diff --git a/regress/expected/age_upgrade.out b/regress/expected/age_upgrade.out
index edf8e6022..446e0eb76 100644
--- a/regress/expected/age_upgrade.out
+++ b/regress/expected/age_upgrade.out
@@ -27,16 +27,30 @@
 -- upgrade template.
 --
 -- Compared catalogs:
---   pg_proc     — functions, aggregates, procedures (name, args, properties)
+--   pg_proc     — functions, aggregates, procedures (name, args, properties
+--                 including probin/prosrc to catch C-symbol renames and
+--                 SQL-body changes)
 --   pg_class    — tables, views, sequences, indexes (name, kind)
 --   pg_type     — types (name, type category)
 --   pg_operator — operators (name, left/right types)
 --   pg_cast     — casts involving AGE types (source, target, context)
 --   pg_opclass  — operator classes (name, access method)
 --   pg_constraint — constraints (name, type, table, referenced table)
+--   pg_depend   — extension membership (every AGE-owned object must be
+--                 linked back to the extension via deptype='e'; catches
+--                 a missing ALTER EXTENSION age ADD ... in the template)
 --
 -- All comparison queries should return 0 rows.
 --
+-- Note on synthetic-initial install (step 10): the synthetic '*_initial'
+-- snapshot is built from a fixed historical commit, so its CREATE FUNCTION
+-- statements may reference C symbols that have since been removed from the
+-- current age.so. Step 10 disables check_function_bodies so that dlsym is
+-- deferred to call time; the immediately-following ALTER EXTENSION UPDATE
+-- (step 11) DROPs any such retired functions before any plan can call them.
+-- This lets developers cleanly remove deprecated C entry points without
+-- needing to keep error-raising stubs in age.so.
+--
 LOAD 'age';
 SET search_path TO ag_catalog;
 -- Step 1: Clean up any graphs left by prior tests (deterministic, no output).
@@ -56,15 +70,23 @@ BEGIN
 END
 $$;
 -- =====================================================================
--- FRESH INSTALL SNAPSHOTS (Steps 2-7)
+-- FRESH INSTALL SNAPSHOTS (Steps 2-7b)
 -- Capture the catalog state from the default CREATE EXTENSION install.
 -- =====================================================================
 -- Step 2: Snapshot functions (includes aggregates via prokind).
+-- probin/prosrc capture the binding to the implementation:
+--   * LANGUAGE c        : probin = '$libdir/age', prosrc = C symbol name
+--                         (a renamed/retargeted symbol shows up here)
+--   * LANGUAGE sql/plpgsql: probin = NULL, prosrc = function body text
+--                         (a body change in the upgrade template shows up here)
+--   * LANGUAGE internal : probin = NULL, prosrc = builtin name
 CREATE TEMP TABLE _fresh_funcs AS
 SELECT proname::text,
        pg_get_function_identity_arguments(oid) AS args,
        provolatile::text, proisstrict::text, prokind::text,
-       prorettype::regtype::text AS rettype, proretset::text
+       prorettype::regtype::text AS rettype, proretset::text,
+       COALESCE(probin, '')  AS probin,
+       COALESCE(prosrc, '')  AS prosrc
 FROM pg_proc
 WHERE pronamespace = 'ag_catalog'::regnamespace
 ORDER BY proname, args;
@@ -113,6 +135,57 @@ SELECT conname::text, contype::text,
 FROM pg_constraint
 WHERE connamespace = 'ag_catalog'::regnamespace
 ORDER BY conname;
+-- Step 7b: Snapshot extension membership (pg_depend deptype='e').
+-- Every object that CREATE EXTENSION owns has a row in pg_depend linking
+-- it to the extension. The upgrade template must produce the same set:
+-- if it CREATEs an object but forgets to ALTER EXTENSION ADD it, the
+-- catalog row exists (so funcs_match/rels_match would pass) but the
+-- pg_depend link is absent and pg_dump --extension would diverge.
+CREATE TEMP TABLE _fresh_extmembers AS
+SELECT
+    CASE d.classid
+        WHEN 'pg_proc'::regclass
+            THEN 'function: '   || d.objid::regprocedure::text
+        WHEN 'pg_type'::regclass
+            THEN 'type: '       || d.objid::regtype::text
+        WHEN 'pg_class'::regclass
+            THEN 'relation: '   || d.objid::regclass::text
+            || ' ('   || (SELECT relkind::text FROM pg_class WHERE oid = d.objid) || ')'
+        WHEN 'pg_operator'::regclass
+            THEN 'operator: '   || d.objid::regoperator::text
+        WHEN 'pg_cast'::regclass
+            THEN 'cast: '       || (SELECT castsource::regtype::text || ' -> ' || casttarget::regtype::text
+                                    FROM pg_cast WHERE oid = d.objid)
+        WHEN 'pg_opclass'::regclass
+            THEN 'opclass: '    || (SELECT opcname || ' (' || (SELECT amname FROM pg_am WHERE oid = opcmethod) || ')'
+                                    FROM pg_opclass WHERE oid = d.objid)
+        WHEN 'pg_constraint'::regclass
+            THEN 'constraint: ' || (SELECT conname || ' on ' || conrelid::regclass::text
+                                    FROM pg_constraint WHERE oid = d.objid)
+        WHEN 'pg_opfamily'::regclass
+            THEN 'opfamily: '   || (SELECT opfname || ' (' || (SELECT amname FROM pg_am WHERE oid = opfmethod) || ')'
+                                    FROM pg_opfamily WHERE oid = d.objid)
+        WHEN 'pg_amop'::regclass
+            THEN 'amop: '       || (SELECT (SELECT opfname FROM pg_opfamily WHERE oid = a.amopfamily)
+                                       || ' [strategy ' || a.amopstrategy || '] '
+                                       || a.amoplefttype::regtype::text  || ','
+                                       || a.amoprighttype::regtype::text || ' op '
+                                       || a.amopopr::regoperator::text
+                                    FROM pg_amop a WHERE a.oid = d.objid)
+        WHEN 'pg_amproc'::regclass
+            THEN 'amproc: '     || (SELECT (SELECT opfname FROM pg_opfamily WHERE oid = p.amprocfamily)
+                                       || ' [proc ' || p.amprocnum || '] '
+                                       || p.amproclefttype::regtype::text  || ','
+                                       || p.amprocrighttype::regtype::text || ' fn '
+                                       || p.amproc::regprocedure::text
+                                    FROM pg_amproc p WHERE p.oid = d.objid)
+        ELSE 'unhandled[' || d.classid::regclass::text || ']'
+    END AS member
+FROM pg_depend d
+WHERE d.deptype = 'e'
+  AND d.refclassid = 'pg_extension'::regclass
+  AND d.refobjid   = (SELECT oid FROM pg_extension WHERE extname = 'age')
+ORDER BY 1;
 -- Step 8: Drop AGE entirely.
 DROP EXTENSION age;
 -- Step 9: Verify we have an upgrade path available.
@@ -124,6 +197,19 @@ FROM pg_available_extension_versions WHERE name = 'age';
 (1 row)
 
 -- Step 10: Install AGE at the synthetic initial version.
+--
+-- Disable check_function_bodies for this CREATE only. The synthetic
+-- '*_initial' SQL is pulled from a fixed historical commit and may
+-- declare C functions whose symbols have since been removed from the
+-- current age.so. With check_function_bodies=on, PostgreSQL would dlsym
+-- each such symbol at CREATE FUNCTION time and abort. Deferring the
+-- symbol probe to call time is safe because step 11 (ALTER EXTENSION
+-- UPDATE) immediately runs the upgrade template, which DROPs any
+-- removed-in-HEAD functions before the test (or any user) can call them.
+-- The fresh CREATE EXTENSION at step 35 keeps the GUC at its default,
+-- so any inconsistency between HEAD's SQL and HEAD's age.so is still
+-- caught at install time on the production code path.
+SET check_function_bodies = off;
 DO $$
 DECLARE init_ver text;
 BEGIN
@@ -138,6 +224,7 @@ BEGIN
     EXECUTE format('CREATE EXTENSION age VERSION %L', init_ver);
 END;
 $$;
+RESET check_function_bodies;
 -- Step 11: Upgrade to the current (default) version via the stamped template.
 DO $$
 DECLARE curr_ver text;
@@ -160,15 +247,17 @@ FROM pg_available_extensions WHERE name = 'age';
 (1 row)
 
 -- =====================================================================
--- UPGRADED INSTALL SNAPSHOTS (Steps 13-18)
+-- UPGRADED INSTALL SNAPSHOTS (Steps 13-18b)
 -- Capture the catalog state after upgrade from initial to current.
 -- =====================================================================
--- Step 13: Snapshot functions.
+-- Step 13: Snapshot functions (probin/prosrc included; see step 2).
 CREATE TEMP TABLE _upgraded_funcs AS
 SELECT proname::text,
        pg_get_function_identity_arguments(oid) AS args,
        provolatile::text, proisstrict::text, prokind::text,
-       prorettype::regtype::text AS rettype, proretset::text
+       prorettype::regtype::text AS rettype, proretset::text,
+       COALESCE(probin, '')  AS probin,
+       COALESCE(prosrc, '')  AS prosrc
 FROM pg_proc
 WHERE pronamespace = 'ag_catalog'::regnamespace
 ORDER BY proname, args;
@@ -217,8 +306,54 @@ SELECT conname::text, contype::text,
 FROM pg_constraint
 WHERE connamespace = 'ag_catalog'::regnamespace
 ORDER BY conname;
+-- Step 18b: Snapshot extension membership after upgrade (see step 7b).
+CREATE TEMP TABLE _upgraded_extmembers AS
+SELECT
+    CASE d.classid
+        WHEN 'pg_proc'::regclass
+            THEN 'function: '   || d.objid::regprocedure::text
+        WHEN 'pg_type'::regclass
+            THEN 'type: '       || d.objid::regtype::text
+        WHEN 'pg_class'::regclass
+            THEN 'relation: '   || d.objid::regclass::text
+            || ' ('   || (SELECT relkind::text FROM pg_class WHERE oid = d.objid) || ')'
+        WHEN 'pg_operator'::regclass
+            THEN 'operator: '   || d.objid::regoperator::text
+        WHEN 'pg_cast'::regclass
+            THEN 'cast: '       || (SELECT castsource::regtype::text || ' -> ' || casttarget::regtype::text
+                                    FROM pg_cast WHERE oid = d.objid)
+        WHEN 'pg_opclass'::regclass
+            THEN 'opclass: '    || (SELECT opcname || ' (' || (SELECT amname FROM pg_am WHERE oid = opcmethod) || ')'
+                                    FROM pg_opclass WHERE oid = d.objid)
+        WHEN 'pg_constraint'::regclass
+            THEN 'constraint: ' || (SELECT conname || ' on ' || conrelid::regclass::text
+                                    FROM pg_constraint WHERE oid = d.objid)
+        WHEN 'pg_opfamily'::regclass
+            THEN 'opfamily: '   || (SELECT opfname || ' (' || (SELECT amname FROM pg_am WHERE oid = opfmethod) || ')'
+                                    FROM pg_opfamily WHERE oid = d.objid)
+        WHEN 'pg_amop'::regclass
+            THEN 'amop: '       || (SELECT (SELECT opfname FROM pg_opfamily WHERE oid = a.amopfamily)
+                                       || ' [strategy ' || a.amopstrategy || '] '
+                                       || a.amoplefttype::regtype::text  || ','
+                                       || a.amoprighttype::regtype::text || ' op '
+                                       || a.amopopr::regoperator::text
+                                    FROM pg_amop a WHERE a.oid = d.objid)
+        WHEN 'pg_amproc'::regclass
+            THEN 'amproc: '     || (SELECT (SELECT opfname FROM pg_opfamily WHERE oid = p.amprocfamily)
+                                       || ' [proc ' || p.amprocnum || '] '
+                                       || p.amproclefttype::regtype::text  || ','
+                                       || p.amprocrighttype::regtype::text || ' fn '
+                                       || p.amproc::regprocedure::text
+                                    FROM pg_amproc p WHERE p.oid = d.objid)
+        ELSE 'unhandled[' || d.classid::regclass::text || ']'
+    END AS member
+FROM pg_depend d
+WHERE d.deptype = 'e'
+  AND d.refclassid = 'pg_extension'::regclass
+  AND d.refobjid   = (SELECT oid FROM pg_extension WHERE extname = 'age')
+ORDER BY 1;
 -- =====================================================================
--- COMPARISON: Missing or extra objects (Steps 19-33)
+-- COMPARISON: Missing or extra objects (Steps 19-33b)
 -- Any rows returned indicate a template deficiency.
 -- =====================================================================
 -- Step 19: Functions MISSING after upgrade.
@@ -241,13 +376,20 @@ ORDER BY 1;
 ----------------
 (0 rows)
 
--- Step 21: Function PROPERTY changes (volatility, strictness, kind, return type).
+-- Step 21: Function PROPERTY changes
+-- (kind, volatility, strictness, return type, return-set, binding,
+--  body/symbol). The probin/prosrc check catches:
+--   * a C function whose symbol was renamed in the upgrade template
+--   * a SQL/plpgsql function whose body was changed in either path
+--   * a language change between the fresh and upgrade installs.
 SELECT f.proname || '(' || f.args || ')' AS function_name,
-       CASE WHEN f.prokind    <> u.prokind    THEN 'prokind: '    || f.prokind    || '->' || u.prokind    END AS kind_change,
-       CASE WHEN f.provolatile<> u.provolatile THEN 'volatile: '  || f.provolatile|| '->' || u.provolatile END AS volatility_change,
-       CASE WHEN f.proisstrict<> u.proisstrict THEN 'strict: '    || f.proisstrict|| '->' || u.proisstrict END AS strict_change,
-       CASE WHEN f.rettype    <> u.rettype     THEN 'rettype: '   || f.rettype    || '->' || u.rettype     END AS rettype_change,
-       CASE WHEN f.proretset  <> u.proretset   THEN 'retset: '    || f.proretset  || '->' || u.proretset   END AS retset_change
+       CASE WHEN f.prokind     <> u.prokind     THEN 'prokind: '    || f.prokind     || '->' || u.prokind     END AS kind_change,
+       CASE WHEN f.provolatile <> u.provolatile THEN 'volatile: '   || f.provolatile || '->' || u.provolatile END AS volatility_change,
+       CASE WHEN f.proisstrict <> u.proisstrict THEN 'strict: '     || f.proisstrict || '->' || u.proisstrict END AS strict_change,
+       CASE WHEN f.rettype     <> u.rettype     THEN 'rettype: '    || f.rettype     || '->' || u.rettype     END AS rettype_change,
+       CASE WHEN f.proretset   <> u.proretset   THEN 'retset: '     || f.proretset   || '->' || u.proretset   END AS retset_change,
+       CASE WHEN f.probin      <> u.probin      THEN 'probin: '     || f.probin      || '->' || u.probin      END AS probin_change,
+       CASE WHEN f.prosrc      <> u.prosrc      THEN 'prosrc changed' END                                       AS prosrc_change
 FROM _fresh_funcs f
 JOIN _upgraded_funcs u USING (proname, args)
 WHERE f.provolatile <> u.provolatile
@@ -255,9 +397,11 @@ WHERE f.provolatile <> u.provolatile
    OR f.prokind     <> u.prokind
    OR f.rettype     <> u.rettype
    OR f.proretset   <> u.proretset
+   OR f.probin      <> u.probin
+   OR f.prosrc      <> u.prosrc
 ORDER BY 1;
- function_name | kind_change | volatility_change | strict_change | rettype_change | retset_change 
----------------+-------------+-------------------+---------------+----------------+---------------
+ function_name | kind_change | volatility_change | strict_change | rettype_change | retset_change | probin_change | prosrc_change 
+---------------+-------------+-------------------+---------------+----------------+---------------+---------------+---------------
 (0 rows)
 
 -- Step 22: Relations MISSING after upgrade.
@@ -380,6 +524,28 @@ ORDER BY 1;
 ------------------
 (0 rows)
 
+-- Step 33a: Extension members MISSING after upgrade
+-- (object exists in pg_proc/pg_class/etc. but is not linked to the AGE
+-- extension via pg_depend, i.e. ALTER EXTENSION age ADD ... was forgotten).
+SELECT f.member AS missing_extension_member
+FROM _fresh_extmembers f
+LEFT JOIN _upgraded_extmembers u USING (member)
+WHERE u.member IS NULL
+ORDER BY 1;
+ missing_extension_member 
+--------------------------
+(0 rows)
+
+-- Step 33b: Extension members EXTRA after upgrade.
+SELECT u.member AS extra_extension_member
+FROM _upgraded_extmembers u
+LEFT JOIN _fresh_extmembers f USING (member)
+WHERE f.member IS NULL
+ORDER BY 1;
+ extra_extension_member 
+------------------------
+(0 rows)
+
 -- =====================================================================
 -- SUMMARY (Step 34)
 -- =====================================================================
@@ -391,10 +557,11 @@ SELECT
     (SELECT count(*) FROM _fresh_ops)         = (SELECT count(*) FROM _upgraded_ops)         AS ops_match,
     (SELECT count(*) FROM _fresh_casts)       = (SELECT count(*) FROM _upgraded_casts)       AS casts_match,
     (SELECT count(*) FROM _fresh_opclass)     = (SELECT count(*) FROM _upgraded_opclass)     AS opclass_match,
-    (SELECT count(*) FROM _fresh_constraints) = (SELECT count(*) FROM _upgraded_constraints) AS constraints_match;
- funcs_match | rels_match | types_match | ops_match | casts_match | opclass_match | constraints_match 
--------------+------------+-------------+-----------+-------------+---------------+-------------------
- t           | t          | t           | t         | t           | t             | t
+    (SELECT count(*) FROM _fresh_constraints) = (SELECT count(*) FROM _upgraded_constraints) AS constraints_match,
+    (SELECT count(*) FROM _fresh_extmembers)  = (SELECT count(*) FROM _upgraded_extmembers)  AS extmembers_match;
+ funcs_match | rels_match | types_match | ops_match | casts_match | opclass_match | constraints_match | extmembers_match 
+-------------+------------+-------------+-----------+-------------+---------------+-------------------+------------------
+ t           | t          | t           | t         | t           | t             | t                 | t
 (1 row)
 
 -- =====================================================================
@@ -404,7 +571,8 @@ SELECT
 DROP TABLE _fresh_funcs, _upgraded_funcs, _fresh_rels, _upgraded_rels,
            _fresh_types, _upgraded_types, _fresh_ops, _upgraded_ops,
            _fresh_casts, _upgraded_casts, _fresh_opclass, _upgraded_opclass,
-           _fresh_constraints, _upgraded_constraints;
+           _fresh_constraints, _upgraded_constraints,
+           _fresh_extmembers, _upgraded_extmembers;
 DROP EXTENSION age;
 CREATE EXTENSION age;
 -- Step 36: Remove synthetic upgrade test files from the extension directory.
diff --git a/regress/sql/age_upgrade.sql b/regress/sql/age_upgrade.sql
index f56f7ca93..98ce3e21e 100644
--- a/regress/sql/age_upgrade.sql
+++ b/regress/sql/age_upgrade.sql
@@ -28,16 +28,30 @@
 -- upgrade template.
 --
 -- Compared catalogs:
---   pg_proc     — functions, aggregates, procedures (name, args, properties)
+--   pg_proc     — functions, aggregates, procedures (name, args, properties
+--                 including probin/prosrc to catch C-symbol renames and
+--                 SQL-body changes)
 --   pg_class    — tables, views, sequences, indexes (name, kind)
 --   pg_type     — types (name, type category)
 --   pg_operator — operators (name, left/right types)
 --   pg_cast     — casts involving AGE types (source, target, context)
 --   pg_opclass  — operator classes (name, access method)
 --   pg_constraint — constraints (name, type, table, referenced table)
+--   pg_depend   — extension membership (every AGE-owned object must be
+--                 linked back to the extension via deptype='e'; catches
+--                 a missing ALTER EXTENSION age ADD ... in the template)
 --
 -- All comparison queries should return 0 rows.
 --
+-- Note on synthetic-initial install (step 10): the synthetic '*_initial'
+-- snapshot is built from a fixed historical commit, so its CREATE FUNCTION
+-- statements may reference C symbols that have since been removed from the
+-- current age.so. Step 10 disables check_function_bodies so that dlsym is
+-- deferred to call time; the immediately-following ALTER EXTENSION UPDATE
+-- (step 11) DROPs any such retired functions before any plan can call them.
+-- This lets developers cleanly remove deprecated C entry points without
+-- needing to keep error-raising stubs in age.so.
+--
 
 LOAD 'age';
 SET search_path TO ag_catalog;
@@ -60,16 +74,24 @@ END
 $$;
 
 -- =====================================================================
--- FRESH INSTALL SNAPSHOTS (Steps 2-7)
+-- FRESH INSTALL SNAPSHOTS (Steps 2-7b)
 -- Capture the catalog state from the default CREATE EXTENSION install.
 -- =====================================================================
 
 -- Step 2: Snapshot functions (includes aggregates via prokind).
+-- probin/prosrc capture the binding to the implementation:
+--   * LANGUAGE c        : probin = '$libdir/age', prosrc = C symbol name
+--                         (a renamed/retargeted symbol shows up here)
+--   * LANGUAGE sql/plpgsql: probin = NULL, prosrc = function body text
+--                         (a body change in the upgrade template shows up here)
+--   * LANGUAGE internal : probin = NULL, prosrc = builtin name
 CREATE TEMP TABLE _fresh_funcs AS
 SELECT proname::text,
        pg_get_function_identity_arguments(oid) AS args,
        provolatile::text, proisstrict::text, prokind::text,
-       prorettype::regtype::text AS rettype, proretset::text
+       prorettype::regtype::text AS rettype, proretset::text,
+       COALESCE(probin, '')  AS probin,
+       COALESCE(prosrc, '')  AS prosrc
 FROM pg_proc
 WHERE pronamespace = 'ag_catalog'::regnamespace
 ORDER BY proname, args;
@@ -125,6 +147,58 @@ FROM pg_constraint
 WHERE connamespace = 'ag_catalog'::regnamespace
 ORDER BY conname;
 
+-- Step 7b: Snapshot extension membership (pg_depend deptype='e').
+-- Every object that CREATE EXTENSION owns has a row in pg_depend linking
+-- it to the extension. The upgrade template must produce the same set:
+-- if it CREATEs an object but forgets to ALTER EXTENSION ADD it, the
+-- catalog row exists (so funcs_match/rels_match would pass) but the
+-- pg_depend link is absent and pg_dump --extension would diverge.
+CREATE TEMP TABLE _fresh_extmembers AS
+SELECT
+    CASE d.classid
+        WHEN 'pg_proc'::regclass
+            THEN 'function: '   || d.objid::regprocedure::text
+        WHEN 'pg_type'::regclass
+            THEN 'type: '       || d.objid::regtype::text
+        WHEN 'pg_class'::regclass
+            THEN 'relation: '   || d.objid::regclass::text
+            || ' ('   || (SELECT relkind::text FROM pg_class WHERE oid = d.objid) || ')'
+        WHEN 'pg_operator'::regclass
+            THEN 'operator: '   || d.objid::regoperator::text
+        WHEN 'pg_cast'::regclass
+            THEN 'cast: '       || (SELECT castsource::regtype::text || ' -> ' || casttarget::regtype::text
+                                    FROM pg_cast WHERE oid = d.objid)
+        WHEN 'pg_opclass'::regclass
+            THEN 'opclass: '    || (SELECT opcname || ' (' || (SELECT amname FROM pg_am WHERE oid = opcmethod) || ')'
+                                    FROM pg_opclass WHERE oid = d.objid)
+        WHEN 'pg_constraint'::regclass
+            THEN 'constraint: ' || (SELECT conname || ' on ' || conrelid::regclass::text
+                                    FROM pg_constraint WHERE oid = d.objid)
+        WHEN 'pg_opfamily'::regclass
+            THEN 'opfamily: '   || (SELECT opfname || ' (' || (SELECT amname FROM pg_am WHERE oid = opfmethod) || ')'
+                                    FROM pg_opfamily WHERE oid = d.objid)
+        WHEN 'pg_amop'::regclass
+            THEN 'amop: '       || (SELECT (SELECT opfname FROM pg_opfamily WHERE oid = a.amopfamily)
+                                       || ' [strategy ' || a.amopstrategy || '] '
+                                       || a.amoplefttype::regtype::text  || ','
+                                       || a.amoprighttype::regtype::text || ' op '
+                                       || a.amopopr::regoperator::text
+                                    FROM pg_amop a WHERE a.oid = d.objid)
+        WHEN 'pg_amproc'::regclass
+            THEN 'amproc: '     || (SELECT (SELECT opfname FROM pg_opfamily WHERE oid = p.amprocfamily)
+                                       || ' [proc ' || p.amprocnum || '] '
+                                       || p.amproclefttype::regtype::text  || ','
+                                       || p.amprocrighttype::regtype::text || ' fn '
+                                       || p.amproc::regprocedure::text
+                                    FROM pg_amproc p WHERE p.oid = d.objid)
+        ELSE 'unhandled[' || d.classid::regclass::text || ']'
+    END AS member
+FROM pg_depend d
+WHERE d.deptype = 'e'
+  AND d.refclassid = 'pg_extension'::regclass
+  AND d.refobjid   = (SELECT oid FROM pg_extension WHERE extname = 'age')
+ORDER BY 1;
+
 -- Step 8: Drop AGE entirely.
 DROP EXTENSION age;
 
@@ -133,6 +207,19 @@ SELECT count(*) > 1 AS has_upgrade_path
 FROM pg_available_extension_versions WHERE name = 'age';
 
 -- Step 10: Install AGE at the synthetic initial version.
+--
+-- Disable check_function_bodies for this CREATE only. The synthetic
+-- '*_initial' SQL is pulled from a fixed historical commit and may
+-- declare C functions whose symbols have since been removed from the
+-- current age.so. With check_function_bodies=on, PostgreSQL would dlsym
+-- each such symbol at CREATE FUNCTION time and abort. Deferring the
+-- symbol probe to call time is safe because step 11 (ALTER EXTENSION
+-- UPDATE) immediately runs the upgrade template, which DROPs any
+-- removed-in-HEAD functions before the test (or any user) can call them.
+-- The fresh CREATE EXTENSION at step 35 keeps the GUC at its default,
+-- so any inconsistency between HEAD's SQL and HEAD's age.so is still
+-- caught at install time on the production code path.
+SET check_function_bodies = off;
 DO $$
 DECLARE init_ver text;
 BEGIN
@@ -147,6 +234,7 @@ BEGIN
     EXECUTE format('CREATE EXTENSION age VERSION %L', init_ver);
 END;
 $$;
+RESET check_function_bodies;
 
 -- Step 11: Upgrade to the current (default) version via the stamped template.
 DO $$
@@ -167,16 +255,18 @@ SELECT installed_version = default_version AS upgraded_to_current
 FROM pg_available_extensions WHERE name = 'age';
 
 -- =====================================================================
--- UPGRADED INSTALL SNAPSHOTS (Steps 13-18)
+-- UPGRADED INSTALL SNAPSHOTS (Steps 13-18b)
 -- Capture the catalog state after upgrade from initial to current.
 -- =====================================================================
 
--- Step 13: Snapshot functions.
+-- Step 13: Snapshot functions (probin/prosrc included; see step 2).
 CREATE TEMP TABLE _upgraded_funcs AS
 SELECT proname::text,
        pg_get_function_identity_arguments(oid) AS args,
        provolatile::text, proisstrict::text, prokind::text,
-       prorettype::regtype::text AS rettype, proretset::text
+       prorettype::regtype::text AS rettype, proretset::text,
+       COALESCE(probin, '')  AS probin,
+       COALESCE(prosrc, '')  AS prosrc
 FROM pg_proc
 WHERE pronamespace = 'ag_catalog'::regnamespace
 ORDER BY proname, args;
@@ -233,8 +323,55 @@ FROM pg_constraint
 WHERE connamespace = 'ag_catalog'::regnamespace
 ORDER BY conname;
 
+-- Step 18b: Snapshot extension membership after upgrade (see step 7b).
+CREATE TEMP TABLE _upgraded_extmembers AS
+SELECT
+    CASE d.classid
+        WHEN 'pg_proc'::regclass
+            THEN 'function: '   || d.objid::regprocedure::text
+        WHEN 'pg_type'::regclass
+            THEN 'type: '       || d.objid::regtype::text
+        WHEN 'pg_class'::regclass
+            THEN 'relation: '   || d.objid::regclass::text
+            || ' ('   || (SELECT relkind::text FROM pg_class WHERE oid = d.objid) || ')'
+        WHEN 'pg_operator'::regclass
+            THEN 'operator: '   || d.objid::regoperator::text
+        WHEN 'pg_cast'::regclass
+            THEN 'cast: '       || (SELECT castsource::regtype::text || ' -> ' || casttarget::regtype::text
+                                    FROM pg_cast WHERE oid = d.objid)
+        WHEN 'pg_opclass'::regclass
+            THEN 'opclass: '    || (SELECT opcname || ' (' || (SELECT amname FROM pg_am WHERE oid = opcmethod) || ')'
+                                    FROM pg_opclass WHERE oid = d.objid)
+        WHEN 'pg_constraint'::regclass
+            THEN 'constraint: ' || (SELECT conname || ' on ' || conrelid::regclass::text
+                                    FROM pg_constraint WHERE oid = d.objid)
+        WHEN 'pg_opfamily'::regclass
+            THEN 'opfamily: '   || (SELECT opfname || ' (' || (SELECT amname FROM pg_am WHERE oid = opfmethod) || ')'
+                                    FROM pg_opfamily WHERE oid = d.objid)
+        WHEN 'pg_amop'::regclass
+            THEN 'amop: '       || (SELECT (SELECT opfname FROM pg_opfamily WHERE oid = a.amopfamily)
+                                       || ' [strategy ' || a.amopstrategy || '] '
+                                       || a.amoplefttype::regtype::text  || ','
+                                       || a.amoprighttype::regtype::text || ' op '
+                                       || a.amopopr::regoperator::text
+                                    FROM pg_amop a WHERE a.oid = d.objid)
+        WHEN 'pg_amproc'::regclass
+            THEN 'amproc: '     || (SELECT (SELECT opfname FROM pg_opfamily WHERE oid = p.amprocfamily)
+                                       || ' [proc ' || p.amprocnum || '] '
+                                       || p.amproclefttype::regtype::text  || ','
+                                       || p.amprocrighttype::regtype::text || ' fn '
+                                       || p.amproc::regprocedure::text
+                                    FROM pg_amproc p WHERE p.oid = d.objid)
+        ELSE 'unhandled[' || d.classid::regclass::text || ']'
+    END AS member
+FROM pg_depend d
+WHERE d.deptype = 'e'
+  AND d.refclassid = 'pg_extension'::regclass
+  AND d.refobjid   = (SELECT oid FROM pg_extension WHERE extname = 'age')
+ORDER BY 1;
+
 -- =====================================================================
--- COMPARISON: Missing or extra objects (Steps 19-33)
+-- COMPARISON: Missing or extra objects (Steps 19-33b)
 -- Any rows returned indicate a template deficiency.
 -- =====================================================================
 
@@ -252,13 +389,20 @@ LEFT JOIN _fresh_funcs f USING (proname, args)
 WHERE f.proname IS NULL
 ORDER BY 1;
 
--- Step 21: Function PROPERTY changes (volatility, strictness, kind, return type).
+-- Step 21: Function PROPERTY changes
+-- (kind, volatility, strictness, return type, return-set, binding,
+--  body/symbol). The probin/prosrc check catches:
+--   * a C function whose symbol was renamed in the upgrade template
+--   * a SQL/plpgsql function whose body was changed in either path
+--   * a language change between the fresh and upgrade installs.
 SELECT f.proname || '(' || f.args || ')' AS function_name,
-       CASE WHEN f.prokind    <> u.prokind    THEN 'prokind: '    || f.prokind    || '->' || u.prokind    END AS kind_change,
-       CASE WHEN f.provolatile<> u.provolatile THEN 'volatile: '  || f.provolatile|| '->' || u.provolatile END AS volatility_change,
-       CASE WHEN f.proisstrict<> u.proisstrict THEN 'strict: '    || f.proisstrict|| '->' || u.proisstrict END AS strict_change,
-       CASE WHEN f.rettype    <> u.rettype     THEN 'rettype: '   || f.rettype    || '->' || u.rettype     END AS rettype_change,
-       CASE WHEN f.proretset  <> u.proretset   THEN 'retset: '    || f.proretset  || '->' || u.proretset   END AS retset_change
+       CASE WHEN f.prokind     <> u.prokind     THEN 'prokind: '    || f.prokind     || '->' || u.prokind     END AS kind_change,
+       CASE WHEN f.provolatile <> u.provolatile THEN 'volatile: '   || f.provolatile || '->' || u.provolatile END AS volatility_change,
+       CASE WHEN f.proisstrict <> u.proisstrict THEN 'strict: '     || f.proisstrict || '->' || u.proisstrict END AS strict_change,
+       CASE WHEN f.rettype     <> u.rettype     THEN 'rettype: '    || f.rettype     || '->' || u.rettype     END AS rettype_change,
+       CASE WHEN f.proretset   <> u.proretset   THEN 'retset: '     || f.proretset   || '->' || u.proretset   END AS retset_change,
+       CASE WHEN f.probin      <> u.probin      THEN 'probin: '     || f.probin      || '->' || u.probin      END AS probin_change,
+       CASE WHEN f.prosrc      <> u.prosrc      THEN 'prosrc changed' END                                       AS prosrc_change
 FROM _fresh_funcs f
 JOIN _upgraded_funcs u USING (proname, args)
 WHERE f.provolatile <> u.provolatile
@@ -266,6 +410,8 @@ WHERE f.provolatile <> u.provolatile
    OR f.prokind     <> u.prokind
    OR f.rettype     <> u.rettype
    OR f.proretset   <> u.proretset
+   OR f.probin      <> u.probin
+   OR f.prosrc      <> u.prosrc
 ORDER BY 1;
 
 -- Step 22: Relations MISSING after upgrade.
@@ -352,6 +498,22 @@ LEFT JOIN _fresh_constraints f USING (conname, contype, table_name)
 WHERE f.conname IS NULL
 ORDER BY 1;
 
+-- Step 33a: Extension members MISSING after upgrade
+-- (object exists in pg_proc/pg_class/etc. but is not linked to the AGE
+-- extension via pg_depend, i.e. ALTER EXTENSION age ADD ... was forgotten).
+SELECT f.member AS missing_extension_member
+FROM _fresh_extmembers f
+LEFT JOIN _upgraded_extmembers u USING (member)
+WHERE u.member IS NULL
+ORDER BY 1;
+
+-- Step 33b: Extension members EXTRA after upgrade.
+SELECT u.member AS extra_extension_member
+FROM _upgraded_extmembers u
+LEFT JOIN _fresh_extmembers f USING (member)
+WHERE f.member IS NULL
+ORDER BY 1;
+
 -- =====================================================================
 -- SUMMARY (Step 34)
 -- =====================================================================
@@ -364,7 +526,8 @@ SELECT
     (SELECT count(*) FROM _fresh_ops)         = (SELECT count(*) FROM _upgraded_ops)         AS ops_match,
     (SELECT count(*) FROM _fresh_casts)       = (SELECT count(*) FROM _upgraded_casts)       AS casts_match,
     (SELECT count(*) FROM _fresh_opclass)     = (SELECT count(*) FROM _upgraded_opclass)     AS opclass_match,
-    (SELECT count(*) FROM _fresh_constraints) = (SELECT count(*) FROM _upgraded_constraints) AS constraints_match;
+    (SELECT count(*) FROM _fresh_constraints) = (SELECT count(*) FROM _upgraded_constraints) AS constraints_match,
+    (SELECT count(*) FROM _fresh_extmembers)  = (SELECT count(*) FROM _upgraded_extmembers)  AS extmembers_match;
 
 -- =====================================================================
 -- CLEANUP (Steps 35-36)
@@ -374,7 +537,8 @@ SELECT
 DROP TABLE _fresh_funcs, _upgraded_funcs, _fresh_rels, _upgraded_rels,
            _fresh_types, _upgraded_types, _fresh_ops, _upgraded_ops,
            _fresh_casts, _upgraded_casts, _fresh_opclass, _upgraded_opclass,
-           _fresh_constraints, _upgraded_constraints;
+           _fresh_constraints, _upgraded_constraints,
+           _fresh_extmembers, _upgraded_extmembers;
 DROP EXTENSION age;
 CREATE EXTENSION age;