue behavior,
-insertion, splitting, and concatenation.
-\item \code{priority_queues} associate items with priority values and provide
+\item \code{flexseq}s provide list-like operations: indexed and named element access;
+push/pop/peek from either end for double-ended queue behavior; insertion,
+splitting, and concatenation.
+\item \code{priority_queue}s associate items with priority values and provide
 min and max peek/pop by priority and fast insertion.
-\item \code{ordered_sequences} associate items with key values and keep the elements in
+\item \code{ordered_sequence}s associate items with key values and keep the elements in
 sorted order by key. These may be similarly be inserted/popped/peeked by key
 value as well as position. Keys may be duplicated, with first-in-first-out order within key groups.
-\item \code{interval_indexes} store items associated with interval ranges, supporting
+\item \code{interval_index}es store items associated with interval ranges, supporting
 point as well as interval overlaps/contains/within queries. Items are kept
 in start-order enabling ordered sequence operations and sweep-line
 algorithms.
 }
 
 Backed by monoid-annotated 2-3 fingertrees as described by
-\href{https://doi.org/10.1017/S0956796805005769}{Hinze and Paterson}, most operations are constant time, amortized constant time, or $O(\\log(n))$ (indexing $k$ elements is $O(k \\log(n))$). Core functions are implemented in C++ (via Rcpp) for speed, with matching pure-R reference implementations using \code{lambda.r} syntax to match the paper.
+Hinze and Paterson, most operations are constant time, amortized constant time, or $O(\\log(n))$. Core functions are implemented in C++ (via Rcpp) for speed, with matching pure-R reference implementations using \code{lambda.r} syntax to match the paper.
 
-Finally, the developer API supports the addition of custom structures via combinations of monoids and measures; see vignettes for details.
+Finally, the developer API supports the addition of custom structures via combinations of monoids and measures.
 \itemize{
-\item Hinze, R. and Paterson, R. (2006), \emph{Finger trees: a simple general-purpose data structure}.
+\item Hinze, R. and Paterson, R. (2006), \emph{Finger trees: a simple general-purpose data structure}. \doi{10.1017/S0956796805005769}
 }
 }
 \seealso{
 Useful links:
 \itemize{
-  \item \url{https://oneilsh.github.io/immutables}
+  \item \url{https://oneilsh.github.io/immutables/}
   \item \url{https://github.com/oneilsh/immutables}
   \item Report bugs at \url{https://github.com/oneilsh/immutables/issues}
 }
diff --git a/man/plot.flexseq.Rd b/man/plot.flexseq.Rd
index 435b85c..e61cc49 100644
--- a/man/plot.flexseq.Rd
+++ b/man/plot.flexseq.Rd
@@ -54,7 +54,8 @@ built-in \code{.pq_min} on \code{priority_queue} is \code{list(has, priority)}).
 x <- flexseq("a", "b", "c")
 if(requireNamespace("igraph", quietly = TRUE)) plot(x)
 
-\dontrun{
+if (requireNamespace("igraph", quietly = TRUE)) {
+\donttest{
 # Label every node with its subtree size (leaves contribute 1).
 plot_structure(as_flexseq(1:10), node_label = function(node) {
   paste0(node$type, "\n.size=", node$measures$.size)
@@ -66,8 +67,8 @@ sum_monoid <- measure_monoid(`+`, 0, function(el) el)
 xs <- add_monoids(as_flexseq(c(3, 1, 4, 1, 5, 9, 2, 6)),
                   list(sum = sum_monoid))
 plot_structure(xs, node_label = function(node) {
-  if(node$type == "Element") sprintf("\%g\nΣ=\%g", node$element, node$measures$sum)
-  else sprintf("\%s\nΣ=\%g", node$type, node$measures$sum)
+  if(node$type == "Element") sprintf("\%g\nsum=\%g", node$element, node$measures$sum)
+  else sprintf("\%s\nsum=\%g", node$type, node$measures$sum)
 })
 
 # List-valued built-in measure: priority_queue's .pq_min tracks the min
@@ -86,3 +87,4 @@ plot_structure(pq, node_label = function(node) {
 })
 }
 }
+}
diff --git a/man/plot_structure.Rd b/man/plot_structure.Rd
index 3124fec..3b2e0fa 100644
--- a/man/plot_structure.Rd
+++ b/man/plot_structure.Rd
@@ -92,7 +92,8 @@ access to the full \code{node_label} API for custom label formatting. Requires
 the \code{igraph} package (listed in \code{Suggests}).
 }
 \examples{
-\dontrun{
+if (requireNamespace("igraph", quietly = TRUE)) {
+\donttest{
 t <- as_flexseq(letters[1:8])
 plot_structure(t, title = "Finger tree")
 
@@ -102,11 +103,12 @@ sum_monoid <- measure_monoid(`+`, 0, function(el) el)
 xs <- add_monoids(as_flexseq(c(3, 1, 4, 1, 5, 9, 2, 6)),
                   list(sum = sum_monoid))
 plot_structure(xs, node_label = function(node) {
-  if(node$type == "Element") sprintf("\%g\nΣ=\%g", node$element, node$measures$sum)
-  else sprintf("\%s\nΣ=\%g", node$type, node$measures$sum)
+  if(node$type == "Element") sprintf("\%g\nsum=\%g", node$element, node$measures$sum)
+  else sprintf("\%s\nsum=\%g", node$type, node$measures$sum)
 })
 }
 }
+}
 \seealso{
 \code{\link[=plot.flexseq]{plot.flexseq()}}, \code{\link[=measure_monoid]{measure_monoid()}}, \code{\link[=add_monoids]{add_monoids()}}
 }