diff --git a/clearwing/sandbox/hunter_sandbox.py b/clearwing/sandbox/hunter_sandbox.py
index c0e87f2f..a0d6fbd0 100644
--- a/clearwing/sandbox/hunter_sandbox.py
+++ b/clearwing/sandbox/hunter_sandbox.py
@@ -79,8 +79,12 @@ def __init__(
         default_cpus: float | None = None,
         backend: SandboxBackend | None = None,
         gvisor_runtime: str | None = None,
+        default_memory_mb: int = 4096,
     ):
         self._validate_cpu_limit(default_cpus, name="default_cpus")
+        if type(default_memory_mb) is not int or not 512 <= default_memory_mb <= 16384:
+            raise ValueError("default_memory_mb must be an integer between 512 and 16384")
+        self.default_memory_mb = default_memory_mb
         self.repo_path = os.path.abspath(repo_path)
         self.languages = languages or []
         self.sanitizers = sanitizers or ["asan", "ubsan"]
@@ -315,7 +319,7 @@ def _build_variant_image(self, sanitizers: list[str]) -> str:
     def spawn(
         self,
         session_id: str | None = None,
-        memory_mb: int = 2048,
+        memory_mb: int | None = None,
         timeout_seconds: int = 300,
         scratch_mount: bool = True,
         variant: list[str] | None = None,
@@ -383,7 +387,7 @@ def spawn(
             policy="sourcehunt",
             isolation="enhanced" if runtime else "default",
             mounts=mounts,
-            memory_mb=memory_mb,
+            memory_mb=self.default_memory_mb if memory_mb is None else memory_mb,
             cpus=resolved_cpus,
             timeout_seconds=timeout_seconds,
             env=env,
diff --git a/clearwing/sourcehunt/commit_monitor.py b/clearwing/sourcehunt/commit_monitor.py
index 49b3acb8..48f85e69 100644
--- a/clearwing/sourcehunt/commit_monitor.py
+++ b/clearwing/sourcehunt/commit_monitor.py
@@ -45,6 +45,7 @@ class CommitMonitorConfig:
     depth: str = "standard"
     budget_usd: float = 0.0
     sandbox_cpus: float | None = None
+    sandbox_memory_mb: int | None = None
     enable_semgrep: bool = False
     on_finding: Callable | None = None
     runner_factory: Callable | None = None  # test injection point
@@ -277,6 +278,7 @@ def _run_sourcehunt_on(self, files: list[str]) -> list[Finding]:
                 output_dir=self.config.output_dir,
                 provider_manager=provider_manager,
                 sandbox_cpus=self.config.sandbox_cpus,
+                sandbox_memory_mb=self.config.sandbox_memory_mb,
                 enable_semgrep=self.config.enable_semgrep,
             )
         try:
diff --git a/clearwing/sourcehunt/config.py b/clearwing/sourcehunt/config.py
index df160341..705392f6 100644
--- a/clearwing/sourcehunt/config.py
+++ b/clearwing/sourcehunt/config.py
@@ -102,6 +102,7 @@ class HuntTuning:
     campaign_hint: str | None = None
     gvisor_runtime: str | None = None
     sandbox_cpus: float | None = None  # None = auto, 0 = unlimited
+    sandbox_memory_mb: int | None = None  # None = 4096 MiB
     nday_filter_batch_size: int = 10
     reveng_batch_size: int = 8
     # Per-field character cap for trace-step code_snippet and note strings.
diff --git a/clearwing/sourcehunt/proof/engine.py b/clearwing/sourcehunt/proof/engine.py
index ef7e04e7..a013ca29 100644
--- a/clearwing/sourcehunt/proof/engine.py
+++ b/clearwing/sourcehunt/proof/engine.py
@@ -88,6 +88,7 @@ class ProofRunConfig:
     falsify: bool = True
     gvisor_runtime: str | None = None
     sandbox_cpus: float | None = None
+    sandbox_memory_mb: int | None = None
     evaluation_hints: dict[str, Any] = field(default_factory=dict)
 
 
@@ -1007,10 +1008,13 @@ def _build_sandbox_runner(
                 default_cpus=self.config.sandbox_cpus,
             )
             self._sandbox.prepare_environment()
-            container = self._sandbox.spawn(
-                session_id=self.config.session_id or None,
-                runtime=self.config.gvisor_runtime,
-            )
+            spawn_kwargs = {
+                "session_id": self.config.session_id or None,
+                "runtime": self.config.gvisor_runtime,
+            }
+            if self.config.sandbox_memory_mb is not None:
+                spawn_kwargs["memory_mb"] = self.config.sandbox_memory_mb
+            container = self._sandbox.spawn(**spawn_kwargs)
         except Exception as exc:
             raise ProofPreflightError(
                 f"Unable to start the required C/C++ analysis sandbox: {exc}",
diff --git a/clearwing/sourcehunt/runner.py b/clearwing/sourcehunt/runner.py
index a45361e3..3f4c3782 100644
--- a/clearwing/sourcehunt/runner.py
+++ b/clearwing/sourcehunt/runner.py
@@ -420,6 +420,7 @@ def __init__(
         respect_gitignore: bool = False,
         live: bool = False,
         sandbox_cpus: float | None = None,
+        sandbox_memory_mb: int | None = None,
         *,
         config: SourceHuntConfig | None = None,
         flow: str = "legacy",
@@ -558,6 +559,9 @@ def __init__(
             campaign_hint = campaign_hint if campaign_hint is not None else h.campaign_hint
             gvisor_runtime = gvisor_runtime if gvisor_runtime is not None else h.gvisor_runtime
             sandbox_cpus = sandbox_cpus if sandbox_cpus is not None else h.sandbox_cpus
+            sandbox_memory_mb = (
+                sandbox_memory_mb if sandbox_memory_mb is not None else h.sandbox_memory_mb
+            )
             trace_step_max_chars = (
                 h.trace_step_max_chars if trace_step_max_chars is None else trace_step_max_chars
             )
@@ -629,6 +633,10 @@ def __init__(
         trace_step_max_chars = max(0, trace_step_max_chars)
         if sandbox_cpus is not None and (not math.isfinite(sandbox_cpus) or sandbox_cpus < 0):
             raise ValueError("sandbox_cpus must be a finite number greater than or equal to 0")
+        if sandbox_memory_mb is not None and (
+            type(sandbox_memory_mb) is not int or not 512 <= sandbox_memory_mb <= 16384
+        ):
+            raise ValueError("sandbox_memory_mb must be an integer between 512 and 16384")
         normalized_target_files = self._normalize_target_files(target_files or ())
         target_window_lines = 480 if target_window_lines is None else target_window_lines
         if type(target_window_lines) is not int or not 40 <= target_window_lines <= 500:
@@ -788,6 +796,7 @@ def __init__(
         self._enable_behavior_monitor = enable_behavior_monitor
         self._enable_artifact_store = enable_artifact_store
         self._sandbox_cpus = None if sandbox_cpus is None else float(sandbox_cpus)
+        self._sandbox_memory_mb = sandbox_memory_mb
         self._gvisor_runtime = self._check_runtime_available(gvisor_runtime)
         self._preprocessing = preprocessing
         self._enable_semgrep = enable_semgrep
@@ -1308,6 +1317,7 @@ def model_client(route: str) -> AsyncLLMClient | None:
                 falsify=self._falsify,
                 gvisor_runtime=self._gvisor_runtime,
                 sandbox_cpus=self._sandbox_cpus,
+                sandbox_memory_mb=self._sandbox_memory_mb,
                 evaluation_hints=evaluation_hints,
             ),
             model_client_factory=model_client,
@@ -4250,6 +4260,7 @@ def _ensure_sandbox_factory(self, repo_path: str, files: list[FileTarget]) -> No
                 languages=languages,
                 deep_agent_mode=use_deep,
                 default_cpus=self._sandbox_cpus,
+                default_memory_mb=self._sandbox_memory_mb or 4096,
                 gvisor_runtime=self._gvisor_runtime,
             )
             environment_ref = manager.prepare_environment()
@@ -4289,7 +4300,6 @@ def _ensure_sandbox_factory(self, repo_path: str, files: list[FileTarget]) -> No
         if use_deep:
             self.sandbox_factory = lambda **kw: manager.spawn(
                 writable_workspace=True,
-                memory_mb=kw.pop("memory_mb", 16384),
                 timeout_seconds=kw.pop("timeout_seconds", 30),
                 runtime=kw.pop("runtime", gvisor_rt),
                 **kw,
diff --git a/clearwing/ui/commands/sourcehunt.py b/clearwing/ui/commands/sourcehunt.py
index 478a720e..931a6def 100644
--- a/clearwing/ui/commands/sourcehunt.py
+++ b/clearwing/ui/commands/sourcehunt.py
@@ -421,6 +421,13 @@ def add_parser(subparsers):
         metavar="N",
         help="CPU limit per sandbox (default: auto; 0 disables the limit)",
     )
+    parser.add_argument(
+        "--sandbox-memory-mb",
+        type=int,
+        default=None,
+        metavar="MiB",
+        help="Memory limit per sandbox in MiB (default: 4096)",
+    )
     parser.add_argument(
         "--tier-split",
         default="70/25/5",
@@ -1177,6 +1184,7 @@ def handle(cli, args):
                 depth=args.depth,
                 budget_usd=args.budget,
                 sandbox_cpus=args.sandbox_cpus,
+                sandbox_memory_mb=args.sandbox_memory_mb,
                 enable_semgrep=args.semgrep,
                 output_dir=args.output_dir,
                 enable_github_checks=args.github_checks,
@@ -1223,6 +1231,7 @@ def handle(cli, args):
                 depth=args.depth,
                 budget_usd=args.budget,
                 sandbox_cpus=args.sandbox_cpus,
+                sandbox_memory_mb=args.sandbox_memory_mb,
                 enable_semgrep=args.semgrep,
                 enable_github_checks=args.github_checks,
                 github_check_name=args.github_check_name,
@@ -1307,6 +1316,7 @@ def handle(cli, args):
         enable_semgrep=args.semgrep,
         live=args.live,
         sandbox_cpus=args.sandbox_cpus,
+        sandbox_memory_mb=args.sandbox_memory_mb,
         flow=args.flow,
         proof_compile_commands=args.compile_commands,
         proof_validation_manifest=args.validation_manifest,
diff --git a/tests/test_sandbox_writable_workspace.py b/tests/test_sandbox_writable_workspace.py
index a2ba9c6f..46cfe884 100644
--- a/tests/test_sandbox_writable_workspace.py
+++ b/tests/test_sandbox_writable_workspace.py
@@ -130,9 +130,10 @@ def test_spawn_inherits_manager_default(self, tmp_path):
             sandbox = manager.spawn(scratch_mount=False)
 
         assert sandbox.config.cpus == 1.0
+        assert sandbox.config.memory_mb == 4096
 
     def test_spawn_override_wins_over_manager_default(self, tmp_path):
-        manager = HunterSandbox(repo_path=str(tmp_path), default_cpus=1.0)
+        manager = HunterSandbox(repo_path=str(tmp_path), default_cpus=1.0, default_memory_mb=6144)
 
         with (
             patch.object(
@@ -140,9 +141,24 @@ def test_spawn_override_wins_over_manager_default(self, tmp_path):
             ),
             patch.object(SandboxContainer, "start", return_value="cid"),
         ):
-            sandbox = manager.spawn(scratch_mount=False, cpus=2.5)
+            sandbox = manager.spawn(scratch_mount=False, cpus=2.5, memory_mb=8192)
 
         assert sandbox.config.cpus == 2.5
+        assert sandbox.config.memory_mb == 8192
+
+        with (
+            patch.object(
+                HunterSandbox, "_prepare_variant_environment", return_value="sandbox:test"
+            ),
+            patch.object(SandboxContainer, "start", return_value="cid"),
+        ):
+            inherited = manager.spawn(scratch_mount=False)
+        assert inherited.config.memory_mb == 6144
+
+    @pytest.mark.parametrize("value", [0, 511, 16385, 1.5, True, "4096"])
+    def test_invalid_manager_memory_limit_rejected(self, tmp_path, value):
+        with pytest.raises(ValueError, match="default_memory_mb"):
+            HunterSandbox(repo_path=str(tmp_path), default_memory_mb=value)
 
 
 class TestSourceHuntSandboxCpuWiring:
@@ -168,13 +184,13 @@ def test_runner_passes_override_to_manager_and_removes_hardcoded_limit(self):
             languages=["c"],
             deep_agent_mode=True,
             default_cpus=1.5,
+            default_memory_mb=4096,
             gvisor_runtime=None,
         )
         assert runner.sandbox_factory is not None
         runner.sandbox_factory()
         manager.spawn.assert_called_once_with(
             writable_workspace=True,
-            memory_mb=16384,
             timeout_seconds=30,
             runtime=None,
         )
@@ -229,6 +245,88 @@ def test_cli_flag_and_default(self):
         assert automatic.sandbox_cpus is None
 
 
+class TestSourceHuntSandboxMemoryWiring:
+    def test_constrained_and_deep_modes_default_to_4096(self):
+        from clearwing.sourcehunt.runner import SourceHuntRunner
+
+        for depth in ("standard", "deep"):
+            manager = MagicMock()
+            manager.default_cpu_limit = 1.0
+            manager.available_cpus = 4.0
+            with patch("clearwing.sourcehunt.runner.HunterSandbox", return_value=manager) as cls:
+                runner = SourceHuntRunner(repo_url="test", depth=depth, max_parallel=1)
+                runner._ensure_sandbox_factory("/tmp/repo", [{"language": "c"}])
+
+            assert cls.call_args.kwargs["default_memory_mb"] == 4096
+            runner.sandbox_factory()
+            assert "memory_mb" not in manager.spawn.call_args.kwargs
+
+    def test_structured_tuning_and_explicit_override(self):
+        from clearwing.sourcehunt import HuntTuning, SourceHuntConfig, TargetConfig
+        from clearwing.sourcehunt.runner import SourceHuntRunner
+
+        config = SourceHuntConfig(
+            target=TargetConfig(repo_url="test"),
+            tuning=HuntTuning(sandbox_memory_mb=6144),
+        )
+        assert SourceHuntRunner(config=config)._sandbox_memory_mb == 6144
+        assert SourceHuntRunner(config=config, sandbox_memory_mb=8192)._sandbox_memory_mb == 8192
+
+    def test_explicit_limit_reaches_new_manager(self):
+        from clearwing.sourcehunt.runner import SourceHuntRunner
+
+        manager = MagicMock()
+        manager.default_cpu_limit = 1.0
+        manager.available_cpus = 4.0
+        with patch("clearwing.sourcehunt.runner.HunterSandbox", return_value=manager) as cls:
+            runner = SourceHuntRunner(repo_url="test", sandbox_memory_mb=6144)
+            runner._ensure_sandbox_factory("/tmp/repo", [{"language": "c"}])
+
+        assert cls.call_args.kwargs["default_memory_mb"] == 6144
+
+    def test_existing_manager_owns_its_memory_default(self, tmp_path):
+        from clearwing.sourcehunt.runner import SourceHuntRunner
+
+        manager = HunterSandbox(repo_path=str(tmp_path), default_memory_mb=6144)
+        runner = SourceHuntRunner(repo_url="test", sandbox_memory_mb=6144)
+        runner._sandbox_manager = manager
+        runner._ensure_sandbox_factory("/tmp/repo", [])
+
+        assert runner.sandbox_factory.__self__ is manager
+        with (
+            patch.object(
+                HunterSandbox, "_prepare_variant_environment", return_value="sandbox:test"
+            ),
+            patch.object(SandboxContainer, "start", return_value="cid"),
+        ):
+            inherited = runner.sandbox_factory(scratch_mount=False)
+            overridden = runner.sandbox_factory(memory_mb=8192, scratch_mount=False)
+
+        assert inherited.config.memory_mb == 6144
+        assert overridden.config.memory_mb == 8192
+
+    @pytest.mark.parametrize("value", [0, 511, 16385, 1.5, True, "4096"])
+    def test_runner_rejects_invalid_memory_limit(self, value):
+        from clearwing.sourcehunt.runner import SourceHuntRunner
+
+        with pytest.raises(ValueError, match="sandbox_memory_mb"):
+            SourceHuntRunner(repo_url="test", sandbox_memory_mb=value)
+
+    def test_cli_flag_and_default(self):
+        import argparse
+
+        from clearwing.ui.commands import sourcehunt
+
+        parser = argparse.ArgumentParser()
+        sourcehunt.add_parser(parser.add_subparsers())
+
+        explicit = parser.parse_args(["sourcehunt", "test-repo", "--sandbox-memory-mb", "6144"])
+        automatic = parser.parse_args(["sourcehunt", "test-repo"])
+
+        assert explicit.sandbox_memory_mb == 6144
+        assert automatic.sandbox_memory_mb is None
+
+
 class TestCopyTreeInto:
     @patch("docker.from_env")
     @patch("subprocess.Popen")
diff --git a/tests/test_sourcehunt_proof_engine.py b/tests/test_sourcehunt_proof_engine.py
index ee83630e..da87b4c8 100644
--- a/tests/test_sourcehunt_proof_engine.py
+++ b/tests/test_sourcehunt_proof_engine.py
@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import json
+from unittest.mock import MagicMock, patch
 
 import pytest
 
@@ -17,6 +18,21 @@
 from clearwing.sourcehunt.runner import SourceHuntRunner
 
 
+def test_proof_sandbox_uses_default_and_explicit_memory_limit(tmp_path) -> None:
+    manager = MagicMock()
+    with patch("clearwing.sourcehunt.proof.engine.HunterSandbox", return_value=manager):
+        default = ProofFlowRunner(repo_url="test", config=ProofRunConfig(output_dir=str(tmp_path)))
+        default._build_sandbox_runner(tmp_path, ["c"])
+        manager.spawn.assert_called_with(session_id=None, runtime=None)
+
+        overridden = ProofFlowRunner(
+            repo_url="test",
+            config=ProofRunConfig(output_dir=str(tmp_path), sandbox_memory_mb=6144),
+        )
+        overridden._build_sandbox_runner(tmp_path, ["c"])
+        manager.spawn.assert_called_with(session_id=None, runtime=None, memory_mb=6144)
+
+
 def _write_sentinel_fixture(path, *, fixed: bool) -> None:
     guard = "    if slice_num >= 0xFFFF:\n        return None\n" if fixed else ""
     (path / "decoder.py").write_text(
@@ -216,13 +232,9 @@ def test_public_runner_merges_proof_and_spend_manifests(tmp_path) -> None:
     assert manifest["metrics"]["totals"]["actions"] == 0
     assert manifest["outputs"]["manifest"] == str(manifest_path)
     assert manifest["outputs"]["ledger"].endswith("spend-ledger.jsonl")
-    assert manifest["outputs"]["spend_summary"].endswith(
-        "spend-summary.json"
-    )
+    assert manifest["outputs"]["spend_summary"].endswith("spend-summary.json")
     spend_summary = json.loads(
-        (output / result.session_id / "spend-summary.json").read_text(
-            encoding="utf-8"
-        )
+        (output / result.session_id / "spend-summary.json").read_text(encoding="utf-8")
     )
     assert spend_summary["call_count"] == 0
     assert spend_summary["status"] == "completed"