diff --git a/crates/trodden-store/src/lib.rs b/crates/trodden-store/src/lib.rs
index e1d8b79..2098040 100644
--- a/crates/trodden-store/src/lib.rs
+++ b/crates/trodden-store/src/lib.rs
@@ -11,6 +11,7 @@ use std::{
 };
 
 use anyhow::{Context, Result, bail};
+use jiff::Timestamp;
 use rusqlite::{Connection, ErrorCode, OpenFlags, OptionalExtension, params};
 
 pub use ingest::{ExtractionRecord, Progress};
@@ -125,6 +126,15 @@ impl Store {
         self.set_setting("verify_reminder", if on { "1" } else { "0" })
     }
 
+    pub fn forgotten_before(&self) -> Result<Option<Timestamp>> {
+        self.setting("forgotten_before")?
+            .map(|at| {
+                at.parse()
+                    .context("parse the time everything was forgotten")
+            })
+            .transpose()
+    }
+
     pub fn embedding_scheme(&self) -> Result<Option<String>> {
         self.setting("embedding_scheme")
     }
diff --git a/crates/trodden-store/src/procedures.rs b/crates/trodden-store/src/procedures.rs
index 1c43e91..25327a3 100644
--- a/crates/trodden-store/src/procedures.rs
+++ b/crates/trodden-store/src/procedures.rs
@@ -686,6 +686,12 @@ impl Store {
         if matches!(target, Forget::All) {
             tx.execute_batch("DELETE FROM extractions; DELETE FROM sessions; DELETE FROM repos;")
                 .context("delete ingest history")?;
+            tx.execute(
+                "INSERT INTO settings (key, value) VALUES ('forgotten_before', ?1)
+                 ON CONFLICT (key) DO UPDATE SET value = excluded.value",
+                [Timestamp::now().to_string()],
+            )
+            .context("remember when everything was forgotten")?;
         }
         tx.commit().context("commit forgetting")?;
         Ok(deleted)
@@ -1071,6 +1077,26 @@ mod tests {
         );
     }
 
+    #[test]
+    fn forgetting_everything_remembers_when() {
+        let mut store = Store::open_in_memory().expect("store opens");
+        assert_eq!(store.forgotten_before().expect("setting reads"), None);
+        let before = Timestamp::now();
+
+        store.forget(Forget::All).expect("forgotten");
+
+        let forgotten = store
+            .forgotten_before()
+            .expect("setting reads")
+            .expect("the forget time is recorded");
+        assert!(before <= forgotten && forgotten <= Timestamp::now());
+        store.forget(Forget::Repo(REPO)).expect("forgotten again");
+        assert_eq!(
+            store.forgotten_before().expect("setting reads"),
+            Some(forgotten)
+        );
+    }
+
     #[test]
     fn relearning_a_quarantined_procedure_keeps_it_quarantined() {
         for (check, expected) in [
diff --git a/crates/trodden/src/ingest.rs b/crates/trodden/src/ingest.rs
index 08ed74b..2c61430 100644
--- a/crates/trodden/src/ingest.rs
+++ b/crates/trodden/src/ingest.rs
@@ -386,11 +386,16 @@ impl Ingest {
         };
         let mut extracted_through = already;
         let mut tasks = Vec::new();
+        let forgotten = self.store.forgotten_before()?;
+        let done = |seq: u32, at: Timestamp| {
+            already.is_some_and(|through| seq <= through)
+                || forgotten.is_some_and(|forgot| at <= forgot)
+        };
 
         let checks = ProjectChecks::discover(&workspace.root)
             .redacted(|command| self.redactor.redact(command).into_owned());
         for extraction in Extractor::new(checks).extract(&trace, &workspace.repo, ended) {
-            if already.is_some_and(|done| extraction.last_seq <= done) {
+            if done(extraction.last_seq, extraction.ended_at) {
                 continue;
             }
             tasks.push(TaskSpan {
@@ -398,7 +403,7 @@ impl Ingest {
                 last_seq: extraction.last_seq,
                 outcome: extraction.outcome,
             });
-            if already.is_some_and(|done| extraction.first_seq <= done) {
+            if done(extraction.first_seq, extraction.started_at) {
                 continue;
             }
             report.tasks += 1;
@@ -552,7 +557,7 @@ impl Ingest {
 #[cfg(test)]
 mod tests {
     use serde_json::{Value, json};
-    use trodden_store::{Cue, Injection};
+    use trodden_store::{Cue, Forget, Injection};
 
     use super::*;
 
@@ -806,6 +811,21 @@ mod tests {
             ]
         }
 
+        fn tomorrow(lines: &[Value]) -> Vec<Value> {
+            let tomorrow = Timestamp::now()
+                .checked_add(jiff::SignedDuration::from_hours(24))
+                .expect("tomorrow is representable")
+                .strftime("%Y-%m-%d")
+                .to_string();
+            lines
+                .iter()
+                .map(|line| {
+                    serde_json::from_str(&line.to_string().replace("2026-10-01", &tomorrow))
+                        .expect("moved line is JSON")
+                })
+                .collect()
+        }
+
         fn inject(ingest: &Ingest, minute: u32) {
             let row = ingest
                 .store
@@ -949,6 +969,57 @@ mod tests {
         );
     }
 
+    #[test]
+    fn live_sessions_do_not_relearn_what_was_forgotten() {
+        let scratch = Scratch::new("forget-live");
+        let mut ingest = scratch.ingest();
+        scratch.append(&Scratch::task(
+            0,
+            "Page 2 in src/paginate.js repeats the last product from page 1",
+            "src/paginate.js",
+        ));
+        scratch.append(&Scratch::task(
+            5,
+            "Checkout in src/checkout.js charges shipping twice",
+            "src/checkout.js",
+        ));
+        let learned = ingest
+            .transcript(Harness::ClaudeCode, &scratch.transcript, false)
+            .expect("ingest before forgetting");
+        assert_eq!((learned.tasks, learned.created), (1, 1));
+
+        ingest
+            .store
+            .forget(Forget::All)
+            .expect("everything is forgotten");
+        scratch.append(&Scratch::tomorrow(&Scratch::task(
+            10,
+            "The cart total in src/cart.js ignores the discount code",
+            "src/cart.js",
+        )));
+        scratch.append(&Scratch::tomorrow(&Scratch::task(
+            15,
+            "The search in src/search.js drops accented names",
+            "src/search.js",
+        )));
+        let next = ingest
+            .transcript(Harness::ClaudeCode, &scratch.transcript, false)
+            .expect("ingest after forgetting");
+
+        assert_eq!((next.tasks, next.created), (1, 1));
+        let titles: Vec<_> = ingest
+            .store
+            .list(None, true)
+            .expect("procedures list")
+            .into_iter()
+            .map(|row| row.procedure.title)
+            .collect();
+        assert_eq!(
+            titles,
+            ["The cart total in src/cart.js ignores the discount code"]
+        );
+    }
+
     #[test]
     fn sessions_spanning_a_pause_learn_only_what_followed_it() {
         let scratch = Scratch::new("spanning-pause");