diff --git a/repl.lua b/repl.lua
index 03a6eb9..dbb0c3c 100644
--- a/repl.lua
+++ b/repl.lua
@@ -151,6 +151,8 @@ Meta commands:
   :tree [<depth>]         scan cwd file-tree, inject as [project] block in system prompt
   :tree refresh           re-scan with last opts (or config defaults)
   :tree off               clear the [project] block
+  :diff [<git-args>]      git diff <args> -> inject as [diff ...] exec_output
+                          examples: :diff   :diff --cached   :diff main..feature
   :delegate <p> <prompt>  one-shot sub-broker call to preset <p>; prints reply
   :help                   this message
 ]]
@@ -684,6 +686,15 @@ function M.run(config)
         end
     end
 
+    -- Phase 6 (B1): every git invocation that flows back into context
+    -- MUST suppress git's interactive pager + color output. Forkpty
+    -- makes git think stdout is a TTY, which enables both. Helper
+    -- prepends `git --no-pager -c color.ui=never <subcmd_and_args>`;
+    -- used by :diff and the @<r1>..<r2> @-mention path in commit #4.
+    local function _git_clean_cmd(subcmd_and_args)
+        return "git --no-pager -c color.ui=never " .. subcmd_and_args
+    end
+
     -- Phase 6 (§6 + N4): project file-tree scanner. Prefers
     -- `git -C <dir> ls-files --cached --others --exclude-standard`
     -- when <dir> is inside a git repo (free .gitignore honor);
@@ -1763,6 +1774,29 @@ function M.run(config)
     --   :tree <N>        scan with depth=N; cached as _project_opts
     --   :tree refresh    re-scan with cached opts; else config defaults
     --   :tree off        clear ctx.project AND ctx._project_opts
+    -- Phase 6: :diff meta — `git diff <args>` (B1-clean), appends as
+    -- [diff <args>]\n<output> exec_output. Reads cwd at invocation
+    -- time (R6: differs from :tree's scan-time cwd capture). Empty
+    -- diff or git failure emits status and skips — never pollutes
+    -- context with empty or error noise.
+    meta.diff = function(args)
+        args = (args or ""):gsub("^%s+", ""):gsub("%s+$", "")
+        local cmd = _git_clean_cmd("diff " .. args)
+        local out, code = executor.exec(cmd)
+        if code ~= 0 then
+            renderer.status(("diff failed (exit %d): %s")
+                            :format(code, args == "" and "(working tree)" or args))
+            return
+        end
+        if not out or out:gsub("%s", "") == "" then
+            renderer.status(("(no diff): %s"):format(
+                args == "" and "(working tree)" or args))
+            return
+        end
+        local label = args == "" and "(working tree)" or args
+        ctx:append_exec_output(("[diff %s]\n%s"):format(label, out))
+        renderer.status(("diff injected: %s (%d bytes)"):format(label, #out))
+    end
     meta.tree = function(args)
         local sub = (args or ""):match("^%s*(%S*)") or ""
         if sub == "off" then