diff --git a/config.lua b/config.lua
index 9c5370a..ede80da 100644
--- a/config.lua
+++ b/config.lua
@@ -123,4 +123,27 @@ return {
     --     -- Default 8. Bump for long-running goals; cap low for testing.
     --     max_norris_steps = 8,
     -- },
+
+    -- Phase 4 (docs/PHASE4.md): cross-session memory.jsonl + startup
+    -- injection + :memory management surface. The block is OFF by
+    -- default (no startup injection); uncomment to tune. Note that
+    -- :remember / :memory list / :memory forget / :memory summarize
+    -- all work without this block — they store to <history.dir>/
+    -- memory.jsonl regardless. The block only configures the
+    -- injection-into-system-prompt behavior at startup.
+    --
+    -- memory = {
+    --     -- Cap on total characters injected at startup. ~2000 chars ≈
+    --     -- 500 tokens. LRU-by-ts selection if your memory.jsonl has
+    --     -- more recent items than fit. Older items remain in the
+    --     -- file; only injection is bounded. Suppressed entirely in
+    --     -- Norris mode (R-C1).
+    --     inject_max_chars = 2000,
+    --
+    --     -- Which configured model to use for :memory summarize.
+    --     -- Defaults to the active model when nil. Use "fast" for
+    --     -- speed; "deep" or "cloud" for better extraction quality
+    --     -- (cloud may have variable cost per session).
+    --     summarizer_model = "fast",
+    -- },
 }