Add rebuild: republish an issue's EPUBs from its stored content

`daily-epub rebuild --date D` (and the rebuild-YYYY-MM-DD job) takes the
issues.issue_json snapshot and restores each article's body from its row.
It then builds both editions and the XTC, publishes them under the same
names and records the issue as a run would. Nothing is curated again or
refreshed from live rows, so headlines, summaries, social lines and rating
links stay as published; only images are downloaded again. It takes the
run lock, opens the database without migrating, and the job is marked
dangerous like generate.

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

src/jobs.rs

@@ -32,6 +32,8 @@ pub const EXITED_BEFORE_START: &str = "unit exited before the job started; see t
 pub enum Job {
     /// `generate` (today) or `generate-YYYY-MM-DD`.
     Generate { date: Option<Date> },
+    /// `rebuild-YYYY-MM-DD` → `rebuild --date`.
+    Rebuild { date: Date },
     /// `dry-run` → `generate --dry-run`.
     DryRun,
     /// `profile-rebuild` → `profile rebuild`.
@@ -70,8 +72,9 @@ impl Job {
                 .all(|byte| byte.is_ascii_lowercase() || byte.is_ascii_digit() || byte == b'-')
     }
 
-    /// Parse a catalogue name or the dated `generate-YYYY-MM-DD` form; anything
-    /// else (including `../x`, uppercase, unknown names) is `None`.
+    /// Parse a catalogue name or a dated `generate-YYYY-MM-DD` or
+    /// `rebuild-YYYY-MM-DD` form; anything else (including `../x`, uppercase,
+    /// unknown names) is `None`.
     pub fn parse(name: &str) -> Option<Job> {
         if !Self::valid_name(name) {
             return None;
@@ -86,10 +89,17 @@ impl Job {
             "import-ratings" => Some(Job::ImportRatings),
             "interests-categorize" => Some(Job::InterestsCategorize),
             _ => {
-                let date = name.strip_prefix("generate-")?;
+                let (rebuild, date) = match name.strip_prefix("generate-") {
+                    Some(date) => (false, date),
+                    None => (true, name.strip_prefix("rebuild-")?),
+                };
                 // Exactly `YYYY-MM-DD`; the round trip rejects `2026-9-3`.
                 let parsed: Date = date.parse().ok()?;
-                (parsed.to_string() == date).then_some(Job::Generate { date: Some(parsed) })
+                (parsed.to_string() == date).then_some(if rebuild {
+                    Job::Rebuild { date: parsed }
+                } else {
+                    Job::Generate { date: Some(parsed) }
+                })
             }
         }
     }
@@ -98,6 +108,7 @@ impl Job {
         match self {
             Job::Generate { date: None } => "generate".into(),
             Job::Generate { date: Some(date) } => format!("generate-{date}"),
+            Job::Rebuild { date } => format!("rebuild-{date}"),
             Job::DryRun => "dry-run".into(),
             Job::ProfileRebuild => "profile-rebuild".into(),
             Job::FeaturesBackfill => "features-backfill".into(),
@@ -121,6 +132,9 @@ impl Job {
             Job::Generate { date: Some(_) } => {
                 "Build and publish the issue of a given date, republishing it if it exists."
             }
+            Job::Rebuild { .. } => {
+                "Re-render and republish a published issue's EPUBs from its stored content, without curating again."
+            }
             Job::DryRun => "Run the whole pipeline but publish nothing and record no issue.",
             Job::ProfileRebuild => {
                 "Regenerate the learned taste adjustments from ratings with the editor model."
@@ -144,6 +158,7 @@ impl Job {
     pub fn takes_lock(&self) -> Option<&'static str> {
         match self {
             Job::Generate { .. } | Job::DryRun => Some("generate"),
+            Job::Rebuild { .. } => Some("rebuild"),
             Job::ProfileRebuild => Some("profile rebuild"),
             Job::FeaturesBackfill => Some("features backfill"),
             Job::BackfillSocial => Some("backfill-social"),
@@ -151,9 +166,9 @@ impl Job {
         }
     }
 
-    /// Needs a confirmation dialog: `generate` republishes an issue.
+    /// Needs a confirmation dialog: `generate` and `rebuild` republish an issue.
     pub fn dangerous(&self) -> bool {
-        matches!(self, Job::Generate { .. })
+        matches!(self, Job::Generate { .. } | Job::Rebuild { .. })
     }
 }
 
@@ -481,6 +496,24 @@ mod tests {
         assert!(!Job::parse("dry-run").unwrap().dangerous());
     }
 
+    #[test]
+    fn parse_accepts_the_dated_rebuild_form() {
+        let job = Job::parse("rebuild-2026-10-01").unwrap();
+        assert_eq!(
+            job,
+            Job::Rebuild {
+                date: "2026-10-01".parse().unwrap()
+            }
+        );
+        assert_eq!(job.name(), "rebuild-2026-10-01");
+        assert_eq!(job.unit(), "daily-epub-job@rebuild-2026-10-01.service");
+        assert_eq!(job.takes_lock(), Some("rebuild"));
+        assert!(job.dangerous());
+        for bad in ["rebuild", "rebuild-", "rebuild-2026-10-1", "rebuild-today"] {
+            assert_eq!(Job::parse(bad), None, "{bad}");
+        }
+    }
+
     #[test]
     fn parse_rejects_traversal_uppercase_and_unknown_names() {
         for name in [

src/main.rs

@@ -36,6 +36,8 @@ struct Cli {
 enum Command {
     /// Build (and publish) one issue.
     Generate(GenerateArgs),
+    /// Rebuild and republish a published issue's EPUBs from its stored content.
+    Rebuild(RebuildArgs),
     /// Run the rating endpoints, the OPDS catalog and downloads.
     Serve,
     /// Taste-profile maintenance.
@@ -159,6 +161,13 @@ enum ConfigCommand {
     Check,
 }
 
+#[derive(Debug, clap::Args)]
+struct RebuildArgs {
+    /// Date of the published issue to rebuild.
+    #[arg(long, value_name = "YYYY-MM-DD")]
+    date: jiff::civil::Date,
+}
+
 #[derive(Debug, clap::Args)]
 struct GenerateArgs {
     /// Issue date in the configured timezone (defaults to today).
@@ -382,6 +391,17 @@ async fn main() -> Result<()> {
             let outcome = pipeline::generate(&config, &db, &GenerateOptions::from(&args)).await?;
             print_outcome(&outcome);
         }
+        Command::Rebuild(args) => {
+            // No migration: this only re-renders what an existing schema holds.
+            let db = Db::open(&config.database_path).await?;
+            let published = pipeline::rebuild(&config, &db, args.date).await?;
+            for artifact in &published.epubs {
+                println!("{:?}: {}", artifact.edition, artifact.path.display());
+            }
+            if let Some(xtc) = &published.xtc {
+                println!("XTC: {}", xtc.display());
+            }
+        }
         Command::Serve => {
             let db = Db::open_and_migrate(&config.database_path).await?;
             let config_path = Config::resolve_path(cli.config.as_deref());
@@ -451,6 +471,14 @@ async fn main() -> Result<()> {
                     }
                     .description()
                 );
+                eprintln!(
+                    "  {:<20} {}",
+                    "rebuild-YYYY-MM-DD",
+                    jobs::Job::Rebuild {
+                        date: jiff::civil::Date::default()
+                    }
+                    .description()
+                );
                 std::process::exit(2);
             };
             let db = Db::open_and_migrate(&config.database_path).await?;
@@ -461,12 +489,13 @@ async fn main() -> Result<()> {
 }
 
 /// The commands that write the database and provider budgets and so hold the
-/// run lock (§5): `generate`, `profile rebuild`, `features backfill`,
+/// run lock (§5): `generate`, `rebuild`, `profile rebuild`, `features backfill`,
 /// `backfill-social`, `interests backfill`, and a `job run` of any of them.
 /// Everything else is read-only or its own writer.
 fn lock_holder(command: &Command) -> Option<&'static str> {
     match command {
         Command::Generate(_) => Some("generate"),
+        Command::Rebuild(_) => Some("rebuild"),
         // Writes the same tables the discovery stage of a run writes.
         Command::Feeds(FeedsCommand::Discover(_)) => Some("feeds discover"),
         Command::Profile(ProfileCommand::Rebuild) => Some("profile rebuild"),
@@ -1161,6 +1190,21 @@ async fn run_job(config: &Config, db: &Db, job: &jobs::Job) -> Result<(String, O
         jobs::Job::Generate { date } => {
             generate_job(config, db, date.map(|date| date.to_string()), false).await
         }
+        jobs::Job::Rebuild { date } => {
+            let published = pipeline::rebuild(config, db, *date).await?;
+            let xtc = if published.xtc.is_some() {
+                " and the XTC"
+            } else {
+                ""
+            };
+            Ok((
+                format!(
+                    "rebuilt the {date} issue: {} EPUBs{xtc}",
+                    published.epubs.len()
+                ),
+                None,
+            ))
+        }
         jobs::Job::DryRun => generate_job(config, db, None, true).await,
         jobs::Job::ProfileRebuild => Ok((cmd_profile_rebuild(config, db).await?, None)),
         jobs::Job::FeaturesBackfill => {

src/pipeline.rs

@@ -1095,6 +1095,51 @@ async fn persist_articles(db: &Db, articles: &mut [Article]) -> Result<()> {
     Ok(())
 }
 
+/// Rebuild and republish a published issue's EPUBs (and XTC) from its stored
+/// snapshot, for when rendering changed after the issue went out.
+///
+/// The content is exactly the issue's: the `issues.issue_json` snapshot with
+/// each article's body restored from its row (the snapshot drops bodies).
+/// Unlike the web reader it does not refresh anything else from the live rows,
+/// so social lines and metadata stay as published. Nothing is curated or
+/// fetched except the images, which are downloaded again as in a run.
+pub async fn rebuild(config: &Config, db: &Db, date: Date) -> Result<Published> {
+    let row = db
+        .issue_by_date(date)
+        .await?
+        .with_context(|| format!("no issue for {date}"))?;
+    let raw = row
+        .issue_json
+        .with_context(|| format!("the {date} issue predates issue snapshots"))?;
+    let mut issue: Issue = serde_json::from_str(&raw).context("decoding issues.issue_json")?;
+    let ids: Vec<ArticleId> = issue.lineup.picks.iter().map(|p| p.article.id).collect();
+    let mut articles = db.get_articles(&ids).await?;
+    for pick in &mut issue.lineup.picks {
+        let article = articles
+            .remove(&pick.article.id)
+            .with_context(|| format!("article {} is gone", pick.article.id))?;
+        pick.article.content_html = article.content_html;
+    }
+
+    let (artifacts, _) = epub::build_all(&issue, config, &config.out_dir)
+        .await
+        .context("building the EPUB editions")?;
+    let x4 = artifacts.iter().find(|a| a.edition == Edition::X4);
+    let xtc = match x4 {
+        Some(artifact) if config.xtc.enabled => {
+            Some(epub::x4::convert(&config.xtc, &artifact.path, &config.out_dir).await?)
+        }
+        _ => None,
+    };
+    let published = publish::publish_issue(config, &issue, &artifacts, xtc.as_deref())
+        .await
+        .context("publishing the issue")?;
+    record_issue(db, &issue, &published)
+        .await
+        .context("recording the issue")?;
+    Ok(published)
+}
+
 /// Write the `issues` row and replace `issue_articles` for the date (notes §12).
 async fn record_issue(db: &Db, issue: &Issue, published: &Published) -> Result<()> {
     let path_for = |edition: Edition| {
@@ -1346,6 +1391,91 @@ fn elapsed_ms(since: Timestamp) -> i64 {
 mod tests {
     use super::*;
 
+    /// Read one entry of a zip archive as text.
+    fn zip_entry(path: &std::path::Path, name: &str) -> String {
+        use std::io::Read;
+        let mut archive = zip::ZipArchive::new(std::fs::File::open(path).unwrap()).unwrap();
+        let mut text = String::new();
+        archive
+            .by_name(name)
+            .unwrap()
+            .read_to_string(&mut text)
+            .unwrap();
+        text
+    }
+
+    #[tokio::test]
+    async fn rebuild_republishes_from_the_snapshot_without_touching_it() {
+        let dir = tempfile::tempdir().unwrap();
+        let db = Db::open_and_migrate(&dir.path().join("db.sqlite"))
+            .await
+            .unwrap();
+        let mut issue = crate::epub::fixtures::issue();
+        for pick in &mut issue.lineup.picks {
+            // No images: the rebuild must not need the network here.
+            pick.article.content_html =
+                "<p>Before.</p><pre data-lang=\"rust\"><code>fn main() {}</code></pre>".into();
+            pick.article.image_count = 0;
+            let article = &pick.article;
+            db.upsert_entry(&crate::types::Entry {
+                id: article.best_entry_id,
+                feed_id: article.feed_id,
+                feed_title: Some(article.feed_title.clone()),
+                category: article.category.clone(),
+                title: article.title.clone(),
+                url: article.url.clone(),
+                canonical_url: Some(article.canonical_url.clone()),
+                author: article.author.clone(),
+                published_at: article.published_at,
+                comments_url: article.comments_url.clone(),
+                raw_content: article.content_html.clone(),
+                fetched_at: article.first_seen,
+            })
+            .await
+            .unwrap();
+            pick.article.id = db.upsert_article(article).await.unwrap();
+        }
+        let mut snapshot = issue.clone();
+        for pick in &mut snapshot.lineup.picks {
+            pick.article.content_html.clear();
+        }
+        let issue_json = serde_json::to_string(&snapshot).unwrap();
+        db.upsert_issue(
+            issue.meta.date,
+            issue.meta.issue_number,
+            issue.meta.generated_at,
+            None,
+            None,
+            None,
+            Some(&issue.editorial.front_page_html),
+            None,
+            Some(&issue_json),
+        )
+        .await
+        .unwrap();
+
+        let mut config = Config {
+            out_dir: dir.path().join("out"),
+            ..Config::default()
+        };
+        config.publish.epub_dir = dir.path().join("epubs");
+        config.publish.xtc_dir = dir.path().join("xtc");
+        config.xtc.enabled = false;
+        let published = rebuild(&config, &db, issue.meta.date).await.unwrap();
+
+        assert_eq!(published.epubs.len(), 2);
+        let row = db.issue_by_date(issue.meta.date).await.unwrap().unwrap();
+        assert_eq!(row.issue_json.as_deref(), Some(issue_json.as_str()));
+        let standard = &published.epubs[0];
+        assert_eq!(
+            row.epub_path.as_deref(),
+            Some(standard.path.to_str().unwrap())
+        );
+        let chapter = zip_entry(&standard.path, "OEBPS/art-1001.xhtml");
+        assert!(chapter.contains("<p>Before.</p>"), "body restored");
+        assert!(chapter.contains("<span class=\"hl-keyword\">fn</span>"));
+    }
+
     #[test]
     fn display_date_matches_the_masthead_format() {
         let date: Date = "2026-08-15".parse().unwrap();