diff --git a/crates/oa-core/src/language/analysis_source/update.rs b/crates/oa-core/src/language/analysis_source/update.rs
index bab14f41..4c02c91f 100644
--- a/crates/oa-core/src/language/analysis_source/update.rs
+++ b/crates/oa-core/src/language/analysis_source/update.rs
@@ -25,6 +25,17 @@ impl<'i, 's> Plan<'i, 's> {
         renames: &BTreeMap<Target, String>,
         budget: &Budget,
     ) -> Result<Self, Error> {
+        let plan = Self::prepare(index, renames, budget)?;
+        plan.validate(index.sources(), budget)?;
+        plan.output_lengths(index.sources(), budget)?;
+        Ok(plan)
+    }
+
+    fn validate_names(
+        index: &Index<'_>,
+        renames: &BTreeMap<Target, String>,
+        budget: &Budget,
+    ) -> Result<(), Error> {
         budget.active()?;
         budget.lowering_entries(renames.len(), Span::default())?;
         let mut bytes = 0usize;
@@ -61,6 +72,16 @@ impl<'i, 's> Plan<'i, 's> {
                 ));
             }
         }
+        Ok(())
+    }
+
+    fn prepare(
+        index: &'i Index<'s>,
+        renames: &BTreeMap<Target, String>,
+        budget: &Budget,
+    ) -> Result<Self, Error> {
+        // Validate record/name storage before copying any owned final names.
+        Self::validate_names(index, renames, budget)?;
         let mut edits = Vec::new();
         for (key, location) in index.occurrences() {
             if renames
@@ -81,26 +102,20 @@ impl<'i, 's> Plan<'i, 's> {
                 edit.location.span.end,
             )
         });
-        let plan = Self {
+        Ok(Self {
             index,
             names: renames.clone(),
             edits,
-        };
-        plan.validate(index.sources(), budget)?;
-        Ok(plan)
+        })
     }
 
     pub fn edit_count(&self) -> usize {
         self.edits.len()
     }
 
-    /// Recheck all files, all edit ownership and all final sizes before any
-    /// output String is allocated. A changed unrelated file is stale too.
-    fn validate(
-        &self,
-        current: &BTreeMap<usize, String>,
-        budget: &Budget,
-    ) -> Result<BTreeMap<usize, usize>, Error> {
+    /// Recheck the complete original witness and complete rename intent.
+    /// A changed unrelated file is stale too. This does not construct output.
+    fn validate(&self, current: &BTreeMap<usize, String>, budget: &Budget) -> Result<(), Error> {
         budget.active()?;
         if current != self.index.sources() {
             return Err(error(
@@ -108,12 +123,9 @@ impl<'i, 's> Plan<'i, 's> {
                 "Source index is stale: original file set or bytes changed.",
             ));
         }
+        Self::validate_names(self.index, &self.names, budget)?;
         budget.lowering_entries(current.len(), Span::default())?;
         budget.lowering_occurrences(self.edits.len(), Span::default())?;
-        let mut lengths: BTreeMap<_, _> = current
-            .iter()
-            .map(|(&file, source)| (file, source.len()))
-            .collect();
         let mut previous: Option<Location> = None;
         let mut seen = BTreeSet::new();
         for edit in &self.edits {
@@ -130,8 +142,7 @@ impl<'i, 's> Plan<'i, 's> {
             {
                 return Err(error(at.span, "Stale original token spelling."));
             }
-            let replacement = self
-                .names
+            self.names
                 .get(&edit.key.target)
                 .ok_or_else(|| error(at.span, "Edit has no final target name."))?;
             if previous.is_some_and(|prior| {
@@ -140,13 +151,6 @@ impl<'i, 's> Plan<'i, 's> {
                 return Err(error(at.span, "Overlapping or unordered source edits."));
             }
             previous = Some(at);
-            let length = lengths
-                .get_mut(&at.file)
-                .ok_or_else(|| error(at.span, "Unknown edit file."))?;
-            *length = length
-                .checked_sub(old.len())
-                .and_then(|size| size.checked_add(replacement.len()))
-                .ok_or_else(|| error(at.span, "Updated source size overflow."))?;
         }
         for (key, at) in self.index.occurrences() {
             let required = self
@@ -160,6 +164,28 @@ impl<'i, 's> Plan<'i, 's> {
                 ));
             }
         }
+        Ok(())
+    }
+
+    /// Standalone output preflight, after ownership validation. Composition
+    /// defers this hypothetical typed-only size to its future combined emitter.
+    fn output_lengths(
+        &self,
+        current: &BTreeMap<usize, String>,
+        budget: &Budget,
+    ) -> Result<BTreeMap<usize, usize>, Error> {
+        let mut lengths: BTreeMap<_, _> = current
+            .iter()
+            .map(|(&file, source)| (file, source.len()))
+            .collect();
+        for edit in &self.edits {
+            let at = edit.location;
+            let length = lengths.get_mut(&at.file).expect("validated edit file");
+            *length = length
+                .checked_sub(at.span.end - at.span.start)
+                .and_then(|size| size.checked_add(self.names[&edit.key.target].len()))
+                .ok_or_else(|| error(at.span, "Updated source size overflow."))?;
+        }
         let mut total = 0usize;
         for length in lengths.values() {
             total = total
@@ -175,7 +201,8 @@ impl<'i, 's> Plan<'i, 's> {
         current: &BTreeMap<usize, String>,
         budget: &Budget,
     ) -> Result<BTreeMap<usize, String>, Error> {
-        let lengths = self.validate(current, budget)?;
+        self.validate(current, budget)?;
+        let lengths = self.output_lengths(current, budget)?;
         let mut result = BTreeMap::new();
         let mut edits = self.edits.iter().peekable();
         for (&file, source) in current {
@@ -194,5 +221,96 @@ impl<'i, 's> Plan<'i, 's> {
     }
 }
 
+/// Private typed-only composition planning. The caller must supply its inherited
+/// parse Budget; this type keeps that same immutable budget through export.
+/// It does not establish the future complete bundle/file-table/parse-session
+/// witness. In particular, an Index currently does not store its parse profile.
+pub(super) struct Composition<'b, 'i, 's> {
+    plan: Plan<'i, 's>,
+    budget: &'b Budget,
+}
+impl std::fmt::Debug for Composition<'_, '_, '_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Composition")
+            .field("plan", &self.plan)
+            .finish_non_exhaustive()
+    }
+}
+impl<'b, 'i, 's> Composition<'b, 'i, 's> {
+    pub fn renames(
+        index: &'i Index<'s>,
+        renames: &BTreeMap<Target, String>,
+        inherited: &'b Budget,
+    ) -> Result<Self, Error> {
+        let plan = Plan::prepare(index, renames, inherited)?;
+        plan.validate(index.sources(), inherited)?;
+        Ok(Self {
+            plan,
+            budget: inherited,
+        })
+    }
+
+    /// Export the entire validated plan against exact original numeric file keys
+    /// and bytes. There is no output allocation, application or subset-accept API.
+    /// A future collector must check this actual index witness and the complete
+    /// combined output bounds before applying either producer's edits once.
+    pub fn original_edits(
+        &self,
+        current: &BTreeMap<usize, String>,
+    ) -> Result<OriginalEdits<'_, 'i, 's>, Error> {
+        self.plan.validate(current, self.budget)?;
+        Ok(OriginalEdits { plan: &self.plan })
+    }
+}
+
+#[derive(Debug)]
+pub(super) struct OriginalEdits<'p, 'i, 's> {
+    plan: &'p Plan<'i, 's>,
+}
+impl<'s> OriginalEdits<'_, '_, 's> {
+    pub fn index(&self) -> &Index<'s> {
+        self.plan.index
+    }
+    pub fn len(&self) -> usize {
+        self.plan.edits.len()
+    }
+    pub fn is_empty(&self) -> bool {
+        self.plan.edits.is_empty()
+    }
+    pub fn iter(&self) -> impl ExactSizeIterator<Item = OriginalEdit<'_>> {
+        self.plan.edits.iter().map(|edit| OriginalEdit {
+            key: &edit.key,
+            location: edit.location,
+            original: &self.plan.index.sources()[&edit.location.file]
+                [edit.location.span.start..edit.location.span.end],
+            replacement: &self.plan.names[&edit.key.target],
+        })
+    }
+}
+
+/// A borrowed inspection record, never independent edit authority. Only an
+/// intact OriginalEdits batch can carry this producer's complete rename intent.
+#[derive(Debug)]
+pub(super) struct OriginalEdit<'p> {
+    key: &'p OccurrenceKey,
+    location: Location,
+    original: &'p str,
+    replacement: &'p str,
+}
+impl OriginalEdit<'_> {
+    pub fn key(&self) -> &OccurrenceKey {
+        self.key
+    }
+    pub fn location(&self) -> Location {
+        self.location
+    }
+    pub fn original(&self) -> &str {
+        self.original
+    }
+    pub fn replacement(&self) -> &str {
+        self.replacement
+    }
+}
+
 #[cfg(test)]
 mod tests;
diff --git a/crates/oa-core/src/language/analysis_source/update/tests.rs b/crates/oa-core/src/language/analysis_source/update/tests.rs
index a9e9b4e5..2a956897 100644
--- a/crates/oa-core/src/language/analysis_source/update/tests.rs
+++ b/crates/oa-core/src/language/analysis_source/update/tests.rs
@@ -322,3 +322,390 @@ fn output_and_plan_limits_are_aggregate_and_do_not_reset_parse_work() {
     limits.entries = 0;
     assert!(Plan::renames(&index, &rename_map(), &Budget::new(limits).unwrap()).is_err());
 }
+
+#[test]
+fn composition_exports_complete_borrowed_swap_witnesses_and_empty_noops() {
+    use super::super::index::TokenRole;
+    use super::super::lower::{Child, Field, Role};
+    type Key = (Id, Option<Field>, Option<Vec<Child>>, TokenRole, Target);
+    type Row = (Location, String, String, Key);
+
+    let sources = sources();
+    let mut work = budget();
+    let (index, _) = Index::parse(&skeleton(), &sources, &mut work).unwrap();
+    let usage = work.usage;
+    let numeric = work.numeric_units();
+    let composition = Composition::renames(&index, &rename_map(), &work).unwrap();
+    assert!(std::ptr::eq(composition.budget, &work));
+    // A byte-identical snapshot is valid; records still borrow the actual index.
+    let batch = composition.original_edits(&sources.clone()).unwrap();
+    assert!(std::ptr::eq(batch.index(), &index));
+    assert_eq!(batch.len(), 13);
+    assert!(!batch.is_empty());
+    assert_eq!(batch.iter().len(), 13);
+
+    // Independently authored occurrence identities and full source contexts.
+    // No index offset/path or generated output defines this oracle.
+    let mut expected: Vec<Row> = Vec::new();
+    let mut add = |file, context: &str, prefix: &str, old: &str, new: &str, key: Key| {
+        let start = sources[&file].find(context).unwrap() + prefix.len();
+        assert_eq!(&sources[&file][start..start + old.len()], old);
+        expected.push((
+            Location {
+                file,
+                span: Span {
+                    start,
+                    end: start + old.len(),
+                },
+            },
+            old.into(),
+            new.into(),
+            key,
+        ));
+    };
+    for (id, old, new, context) in [
+        (0x100, "f", "g", "calculation f "),
+        (0x200, "g", "f", "calculation g "),
+    ] {
+        add(
+            11,
+            context,
+            "calculation ",
+            old,
+            new,
+            (
+                Id::from_u128(id),
+                None,
+                None,
+                TokenRole::Declaration,
+                global(id),
+            ),
+        );
+    }
+    for (id, old, new, context, edge, prefix) in [
+        (0x200, "a", "b", "input a id", Child::Left, "body $"),
+        (0x201, "b", "a", "input b id", Child::Right, "body $a + $"),
+    ] {
+        let target = parameter(0x100, id);
+        add(
+            11,
+            context,
+            "input ",
+            old,
+            new,
+            (
+                Id::from_u128(0x100),
+                Some(Field::Input(a::ParameterId(Id::from_u128(id)))),
+                None,
+                TokenRole::Use(Role::ParameterDeclaration),
+                target,
+            ),
+        );
+        add(
+            11,
+            "body $a + $b;",
+            prefix,
+            old,
+            new,
+            (
+                Id::from_u128(0x100),
+                Some(Field::Body),
+                Some(vec![edge]),
+                TokenRole::Use(Role::ParameterUse),
+                target,
+            ),
+        );
+    }
+    for (context, path) in [
+        ("@f(b: 2, a: 1)", vec![Child::Left, Child::Left]),
+        ("@f(a: 3, b: 4)", vec![Child::Left, Child::Right]),
+    ] {
+        add(
+            23,
+            context,
+            "@",
+            "f",
+            "g",
+            (
+                Id::from_u128(0x300),
+                Some(Field::Body),
+                Some(path.clone()),
+                TokenRole::Use(Role::CallTarget),
+                global(0x100),
+            ),
+        );
+        for (id, old, new) in [(0x200, "a", "b"), (0x201, "b", "a")] {
+            let offset = context.find(&format!("{old}:")).unwrap();
+            add(
+                23,
+                context,
+                &context[..offset],
+                old,
+                new,
+                (
+                    Id::from_u128(0x300),
+                    Some(Field::Body),
+                    Some(path.clone()),
+                    TokenRole::Use(Role::ArgumentLabel),
+                    parameter(0x100, id),
+                ),
+            );
+        }
+    }
+    add(
+        23,
+        "@g(a: 5, b: 6)",
+        "@",
+        "g",
+        "f",
+        (
+            Id::from_u128(0x300),
+            Some(Field::Body),
+            Some(vec![Child::Right]),
+            TokenRole::Use(Role::CallTarget),
+            global(0x200),
+        ),
+    );
+    expected.sort_by_key(|row| (row.0.file, row.0.span.start, row.0.span.end));
+    let actual: Vec<Row> = batch
+        .iter()
+        .map(|edit| {
+            let key = edit.key();
+            (
+                edit.location(),
+                edit.original().into(),
+                edit.replacement().into(),
+                (
+                    key.owner,
+                    key.field,
+                    key.path.as_ref().map(|path| path.edges()),
+                    key.role,
+                    key.target,
+                ),
+            )
+        })
+        .collect();
+    assert_eq!(actual, expected);
+
+    let noop = Composition::renames(
+        &index,
+        &BTreeMap::from([
+            (global(0x100), "f".into()),
+            (parameter(0x200, 0x200), "a".into()),
+        ]),
+        &work,
+    )
+    .unwrap();
+    let empty = noop.original_edits(&sources).unwrap();
+    assert!(empty.is_empty());
+    assert_eq!(empty.len(), 0);
+    assert_eq!(empty.iter().count(), 0);
+    assert_eq!(work.usage, usage);
+    assert_eq!(work.numeric_units(), numeric);
+}
+
+#[test]
+fn composition_rejects_stale_or_damaged_complete_batches_before_export() {
+    let mut sources = sources();
+    sources.insert(99, "// unrelated 雪\r\n".into());
+    let original = sources.clone();
+    let mut work = budget();
+    let (index, _) = Index::parse(&skeleton(), &sources, &mut work).unwrap();
+    for damage in 0..10 {
+        let mut current = sources.clone();
+        let mut composition = Composition::renames(&index, &rename_map(), &work).unwrap();
+        match damage {
+            0 => current.get_mut(&99).unwrap().push_str("changed"),
+            1 => {
+                current.remove(&23);
+            }
+            2 => {
+                current.insert(101, String::new());
+            }
+            3 => composition.plan.edits[0].location.span.start += 1,
+            4 => composition
+                .plan
+                .edits
+                .insert(1, composition.plan.edits[0].clone()),
+            5 => {
+                composition.plan.edits.pop();
+            }
+            6 => composition.plan.edits.swap(0, 1),
+            7 => {
+                composition
+                    .plan
+                    .names
+                    .insert(global(0x100), "bad name".into());
+            }
+            8 => {
+                composition.plan.names.insert(global(0x100), "f".into());
+            }
+            _ => {
+                composition.plan.names.insert(global(999), "missing".into());
+            }
+        }
+        let before = current.clone();
+        assert!(
+            composition.original_edits(&current).is_err(),
+            "damage {damage}"
+        );
+        assert_eq!(current, before);
+    }
+    assert_eq!(sources, original);
+    let failure = work.frame(257, Span::default()).unwrap_err();
+    assert_eq!(
+        Composition::renames(&index, &rename_map(), &work).unwrap_err(),
+        failure
+    );
+}
+
+#[test]
+fn composition_defers_only_typed_output_size_with_independent_shrink_arithmetic() {
+    let sources = sources();
+    let cap = sources.values().map(String::len).sum();
+    let mut limits = Limits::source8(ParseLimits::UNLIMITED);
+    limits.bytes = cap;
+    let mut work = Budget::new(limits).unwrap();
+    let (index, _) = Index::parse(&skeleton(), &sources, &mut work).unwrap();
+    assert_eq!(work.usage.bytes, cap);
+    let usage = work.usage;
+    let numeric = work.numeric_units();
+    let names = BTreeMap::from([(global(0x100), "ff".into())]);
+    assert_eq!(
+        Plan::renames(&index, &names, &work).unwrap_err().message,
+        "Source8 index/output byte limit exceeded."
+    );
+    let composition = Composition::renames(&index, &names, &work).unwrap();
+    let batch = composition.original_edits(&sources).unwrap();
+    assert_eq!(batch.len(), 3); // declaration and two distinct call targets
+    let growth: usize = batch
+        .iter()
+        .map(|edit| edit.replacement().len() - edit.original().len())
+        .sum();
+    assert_eq!(growth, 3);
+    assert_eq!(
+        composition.plan.apply(&sources, &work).unwrap_err().message,
+        "Source8 index/output byte limit exceeded."
+    );
+
+    // Independent future ordinary/scalar producer witness on untouched display
+    // name bytes. This is size/offset arithmetic only: this typed-only harness
+    // has no ordinary collector, mixed ownership proof or accepted output.
+    let start = DEFINITIONS.find("\"f a b\"").unwrap() + 1;
+    let shrink = Location {
+        file: 11,
+        span: Span {
+            start,
+            end: start + "f a b".len(),
+        },
+    };
+    assert_eq!(
+        &sources[&shrink.file][shrink.span.start..shrink.span.end],
+        "f a b"
+    );
+    for edit in batch.iter() {
+        let at = edit.location();
+        assert!(
+            at.file != shrink.file
+                || at.span.end <= shrink.span.start
+                || shrink.span.end <= at.span.start
+        );
+    }
+    let original_len = shrink.span.end - shrink.span.start;
+    assert_eq!(cap + growth - original_len + "fa".len(), cap);
+    assert_eq!(cap + growth - original_len + "fab".len(), cap + 1);
+    assert_eq!(work.usage, usage);
+    assert_eq!(work.numeric_units(), numeric);
+}
+
+#[test]
+fn composition_keeps_name_storage_and_rename_record_limits_before_allocation() {
+    let sources = sources();
+    let cap = sources.values().map(String::len).sum();
+    let mut limits = Limits::source8(ParseLimits::UNLIMITED);
+    limits.bytes = cap;
+    let mut work = Budget::new(limits).unwrap();
+    let (index, _) = Index::parse(&skeleton(), &sources, &mut work).unwrap();
+    let exact = BTreeMap::from([(global(0x100), "x".repeat(cap))]);
+    assert_eq!(
+        Composition::renames(&index, &exact, &work)
+            .unwrap()
+            .original_edits(&sources)
+            .unwrap()
+            .len(),
+        3
+    );
+    let over = BTreeMap::from([(global(0x100), "x".repeat(cap + 1))]);
+    assert_eq!(
+        Composition::renames(&index, &over, &work)
+            .unwrap_err()
+            .message,
+        "Source8 index/output byte limit exceeded."
+    );
+    for invalid in [
+        BTreeMap::from([(global(999), "unknown".into())]),
+        BTreeMap::from([(global(0x100), "bad name".into())]),
+        BTreeMap::from([(global(0x100), "g".into())]),
+        BTreeMap::from([(parameter(0x100, 0x200), "b".into())]),
+    ] {
+        assert!(Composition::renames(&index, &invalid, &work).is_err());
+    }
+
+    // A typed-empty fixture isolates the rename-map record bound without
+    // syntax entry usage masking it. No ordinary edits are authorized here.
+    let ordinary = skeleton();
+    let count = ordinary.identities().len();
+    let files = BTreeMap::from([(1, "// empty typed unit\n".into())]);
+    let mut limits = Limits::source8(ParseLimits::UNLIMITED);
+    limits.entries = count;
+    limits.references = 0;
+    let mut inherited = Budget::new(limits).unwrap();
+    let (index, _) = Index::parse(&ordinary, &files, &mut inherited).unwrap();
+    let mut names: BTreeMap<_, _> = index
+        .names()
+        .keys()
+        .enumerate()
+        .map(|(i, target)| (*target, format!("renamed_{i}")))
+        .collect();
+    assert_eq!(names.len(), count);
+    assert!(
+        Composition::renames(&index, &names, &inherited)
+            .unwrap()
+            .original_edits(&files)
+            .unwrap()
+            .is_empty()
+    );
+    names.insert(global(999), "additional".into());
+    assert_eq!(
+        Composition::renames(&index, &names, &inherited)
+            .unwrap_err()
+            .message,
+        "Source8 lowering entry limit exceeded."
+    );
+}
+
+#[test]
+fn composition_checks_edit_record_ceiling_before_duplicate_membership() {
+    let sources = sources();
+    let mut limits = Limits::source8(ParseLimits::UNLIMITED);
+    limits.entries = 128;
+    limits.references = 32;
+    let ceiling = limits.entries + limits.references;
+    let mut work = Budget::new(limits).unwrap();
+    let (index, _) = Index::parse(&skeleton(), &sources, &mut work).unwrap();
+    let mut composition = Composition::renames(&index, &rename_map(), &work).unwrap();
+    assert_eq!(composition.original_edits(&sources).unwrap().len(), 13);
+    let duplicate = composition.plan.edits[0].clone();
+    composition.plan.edits = vec![duplicate.clone(); ceiling];
+    // At the exact count bound validation proceeds to the independent ownership
+    // error. The damaged plan never becomes a successful/authoritative batch.
+    assert_eq!(
+        composition.original_edits(&sources).unwrap_err().message,
+        "Forged or duplicate edit occurrence."
+    );
+    composition.plan.edits.push(duplicate);
+    assert_eq!(
+        composition.original_edits(&sources).unwrap_err().message,
+        "Source8 lowering occurrence limit exceeded."
+    );
+}