Say in the app that it has been updated since the paper

The header links to a 'What changed' note built from the configuration: this
version and date, the version and model the paper describes, and why the two
differ. The README gains a version table.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

R/config.R

@@ -13,6 +13,16 @@ get_extraction_model = function() {
   if (nchar(model) == 0) DEFAULT_EXTRACTION_MODEL else model
 }
 
+# Version of this app, shown in the header and in the "What changed" help
+APP_VERSION_NUMBER = "3.0.0"
+APP_VERSION_DATE = "9 October 2026"
+
+# The version that the paper describes. The app has been updated since the
+# paper was drafted, and the "What changed" help says so. PAPER_MODEL is a
+# record of the past, not a setting: nothing is sent to it.
+PAPER_VERSION_NUMBER = "2.0.1"
+PAPER_MODEL = "gpt-5-mini"
+
 # Name of the provider behind ellmer::chat_openai(), used in UI text
 MODEL_PROVIDER = "OpenAI"
 
@@ -50,6 +60,10 @@ app_config = function() {
     max_pages_or_images = MAX_PAGES_OR_IMAGES,
     max_upload_mb = MAX_UPLOAD_MB,
     max_fields = MAX_FIELDS,
-    list_separator = LIST_SEPARATOR
+    list_separator = LIST_SEPARATOR,
+    version = APP_VERSION_NUMBER,
+    version_date = APP_VERSION_DATE,
+    paper_version = PAPER_VERSION_NUMBER,
+    paper_model = PAPER_MODEL
   )
 }

R/help.R

@@ -1,7 +1,7 @@
 # Help text for the "?" buttons. Every number and name in the text comes from
 # app_config(), the same values that drive the app's behaviour.
 
-HELP_TOPICS = c("source", "fields", "extract", "results")
+HELP_TOPICS = c("source", "fields", "extract", "results", "changes")
 
 # Returns list(title, paragraphs) for one help topic
 help_content = function(topic, cfg = app_config()) {
@@ -73,6 +73,21 @@ help_content = function(topic, cfg = app_config()) {
         "Download as CSV saves the table with the source_id, status and status_message columns. Reproduce in code shows R and Python code that runs the same extraction, with your fields and the same model, on your own data."
       )
     ),
+    changes = list(
+      title = "What changed since the paper",
+      paragraphs = c(
+        sprintf(
+          "This is version %s of the app, released on %s. The paper describes version %s, which used the %s model %s.",
+          cfg$version, cfg$version_date, cfg$paper_version, cfg$provider, cfg$paper_model
+        ),
+        sprintf(
+          "The model is now %s. If the screen or the model you see here differs from the paper, that is why.",
+          cfg$model
+        ),
+        "Other changes: ready-made field templates for common quality documents; field definitions that can be saved and loaded; a progress bar, with one failed item no longer discarding the rest; R and Python code that reproduces an extraction; and a '?' beside each step that explains how it works.",
+        "The difference is intentional. Language models are replaced often, and users find problems that only appear in use. An app built on a language model needs regular updating, and a paper can only describe it at one point in time."
+      )
+    ),
     stop("Unknown help topic: ", topic)
   )
 }
@@ -90,6 +105,12 @@ help_button = function(topic) {
   )
 }
 
+# Link in the header that opens the "What changed" help
+changes_link = function() {
+  shiny::actionLink("help_changes", "Updated since the paper. What changed?",
+                    class = "changes-link", `aria-haspopup` = "dialog")
+}
+
 # Modal dialog with the help for a topic
 help_modal = function(topic, cfg = app_config()) {
   content = help_content(topic, cfg)

README.md

@@ -74,7 +74,20 @@ one item per row of its first column, and its first row is treated as a header.
 The model id is set in one place, `DEFAULT_EXTRACTION_MODEL` in `R/config.R`. To use another
 OpenAI model without editing code, set the environment variable `EXTRACTION_MODEL`. The
 call, the help text and the generated code all read this value. A test fails if a model id
-is written anywhere else in the app code.
+is written anywhere else in the app code, apart from the record of the model that the
+paper's version used.
+
+## Versions
+
+| Version | Date | Model | Notes |
+|---|---|---|---|
+| 3.0.0 | 9 October 2026 | `gpt-6-luna` | Released after the paper was drafted. Field templates, saved field definitions, per-item progress and failure handling, code that reproduces an extraction, and in-app help. |
+| 2.0.1 | 2026 | `gpt-5-mini` | The version the paper describes. |
+
+The app has been updated since the paper was drafted, and this is intentional. Language
+models are replaced often, and users find problems that only appear in use, so an app built
+on a language model needs regular updating. The header of the app links to a short "What
+changed" note that is generated from the values in `R/config.R`.
 
 ## Run it yourself
 

app.R

@@ -17,7 +17,7 @@ options(shiny.maxRequestSize = MAX_UPLOAD_MB * 1024^2)
 # Model used for every call and named in every piece of UI text
 EXTRACTION_MODEL = get_extraction_model()
 
-APP_VERSION = "Version 3.0.0 | October 2026"
+APP_VERSION = paste0("Version ", APP_VERSION_NUMBER, " | ", APP_VERSION_DATE)
 
 PAPER_TITLE = "What Quality Engineers Need to Know About Generative AI: Structured Data Extraction"
 
@@ -83,7 +83,7 @@ ui = shiny::fluidPage(
       ),
       shiny::div(
         class = "header-right",
-        shiny::p(APP_VERSION),
+        shiny::p(APP_VERSION, " | ", changes_link()),
         shiny::p(
           shiny::tags$strong("Authors: "),
           "Fadel M. Megahed, Ying-Ju Chen, Yamin Dahwich, Arthur Carvalho, L. Allison Jones-Farmer, Ibrahim Yousif, and Inez M. Zwetsloot"

tests/testthat/test-config-help.R

@@ -48,11 +48,12 @@ test_that("no model id is written outside R/config.R", {
     )
   }
 
-  # In the config file, the only model id is the default
+  # In the config file, the only model ids are the default and the record of
+  # the model that the paper's version used
   config_lines = readLines(config_file, warn = FALSE)
   hits = grep(model_pattern, config_lines, ignore.case = TRUE)
-  expect_length(hits, 1)
-  expect_match(config_lines[hits], "^DEFAULT_EXTRACTION_MODEL = ")
+  expect_length(hits, 2)
+  expect_match(config_lines[hits], "^(DEFAULT_EXTRACTION_MODEL|PAPER_MODEL) = ")
 })
 
 test_that("help text is generated from the configuration values", {
@@ -88,6 +89,18 @@ test_that("help text follows the configured model at run time", {
   expect_match(paste(help_content("source")$paragraphs, collapse = " "), "model-from-env")
 })
 
+test_that("the header says the app was updated since the paper, from the configuration", {
+  text = paste(help_content("changes")$paragraphs, collapse = " ")
+  for (value in c(APP_VERSION_NUMBER, APP_VERSION_DATE, PAPER_VERSION_NUMBER, PAPER_MODEL, get_extraction_model())) {
+    expect_match(text, value, fixed = TRUE)
+  }
+  withr::local_envvar(EXTRACTION_MODEL = "model-from-env")
+  expect_match(paste(help_content("changes")$paragraphs, collapse = " "), "model-from-env")
+  link = as.character(changes_link())
+  expect_match(link, "id=\"help_changes\"", fixed = TRUE)
+  expect_match(link, "What changed?", fixed = TRUE)
+})
+
 test_that("every help topic has content, a button and a dialog, without em dashes", {
   for (topic in HELP_TOPICS) {
     content = help_content(topic)

www/miami-theme.css

@@ -65,6 +65,11 @@ body {
   text-align: right;
 }
 
+.header-right .changes-link {
+  color: #EFDB72;
+  text-decoration: underline;
+}
+
 .header-right p {
   margin: 3px 0;
   font-size: 0.85em;