diff --git a/docs/content/limitations/builtin-apis/streams-and-readline.mdx b/docs/content/limitations/builtin-apis/streams-and-readline.mdx
index cdd5df47e..0ac0ca3a6 100644
--- a/docs/content/limitations/builtin-apis/streams-and-readline.mdx
+++ b/docs/content/limitations/builtin-apis/streams-and-readline.mdx
@@ -18,6 +18,10 @@
   The cursor never stops between the two UTF-16 units of a supplementary character: where Node's Up or Down movement through a multiline line would, the cursor moves to the character's start or end.
   In JavaScript, a `'history'` listener receives a copy of the history; its changes are written back when the listener returns, but the copy is not `rl.history` itself.
   `rl.history`, `historySize`, `historyIndex`, `crlfDelay`, `tabSize`, `escapeCodeTimeout`, `line`, `cursor`, and `terminal` read as in Node, except that `rl.cursor` of an interface that is not a terminal throws instead of answering `undefined`.
+  `rl[Symbol.dispose]()` closes the interface, and `instanceof` with `readline.Interface` or `readlinePromises.Interface` answers whether the interface came from that module, as in Node.
+  In JavaScript, the input and output can be any expression that evaluates to a stream, such as a function's result or an object's member; a value that is not a stream is unsupported.
+  In JavaScript, `question()` and `setPrompt()` accept a value that is not a string: when such a prompt is written, an interface that is not a terminal throws `ERR_INVALID_ARG_TYPE` as Node does (the `readline/promises` question rejects with it) and the question stays pending, and a terminal interface writes `String(value)`.
+  A terminal interface's prompt that is an object or a symbol, `getPrompt()` while the prompt is not a string, and `getCursorPos()` with an object or symbol prompt are unsupported.
   `readline.cursorTo`, `moveCursor`, `clearLine`, and `clearScreenDown` write to `process.stdout`, `process.stderr`, a writable stream, or nothing for `null` and `undefined`; their callbacks take no parameters.
   The `readline/promises` `Readline` class writes to the same outputs.
   `readline.emitKeypressEvents` emits `'keypress'` events on `process.stdin` or a readable stream, shared with terminal interfaces on that stream as in Node; a listener's first parameter must admit `undefined`, which it receives for escape sequences.
diff --git a/internal/compatibility/generated/node-v24-backlog.json b/internal/compatibility/generated/node-v24-backlog.json
index a02446908..817b723e3 100644
--- a/internal/compatibility/generated/node-v24-backlog.json
+++ b/internal/compatibility/generated/node-v24-backlog.json
@@ -58969,7 +58969,9 @@
             "tests/corpus/5298-readline-abort.cjs",
             "tests/corpus/5299-readline-stdin.ts",
             "tests/corpus/5872-readline-positional-create-interface.mjs",
-            "tests/corpus/5873-readline-promises-namespace.cjs"
+            "tests/corpus/5873-readline-promises-namespace.cjs",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59001,7 +59003,9 @@
             "tests/corpus/5298-readline-abort.cjs",
             "tests/corpus/5299-readline-stdin.ts",
             "tests/corpus/5872-readline-positional-create-interface.mjs",
-            "tests/corpus/5873-readline-promises-namespace.cjs"
+            "tests/corpus/5873-readline-promises-namespace.cjs",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59229,7 +59233,9 @@
             "tests/corpus/5298-readline-abort.cjs",
             "tests/corpus/5299-readline-stdin.ts",
             "tests/corpus/5872-readline-positional-create-interface.mjs",
-            "tests/corpus/5873-readline-promises-namespace.cjs"
+            "tests/corpus/5873-readline-promises-namespace.cjs",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59290,7 +59296,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59322,7 +59330,9 @@
             "tests/corpus/5298-readline-abort.cjs",
             "tests/corpus/5299-readline-stdin.ts",
             "tests/corpus/5872-readline-positional-create-interface.mjs",
-            "tests/corpus/5873-readline-promises-namespace.cjs"
+            "tests/corpus/5873-readline-promises-namespace.cjs",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59405,7 +59415,8 @@
           "confidence": "high",
           "source": "compiler-dedicated:readline.createInterface",
           "tests": [
-            "tests/corpus/1475-readline-closed-stdin.ts"
+            "tests/corpus/1475-readline-closed-stdin.ts",
+            "tests/corpus/5878-readline-dynamic-streams.mjs"
           ]
         }
       }
@@ -59544,7 +59555,8 @@
           "confidence": "high",
           "source": "compiler-dedicated:rl.close",
           "tests": [
-            "tests/corpus/1475-readline-closed-stdin.ts"
+            "tests/corpus/1475-readline-closed-stdin.ts",
+            "tests/corpus/5878-readline-dynamic-streams.mjs"
           ]
         }
       }
@@ -59574,7 +59586,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59604,7 +59618,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59634,7 +59650,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59664,7 +59682,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59694,7 +59714,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59724,7 +59746,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59754,7 +59778,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59784,7 +59810,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59904,7 +59932,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59934,7 +59964,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -59964,7 +59996,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -60022,7 +60056,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
@@ -60052,7 +60088,9 @@
             "tests/corpus/5295-readline-promises-question.ts",
             "tests/corpus/5296-readline-lines.ts",
             "tests/corpus/5297-readline-callback-events.cjs",
-            "tests/corpus/5299-readline-stdin.ts"
+            "tests/corpus/5299-readline-stdin.ts",
+            "tests/corpus/5876-readline-dispose-instanceof.ts",
+            "tests/corpus/5877-readline-question-query.cjs"
           ]
         }
       }
diff --git a/internal/compatibility/generated/node-v24-internal.json b/internal/compatibility/generated/node-v24-internal.json
index 3690ce077..3fc7b1a54 100644
--- a/internal/compatibility/generated/node-v24-internal.json
+++ b/internal/compatibility/generated/node-v24-internal.json
@@ -82492,7 +82492,10 @@
           "tests/corpus/5791-readline-keypress-interfaces.cjs",
           "tests/corpus/5792-readline-keypress-listeners.ts",
           "tests/corpus/5872-readline-positional-create-interface.mjs",
-          "tests/corpus/5873-readline-promises-namespace.cjs"
+          "tests/corpus/5873-readline-promises-namespace.cjs",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs",
+          "tests/corpus/5878-readline-dynamic-streams.mjs"
         ]
       },
       "anchorSource": "chapter"
@@ -82546,7 +82549,9 @@
           "tests/corpus/5298-readline-abort.cjs",
           "tests/corpus/5299-readline-stdin.ts",
           "tests/corpus/5872-readline-positional-create-interface.mjs",
-          "tests/corpus/5873-readline-promises-namespace.cjs"
+          "tests/corpus/5873-readline-promises-namespace.cjs",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -82577,7 +82582,9 @@
           "tests/corpus/5298-readline-abort.cjs",
           "tests/corpus/5299-readline-stdin.ts",
           "tests/corpus/5872-readline-positional-create-interface.mjs",
-          "tests/corpus/5873-readline-promises-namespace.cjs"
+          "tests/corpus/5873-readline-promises-namespace.cjs",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -82797,7 +82804,9 @@
           "tests/corpus/5298-readline-abort.cjs",
           "tests/corpus/5299-readline-stdin.ts",
           "tests/corpus/5872-readline-positional-create-interface.mjs",
-          "tests/corpus/5873-readline-promises-namespace.cjs"
+          "tests/corpus/5873-readline-promises-namespace.cjs",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -82879,7 +82888,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -82910,7 +82921,9 @@
           "tests/corpus/5298-readline-abort.cjs",
           "tests/corpus/5299-readline-stdin.ts",
           "tests/corpus/5872-readline-positional-create-interface.mjs",
-          "tests/corpus/5873-readline-promises-namespace.cjs"
+          "tests/corpus/5873-readline-promises-namespace.cjs",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -82990,7 +83003,8 @@
         "status": "partial",
         "evidence": "compiler-dedicated:readline.createInterface",
         "tests": [
-          "tests/corpus/1475-readline-closed-stdin.ts"
+          "tests/corpus/1475-readline-closed-stdin.ts",
+          "tests/corpus/5878-readline-dynamic-streams.mjs"
         ]
       },
       "anchorSource": "exact"
@@ -83146,7 +83160,8 @@
         "status": "partial",
         "evidence": "compiler-dedicated:rl.close",
         "tests": [
-          "tests/corpus/1475-readline-closed-stdin.ts"
+          "tests/corpus/1475-readline-closed-stdin.ts",
+          "tests/corpus/5878-readline-dynamic-streams.mjs"
         ]
       },
       "anchorSource": "exact"
@@ -83175,7 +83190,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -83204,7 +83221,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -83233,7 +83252,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -83262,7 +83283,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -83291,7 +83314,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -83320,7 +83345,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -83349,7 +83376,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -83378,7 +83407,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -83494,7 +83525,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -83523,7 +83556,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -83552,7 +83587,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -83608,7 +83645,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
@@ -83637,7 +83676,9 @@
           "tests/corpus/5295-readline-promises-question.ts",
           "tests/corpus/5296-readline-lines.ts",
           "tests/corpus/5297-readline-callback-events.cjs",
-          "tests/corpus/5299-readline-stdin.ts"
+          "tests/corpus/5299-readline-stdin.ts",
+          "tests/corpus/5876-readline-dispose-instanceof.ts",
+          "tests/corpus/5877-readline-question-query.cjs"
         ]
       },
       "anchorSource": "exact"
diff --git a/internal/compatibility/static-support.json b/internal/compatibility/static-support.json
index 855d065f7..668c3740c 100644
--- a/internal/compatibility/static-support.json
+++ b/internal/compatibility/static-support.json
@@ -199,13 +199,13 @@
     {"chapter": "events", "symbols": ["CustomEvent", "detail"], "status": "partial", "evidence": ["tests/corpus/5130-event-target-dispatch.js", "tests/corpus/5132-event-target-typed.ts"]},
     {"chapter": "events", "symbols": ["events.errorMonitor"], "status": "partial", "evidence": ["tests/corpus/5134-events-error-monitor.ts", "tests/corpus/5136-events-error-monitor-string-name.ts", "tests/corpus/5137-events-error-monitor-computed-name.js", "tests/corpus/5138-events-error-monitor-shared-listener.ts"]},
     {"chapter": "events", "symbols": ["events.addAbortListener"], "status": "partial", "evidence": ["tests/corpus/5133-abort-signal-event-target.ts"]},
-    {"chapter": "readline", "symbols": ["readlinePromises.Interface", "readlinePromises.createInterface", "rl.question"], "status": "partial", "evidence": ["tests/corpus/5295-readline-promises-question.ts", "tests/corpus/5296-readline-lines.ts", "tests/corpus/5298-readline-abort.cjs", "tests/corpus/5299-readline-stdin.ts", "tests/corpus/5872-readline-positional-create-interface.mjs", "tests/corpus/5873-readline-promises-namespace.cjs"]},
+    {"chapter": "readline", "symbols": ["readlinePromises.Interface", "readlinePromises.createInterface", "rl.question"], "status": "partial", "evidence": ["tests/corpus/5295-readline-promises-question.ts", "tests/corpus/5296-readline-lines.ts", "tests/corpus/5298-readline-abort.cjs", "tests/corpus/5299-readline-stdin.ts", "tests/corpus/5872-readline-positional-create-interface.mjs", "tests/corpus/5873-readline-promises-namespace.cjs", "tests/corpus/5876-readline-dispose-instanceof.ts", "tests/corpus/5877-readline-question-query.cjs"]},
     {"chapter": "readline", "symbols": ["'history'", "rl.line"], "status": "partial", "evidence": ["tests/corpus/5780-readline-history-options.ts", "tests/corpus/5781-readline-history-options.cjs"]},
     {"chapter": "readline", "symbols": ["'SIGINT'", "'SIGTSTP'", "'SIGCONT'", "line", "cursor", "completer"], "status": "partial", "evidence": ["tests/corpus/5782-readline-terminal-editing.ts", "tests/corpus/5783-readline-terminal-completion.cjs", "tests/corpus/5784-readline-terminal-promises.ts", "tests/corpus/5785-readline-terminal-keys.ts", "tests/corpus/5786-readline-terminal-history.cjs"]},
     {"chapter": "readline", "symbols": ["readline.cursorTo", "readline.moveCursor", "readline.clearLine", "readline.clearScreenDown", "rl.getCursorPos"], "status": "partial", "evidence": ["tests/corpus/5787-readline-cursor-helpers.cjs", "tests/corpus/5789-readline-cursor-pos.cjs"]},
     {"chapter": "readline", "symbols": ["readlinePromises.Readline", "rl.clearLine", "rl.clearScreenDown", "rl.commit", "rl.cursorTo", "rl.moveCursor", "rl.rollback"], "status": "partial", "evidence": ["tests/corpus/5788-readline-promises-readline.ts", "tests/corpus/5789-readline-cursor-pos.cjs"]},
     {"chapter": "readline", "symbols": ["readline.emitKeypressEvents"], "status": "partial", "evidence": ["tests/corpus/5790-readline-keypress-events.ts", "tests/corpus/5791-readline-keypress-interfaces.cjs", "tests/corpus/5792-readline-keypress-listeners.ts"]},
-    {"chapter": "readline", "symbols": ["readline.Interface", "rl.pause", "rl.resume", "rl.prompt", "rl.setPrompt", "rl.getPrompt", "rl.write", "rl", "'close'", "'error'", "'line'", "'pause'", "'resume'"], "status": "partial", "evidence": ["tests/corpus/5295-readline-promises-question.ts", "tests/corpus/5296-readline-lines.ts", "tests/corpus/5297-readline-callback-events.cjs", "tests/corpus/5299-readline-stdin.ts"]},
+    {"chapter": "readline", "symbols": ["readline.Interface", "rl.pause", "rl.resume", "rl.prompt", "rl.setPrompt", "rl.getPrompt", "rl.write", "rl", "'close'", "'error'", "'line'", "'pause'", "'resume'"], "status": "partial", "evidence": ["tests/corpus/5295-readline-promises-question.ts", "tests/corpus/5296-readline-lines.ts", "tests/corpus/5297-readline-callback-events.cjs", "tests/corpus/5299-readline-stdin.ts", "tests/corpus/5876-readline-dispose-instanceof.ts", "tests/corpus/5877-readline-question-query.cjs"]},
     {"chapter": "stream", "symbols": ["stream.addAbortSignal"], "status": "partial", "evidence": ["tests/corpus/5300-stream-add-abort-signal.ts", "tests/corpus/5301-stream-add-abort-signal-errors.cjs"]},
     {"chapter": "stream", "symbols": ["readable.map", "readable.filter", "readable.forEach", "readable.toArray", "readable.some", "readable.find", "readable.every", "readable.flatMap", "readable.drop", "readable.take", "readable.reduce"], "status": "partial", "evidence": ["tests/corpus/5335-stream-operators-values.ts", "tests/corpus/5336-stream-operators-promise-timing.ts", "tests/corpus/5337-stream-operators-concurrency.ts", "tests/corpus/5338-stream-operators-checks.cjs"]},
     {"chapter": "stream", "symbols": ["stream.Readable.from"], "status": "partial", "evidence": ["tests/corpus/5340-readable-from-options.ts", "tests/corpus/5341-readable-from-dynamic.cjs", "tests/corpus/5420-readable-from-generators.ts", "tests/corpus/5421-readable-from-generators.cjs", "tests/corpus/5610-readable-from-sets-and-views.ts", "tests/corpus/5611-readable-from-class-iterables.ts", "tests/corpus/5612-readable-from-iterables.cjs"]},
@@ -348,7 +348,7 @@
     { "chapter": "fs", "signatures": ["`filehandle[Symbol.asyncDispose]()`"], "status": "partial", "evidence": ["tests/corpus/2844-node-disposable-resources.ts"] },
     { "chapter": "fs", "signatures": ["`fsPromises.realpath(path[, options])`"], "status": "partial", "evidence": ["tests/corpus/2940-fsp-realpath.ts"] },
     { "chapter": "fs", "signatures": ["`fsPromises.readdir(path[, options])`"], "status": "partial", "evidence": ["tests/corpus/2942-fsp-readdir-dirent.ts"] },
-    { "chapter": "readline", "signatures": ["`rl[Symbol.dispose]()`"], "status": "partial", "evidence": ["tests/corpus/2844-node-disposable-resources.ts"] },
+    { "chapter": "readline", "signatures": ["`rl[Symbol.dispose]()`"], "status": "partial", "evidence": ["tests/corpus/2844-node-disposable-resources.ts", "tests/corpus/5876-readline-dispose-instanceof.ts"] },
     { "chapter": "timers", "signatures": ["`immediate[Symbol.dispose]()`", "`timeout[Symbol.dispose]()`"], "status": "partial", "evidence": ["tests/corpus/2844-node-disposable-resources.ts"] },
     { "chapter": "stream", "signatures": ["`readable[Symbol.asyncIterator]()`", "`readable.iterator([options])`"], "status": "partial", "evidence": ["tests/corpus/1746-stream-for-await.ts", "tests/corpus/2861-readable-iterator-close.ts"] },
     { "chapter": "stream", "signatures": ["`writable.destroy([error])`"], "status": "partial", "evidence": ["tests/corpus/2897-child-stdin-destroy.ts"] },
@@ -416,7 +416,7 @@
     { "symbols": ["dgram.createSocket", "socket.address", "socket.bind", "socket.close", "socket.connect", "socket.ref", "socket.remoteAddress", "socket.send", "socket.unref"], "status": "partial", "evidence": ["tests/corpus/2597-dgram-send-ladders.cjs"] },
     { "symbols": ["net.SocketAddress", "net.BlockList"], "status": "partial", "evidence": ["tests/corpus/5659-net-blocklist-socketaddress.ts", "tests/fixtures/node-types/net-blocklist.ts"] },
     { "symbols": ["SocketAddress.parse", "BlockList.isBlockList", "blockList.addAddress", "blockList.addAddresses", "blockList.addCIDR", "blockList.addCIDRs", "blockList.addRange", "blockList.addSubnet", "blockList.check", "blockList.clear", "blockList.fromJSON", "blockList.removeAddress", "blockList.removeCIDR", "blockList.removeRange", "blockList.removeSubnet", "blockList.toJSON"], "status": "supported", "evidence": ["tests/corpus/5659-net-blocklist-socketaddress.ts", "tests/fixtures/node-types/net-blocklist.ts"] },
-    { "symbols": ["readline.createInterface", "rl.close"], "status": "partial", "evidence": ["tests/corpus/1475-readline-closed-stdin.ts"] },
+    { "symbols": ["readline.createInterface", "rl.close"], "status": "partial", "evidence": ["tests/corpus/1475-readline-closed-stdin.ts", "tests/corpus/5878-readline-dynamic-streams.mjs"] },
     { "symbols": ["test", "it", "test.skip", "test.todo", "test.only", "describe", "suite", "before", "after", "beforeEach", "afterEach", "context.test", "context.skip", "context.todo", "context.assert"], "status": "partial", "evidence": ["tests/harness/node-test.test.ts"] },
     { "symbols": ["http.request", "http.get", "http.createServer", "https.request", "https.get", "https.createServer", "request.end", "request.destroy", "request.setTimeout", "request.write", "response.end", "response.getHeader", "response.hasHeader", "response.removeHeader", "response.setHeader", "response.write", "response.writeHead", "headersTimeout", "requestTimeout", "timeout", "keepAliveTimeout", "keepAliveTimeoutBuffer"], "status": "partial", "evidence": ["tests/corpus/1780-http-res-surface.ts", "tests/corpus/2672-http-request-response-callback.ts", "tests/corpus/2689-http-server-timeout-properties.ts"] }
   ]
diff --git a/packages/compiler/ambient/scriptc-node-fallback.d.ts b/packages/compiler/ambient/scriptc-node-fallback.d.ts
index 628e14f25..3bf97fe6a 100644
--- a/packages/compiler/ambient/scriptc-node-fallback.d.ts
+++ b/packages/compiler/ambient/scriptc-node-fallback.d.ts
@@ -4006,7 +4006,10 @@ declare module "readline" {
     meta?: boolean;
     shift?: boolean;
   }
-  export interface Interface extends Disposable {
+  export class Interface implements Disposable {
+    /* createInterface creates interfaces; instanceof tells the two
+     * modules' classes apart. */
+    protected constructor();
     /* terminal says whether the interface edits lines as a terminal;
      * line and cursor are the terminal's (line is '' otherwise). history
      * is the history option itself (or the interface's own empty array);
@@ -4121,7 +4124,10 @@ declare module "readline/promises" {
   /* The readline Interface with the promise question: it resolves with
    * the next line, rejects with an AbortError when options.signal aborts,
    * and with ERR_USE_AFTER_CLOSE after close(). */
-  export interface Interface extends Disposable {
+  export class Interface implements Disposable {
+    /* createInterface creates interfaces; instanceof tells the two
+     * modules' classes apart. */
+    protected constructor();
     /* terminal says whether the interface edits lines as a terminal;
      * line and cursor are the terminal's (line is '' otherwise). history
      * is the history option itself (or the interface's own empty array);
diff --git a/packages/compiler/src/backend/llvm/lib-dispatch.ts b/packages/compiler/src/backend/llvm/lib-dispatch.ts
index 31d7ca5c2..16759a592 100644
--- a/packages/compiler/src/backend/llvm/lib-dispatch.ts
+++ b/packages/compiler/src/backend/llvm/lib-dispatch.ts
@@ -83,12 +83,19 @@ export function emitIoLibCall(host: LlvmEmitterContext, e: LibCallExpr): LlValue
     }
     // A signal that is not an AbortSignal throws ERR_INVALID_ARG_TYPE.
     if (mode & 8) host.emitPendingCheck();
+    // readline/promises interfaces are instances of that module's class.
+    if (mode & 32) {
+      host.declare(`declare void @scr_rl_mark_promises(double)`);
+      B.line(`call void @scr_rl_mark_promises(double ${t})`);
+    }
     return { name: t, type: e.type };
   }
-  if (e.fn === "rl.question") {
+  if (e.fn === "rl.question" || e.fn === "rl.questionDyn") {
     // The answer callback MOVES into the interface's registry; throws
-    // Node's use-after-close error (the may-throw seed).
+    // Node's use-after-close error (the may-throw seed), and with a
+    // checked-dynamic query that is not a string, ERR_INVALID_ARG_TYPE.
     host.usesTimers = true;
+    const fn = e.fn === "rl.question" ? "scr_rl_question" : "scr_rl_question_dyn";
     const cbT = e.args[2]!.type;
     if (cbT.kind !== "func")
       throw new InternalCompilerError("llvm emitter bug: rl.question callback not a func");
@@ -101,29 +108,37 @@ export function emitIoLibCall(host: LlvmEmitterContext, e: LibCallExpr): LlValue
           ? "scr_rl_answer_thunk_dyn"
           : "scr_rl_answer_thunk_str";
     host.declare(`declare void @${adapter}(ptr, ptr)`);
-    host.declare(`declare void @scr_rl_question(double, ptr, ptr, ptr)`);
+    host.declare(`declare void @${fn}(double, ptr, ptr, ptr)`);
     B.line(
-      `call void @scr_rl_question(double ${args[0]!.name}, ptr ${args[1]!.name}, ptr ${args[2]!.name}, ptr @${adapter})`,
+      `call void @${fn}(double ${args[0]!.name}, ptr ${args[1]!.name}, ptr ${args[2]!.name}, ptr @${adapter})`,
     );
     host.emitPendingCheck();
     return { name: "", type: e.type };
   }
-  if (e.fn === "rl.questionAsync" || e.fn === "rl.questionAsyncSignal") {
-    // The promise question never throws: closed interfaces and aborted
-    // signals reject the answered promise (+1).
+  if (
+    e.fn === "rl.questionAsync" ||
+    e.fn === "rl.questionAsyncSignal" ||
+    e.fn === "rl.questionAsyncDyn" ||
+    e.fn === "rl.questionAsyncSignalDyn"
+  ) {
+    // The promise question never throws: closed interfaces, aborted
+    // signals and queries that are not strings reject the answered
+    // promise (+1).
     host.usesTimers = true;
     const args = e.args.map((a) => host.emitExpr(a));
+    const dyn = e.fn === "rl.questionAsyncDyn" || e.fn === "rl.questionAsyncSignalDyn";
+    const fn = dyn ? "scr_rl_question_promise_dyn" : "scr_rl_question_promise";
     let signal = "null";
     let add = "null";
-    if (e.fn === "rl.questionAsyncSignal") {
+    if (e.fn === "rl.questionAsyncSignal" || e.fn === "rl.questionAsyncSignalDyn") {
       signal = args[2]!.name;
       host.declare(`declare ptr @scr_events_add_abort_listener(ptr, ptr)`);
       add = "@scr_events_add_abort_listener";
     }
-    host.declare(`declare ptr @scr_rl_question_promise(double, ptr, ptr, ptr)`);
+    host.declare(`declare ptr @${fn}(double, ptr, ptr, ptr)`);
     const t = B.tmp();
     B.line(
-      `${t} = call ptr @scr_rl_question_promise(double ${args[0]!.name}, ptr ${args[1]!.name}, ptr ${signal}, ptr ${add})`,
+      `${t} = call ptr @${fn}(double ${args[0]!.name}, ptr ${args[1]!.name}, ptr ${signal}, ptr ${add})`,
     );
     return host.own({ name: t, type: e.type });
   }
diff --git a/packages/compiler/src/backend/llvm/lib-shared.ts b/packages/compiler/src/backend/llvm/lib-shared.ts
index d01374235..44741edc8 100644
--- a/packages/compiler/src/backend/llvm/lib-shared.ts
+++ b/packages/compiler/src/backend/llvm/lib-shared.ts
@@ -1040,6 +1040,7 @@ export const LIB_FN_SYMS: Record<string, string> = {
   "rl.prompt": "scr_rl_prompt",
   "rl.promptWith": "scr_rl_prompt_with",
   "rl.setPrompt": "scr_rl_set_prompt",
+  "rl.setPromptDyn": "scr_rl_set_prompt_dyn",
   "rl.getPrompt": "scr_rl_get_prompt",
   "rl.write": "scr_rl_write",
   "rl.writeKey": "scr_rl_write_key",
@@ -1055,6 +1056,9 @@ export const LIB_FN_SYMS: Record<string, string> = {
   "rl.terminal": "scr_rl_terminal",
   "rl.line": "scr_rl_line",
   "rl.isTerminal": "scr_rl_is_terminal",
+  "rl.isPromises": "scr_rl_is_promises",
+  "rl.inputFromDyn": "scr_stream_rl_from_dyn",
+  "rl.outputFromDyn": "scr_stream_rl_from_dyn",
   "rl.cursor": "scr_rl_cursor",
   "rl.seq": "scr_rl_seq",
   "rl.moves": "scr_rl_moves",
diff --git a/packages/compiler/src/frontend/lowering/builtins/readline.ts b/packages/compiler/src/frontend/lowering/builtins/readline.ts
index 6baeb65d1..bcf77a39b 100644
--- a/packages/compiler/src/frontend/lowering/builtins/readline.ts
+++ b/packages/compiler/src/frontend/lowering/builtins/readline.ts
@@ -18,6 +18,7 @@ import { READLINE_DOCUMENTED_OPTIONS, fenceOrDropOptionKey } from "../surfaces.j
 import { streamSidesOf } from "../lower-stream.js";
 import type { IrLibFn } from "../../../ir/builtin-signatures.js";
 import { voidizedCallback } from "../lower-server.js";
+import { builtinImportOf } from "./module-bindings.js";
 
 /** The ambient module declaring `d`, or null. */
 function ambientModuleOf(d: ts.Node): string | null {
@@ -270,6 +271,80 @@ function lowerReadlineUiCall(
   return { kind: "seqExpr", stmts, result: recv, type: F64, loc };
 }
 
+/** The module ("readline" or "readline/promises") whose Interface class
+ * `node` names, or null. */
+function interfaceClassModule(lowerer: Lowerer, node: ts.Expression): string | null {
+  const builtin = ts.isIdentifier(node)
+    ? builtinImportOf(lowerer, node)
+    : ts.isPropertyAccessExpression(node) && !node.questionDotToken
+      ? lowerer.builtinMemberOf(node)
+      : null;
+  if (builtin?.member !== "Interface") return null;
+  return builtin.module === "readline" || builtin.module === "readline/promises"
+    ? builtin.module
+    : null;
+}
+
+/** `rl instanceof readline.Interface` and `rl instanceof
+ * readlinePromises.Interface` over a readline Interface: an interface is
+ * an instance of the class of the module that created it (Node's
+ * readline/promises Interface does not extend node:readline's). Null for
+ * other instanceof tests. */
+export function lowerReadlineInstanceof(
+  lowerer: Lowerer,
+  expr: ts.BinaryExpression,
+): IrExpr | null {
+  const module = interfaceClassModule(lowerer, expr.right);
+  if (module === null || !isReadlineTyped(lowerer, expr.left)) return null;
+  const loc = locOf(expr);
+  const recv = lowerer.lowerExprExpecting(expr.left, F64);
+  const isPromises: IrExpr = {
+    kind: "libCall",
+    fn: "rl.isPromises",
+    args: [recv],
+    type: BOOL,
+    loc,
+  };
+  if (module === "readline/promises") return isPromises;
+  return { kind: "unary", op: "!", operand: isPromises, type: BOOL, loc };
+}
+
+/** `rl[Symbol.dispose]()` on a readline Interface: Node's dispose method
+ * calls close(), which does nothing on a closed interface. Null for other
+ * element-access calls. */
+export function lowerReadlineDisposeCall(lowerer: Lowerer, call: ts.CallExpression): IrExpr | null {
+  const access = call.expression;
+  if (!ts.isElementAccessExpression(access) || access.questionDotToken || call.questionDotToken) {
+    return null;
+  }
+  let key = access.argumentExpression;
+  while (ts.isParenthesizedExpression(key)) key = key.expression;
+  if (
+    !ts.isPropertyAccessExpression(key) ||
+    lowerer.stdlibGlobalMember(key, "Symbol") !== "dispose"
+  ) {
+    return null;
+  }
+  if (!isReadlineTyped(lowerer, access.expression)) return null;
+  if (call.arguments.nodes.length > 0) {
+    lowerer.noLowering("readline.Interface[Symbol.dispose] with arguments", call);
+  }
+  const recv = lowerer.lowerExprExpecting(access.expression, F64);
+  return { kind: "libCall", fn: "rl.close", args: [recv], type: VOID, loc: locOf(call) };
+}
+
+/** A question query or setPrompt argument: the string, or for a value
+ * that need not be one (JavaScript), the checked-dynamic value, which the
+ * runtime writes the way Node's kWriteToOutput does (dyn: true). */
+function lowerPromptArg(lowerer: Lowerer, node: ts.Expression): { value: IrExpr; dyn: boolean } {
+  if (lowerer.typeOf(node).flags & ts.TypeFlags.StringLike) {
+    return { value: lowerer.lowerExprExpecting(node, STRING), dyn: false };
+  }
+  const value = lowerer.lowerExpr(node);
+  if (value.type.kind === "string") return { value, dyn: false };
+  return { value: lowerer.coerceInto(node, value, DYN), dyn: true };
+}
+
 /** Method calls on readline Interface receivers (both modules):
  * - question(query, cb) — the callback form; question(query, { signal }?)
  *   — the promise form (readline/promises);
@@ -303,18 +378,20 @@ export function lowerReadlineMethodCall(
     args.length <= 2
   ) {
     const recv = receiver();
-    const query = lowerer.lowerExprExpecting(args[0]!, STRING);
+    const query = lowerPromptArg(lowerer, args[0]!);
     const signal = questionSignal(lowerer, args[1]);
     const type = { kind: "promise", inner: STRING } as const;
     if (signal === null) {
-      return { kind: "libCall", fn: "rl.questionAsync", args: [recv, query], type, loc };
+      const fn = query.dyn ? "rl.questionAsyncDyn" : "rl.questionAsync";
+      return { kind: "libCall", fn, args: [recv, query.value], type, loc };
     }
     const sig = lowerer.lowerExprExpecting(signal, DYN);
-    return { kind: "libCall", fn: "rl.questionAsyncSignal", args: [recv, query, sig], type, loc };
+    const fn = query.dyn ? "rl.questionAsyncSignalDyn" : "rl.questionAsyncSignal";
+    return { kind: "libCall", fn, args: [recv, query.value, sig], type, loc };
   }
   if (name === "question" && args.length === 2) {
     const recv = receiver();
-    const query = lowerer.lowerExprExpecting(args[0]!, STRING);
+    const query = lowerPromptArg(lowerer, args[0]!);
     const cb = lowerer.lowerExpr(args[1]!);
     if (cb.type.kind !== "func" || cb.type.ret.kind !== "void" || cb.type.params.length > 1) {
       lowerer.unsupported(
@@ -331,7 +408,8 @@ export function lowerReadlineMethodCall(
         `question callbacks whose parameter is not 'string' (got '${lowerer.fmt(param)}')`,
       );
     }
-    return { kind: "libCall", fn: "rl.question", args: [recv, query, cb], type: VOID, loc };
+    const fn = query.dyn ? "rl.questionDyn" : "rl.question";
+    return { kind: "libCall", fn, args: [recv, query.value, cb], type: VOID, loc };
   }
   const simple: Record<string, "rl.close" | "rl.pause" | "rl.resume" | "rl.prompt"> = {
     close: "rl.close",
@@ -366,8 +444,9 @@ export function lowerReadlineMethodCall(
   }
   if (name === "setPrompt" && args.length === 1) {
     const recv = receiver();
-    const prompt = lowerer.lowerExprExpecting(args[0]!, STRING);
-    return { kind: "libCall", fn: "rl.setPrompt", args: [recv, prompt], type: VOID, loc };
+    const prompt = lowerPromptArg(lowerer, args[0]!);
+    const fn = prompt.dyn ? "rl.setPromptDyn" : "rl.setPrompt";
+    return { kind: "libCall", fn, args: [recv, prompt.value], type: VOID, loc };
   }
   if (name === "getPrompt" && args.length === 0) {
     return { kind: "libCall", fn: "rl.getPrompt", args: [receiver()], type: STRING, loc };
@@ -871,6 +950,25 @@ export function lowerReadlineCursorCall(
   return { kind: "seqExpr", stmts, result, type: BOOL, loc };
 }
 
+/** A checked-dynamic input or output (a JavaScript function's result, an
+ * object's member, an element that may be undefined) as the stream it
+ * holds: the runtime refuses a value that is not a stream with that
+ * side, and answers null for an output of null or undefined. Other
+ * values pass through. */
+function streamFromDyn(lowerer: Lowerer, node: ts.Expression, output: boolean): IrExpr {
+  let v = lowerer.lowerExpr(node);
+  if (v.type.kind === "union") v = lowerer.coerceInto(node, v, DYN);
+  if (v.type.kind !== "dyn") return v;
+  const loc = locOf(node);
+  return {
+    kind: "libCall",
+    fn: output ? "rl.outputFromDyn" : "rl.inputFromDyn",
+    args: [v, boolLit(output, loc)],
+    type: { kind: "object", className: output ? "%Writable" : "%Readable" },
+    loc,
+  };
+}
+
 /** The interface's input: process.stdin (null) or a readable stream. */
 function lowerInput(lowerer: Lowerer, node: ts.Expression): IrExpr | null {
   if (
@@ -879,7 +977,7 @@ function lowerInput(lowerer: Lowerer, node: ts.Expression): IrExpr | null {
   ) {
     return null;
   }
-  const v = lowerer.lowerExpr(node);
+  const v = streamFromDyn(lowerer, node, false);
   const info = v.type.kind === "object" ? lowerer.classes.get(v.type.className) : undefined;
   const sides = streamSidesOf(lowerer, info);
   if (sides !== "r" && sides !== "rw") {
@@ -904,7 +1002,7 @@ function lowerOutput(lowerer: Lowerer, node: ts.Expression): IrExpr | "stdout" |
     return "none";
   }
   if (ts.isIdentifier(node) && node.text === "undefined") return "none";
-  const v = lowerer.lowerExpr(node);
+  const v = streamFromDyn(lowerer, node, true);
   const info = v.type.kind === "object" ? lowerer.classes.get(v.type.className) : undefined;
   const sides = streamSidesOf(lowerer, info);
   if (sides !== "w" && sides !== "rw") {
@@ -923,8 +1021,8 @@ function lowerOutput(lowerer: Lowerer, node: ts.Expression): IrExpr | "stdout" |
  * stream; the output process.stdout, a writable stream, or absent
  * (prompts are then not written). rl.create's arguments: the mode literal
  * (1 stream input, 2 stream output, 4 stdout output, 8 signal, 16
- * prompt), then the input and output streams when present, crlfDelay,
- * the prompt and the signal when present. An interface that can be a
+ * prompt, 32 node:readline/promises), then the input and output streams
+ * when present, crlfDelay, the prompt and the signal when present. An interface that can be a
  * terminal one (a `terminal` option that is not false, or none with
  * process.stdout as the output, which is a terminal when it is a TTY)
  * goes through rl.terminal with the completer. */
@@ -1107,7 +1205,8 @@ export function lowerReadlineCreateCall(
     (typeof output === "object" ? 2 : 0) |
     (output === "stdout" ? 4 : 0) |
     (signal !== null ? 8 : 0) |
-    (prompt !== null ? 16 : 0);
+    (prompt !== null ? 16 : 0) |
+    (promises ? 32 : 0);
   const args: IrExpr[] = [numLit(mode, loc)];
   if (input !== null) args.push(input);
   if (typeof output === "object") args.push(output);
diff --git a/packages/compiler/src/frontend/lowering/expressions/relational.ts b/packages/compiler/src/frontend/lowering/expressions/relational.ts
index b92c5e7e5..619c0fe37 100644
--- a/packages/compiler/src/frontend/lowering/expressions/relational.ts
+++ b/packages/compiler/src/frontend/lowering/expressions/relational.ts
@@ -32,6 +32,7 @@ import { lowerZlibInstanceOf } from "../builtins/compression.js";
 import { numLit, strLit, varRef } from "../../../ir/build.js";
 import { lowerDisposableStackInstanceOf } from "../builtins/disposable-stack.js";
 import { lowerBlobInstanceof } from "../builtins/blob.js";
+import { lowerReadlineInstanceof } from "../builtins/readline.js";
 import { lowerKeyObjectInstanceof } from "../builtins/key-object.js";
 import { lowerCryptoKeyInstanceof } from "../builtins/webcrypto.js";
 import { lowerNetAddressInstanceof } from "../builtins/net-address.js";
@@ -179,6 +180,8 @@ export function lowerInstanceOf(lowerer: Lowerer, expr: ts.BinaryExpression, loc
     if (cryptoKey) return cryptoKey;
     const netAddress = lowerNetAddressInstanceof(lowerer, expr);
     if (netAddress) return netAddress;
+    const readlineInterface = lowerReadlineInstanceof(lowerer, expr);
+    if (readlineInterface) return readlineInterface;
   }
   if (lowerer.isStdlibGlobal(expr.right, "SharedArrayBuffer")) {
     const value = lowerer.coerceInto(expr.left, lowerer.lowerExpr(expr.left), DYN);
diff --git a/packages/compiler/src/frontend/lowering/lower-calls.ts b/packages/compiler/src/frontend/lowering/lower-calls.ts
index 699f04ec8..ed549e4ff 100644
--- a/packages/compiler/src/frontend/lowering/lower-calls.ts
+++ b/packages/compiler/src/frontend/lowering/lower-calls.ts
@@ -35,6 +35,7 @@ import {
 import { cjsExportCallIgnoresThis, cjsInFileExportGlobalOf } from "./cjs-exports-object.js";
 import { lowerGenMethodCall } from "./lower-generators.js";
 import { lowerClassSymbolMethodCall } from "./symbol-methods.js";
+import { lowerReadlineDisposeCall } from "./builtins/readline.js";
 import { errorToStringCall } from "./error-methods.js";
 import { lowerClassPrototypeAssign, lowerClassPrototypeDescriptors } from "./class-prototypes.js";
 import {
@@ -1683,6 +1684,8 @@ export function lowerCall(lowerer: Lowerer, expr: ts.CallExpression): IrExpr {
     if (timersDispose) return timersDispose;
     const symbolMethod = lowerClassSymbolMethodCall(lowerer, expr);
     if (symbolMethod) return symbolMethod;
+    const readlineDispose = lowerReadlineDisposeCall(lowerer, expr);
+    if (readlineDispose) return readlineDispose;
     lowerer.fenceUnsupportedFetchConstructorMember(expr.expression);
     lowerer.fenceStaticResponseMember(expr.expression, "call");
     lowerer.fenceStaticHeadersMember(expr.expression, "call");
diff --git a/packages/compiler/src/ir/builtin-effects.ts b/packages/compiler/src/ir/builtin-effects.ts
index 4d4193f73..826151009 100644
--- a/packages/compiler/src/ir/builtin-effects.ts
+++ b/packages/compiler/src/ir/builtin-effects.ts
@@ -448,6 +448,7 @@ export const MAY_THROW_LIB_FNS: ReadonlySet<IrLibFn> = new Set([
   "https.requestFn",
   "https.requestFnCb",
   "rl.question",
+  "rl.questionDyn",
   "rl.checkOptions",
   "rl.checkCompleter",
   "readable.fromArr",
@@ -470,6 +471,11 @@ export const MAY_THROW_LIB_FNS: ReadonlySet<IrLibFn> = new Set([
   "rl.resume",
   "rl.prompt",
   "rl.promptWith",
+  "rl.setPromptDyn",
+  "rl.getPrompt",
+  "rl.cursorPos",
+  "rl.inputFromDyn",
+  "rl.outputFromDyn",
   "rl.write",
   "rl.writeKey",
   "rl.cursor",
diff --git a/packages/compiler/src/ir/builtin-signatures.ts b/packages/compiler/src/ir/builtin-signatures.ts
index 2a0e5124a..c55444e60 100644
--- a/packages/compiler/src/ir/builtin-signatures.ts
+++ b/packages/compiler/src/ir/builtin-signatures.ts
@@ -4019,6 +4019,14 @@ export const LIB_FN_SIGS = defineLibFnSignatures({
     argTypes: [F64, STRING, DYN],
     result: { kind: "promise", inner: STRING },
   },
+  /** The question forms with a checked-dynamic query (a JavaScript value
+   * that need not be a string). */
+  "rl.questionDyn": { argTypes: [F64, DYN, null], result: VOID },
+  "rl.questionAsyncDyn": { argTypes: [F64, DYN], result: { kind: "promise", inner: STRING } },
+  "rl.questionAsyncSignalDyn": {
+    argTypes: [F64, DYN, DYN],
+    result: { kind: "promise", inner: STRING },
+  },
   "rl.close": { argTypes: [F64], result: VOID },
   "rl.pause": { argTypes: [F64], result: VOID },
   "rl.resume": { argTypes: [F64], result: VOID },
@@ -4026,6 +4034,7 @@ export const LIB_FN_SIGS = defineLibFnSignatures({
   /** prompt(preserveCursor): [handle, preserveCursor] */
   "rl.promptWith": { argTypes: [F64, BOOL], result: VOID },
   "rl.setPrompt": { argTypes: [F64, STRING], result: VOID },
+  "rl.setPromptDyn": { argTypes: [F64, DYN], result: VOID },
   "rl.getPrompt": { argTypes: [F64], result: STRING },
   "rl.write": { argTypes: [F64, STRING], result: VOID },
   /** write(data, key): [handle, hasData, data, hasKey, hasName, name,
@@ -4058,6 +4067,14 @@ export const LIB_FN_SIGS = defineLibFnSignatures({
   "rl.terminal": { argTypes: [F64, F64, BOOL, DYN, BOOL], result: VOID },
   "rl.line": { argTypes: [F64], result: STRING },
   "rl.isTerminal": { argTypes: [F64], result: BOOL },
+  "rl.isPromises": { argTypes: [F64], result: BOOL },
+  /** createInterface's input or output as a checked-dynamic value:
+   * [value, output] — the stream; refused when it is not one. */
+  "rl.inputFromDyn": { argTypes: [DYN, BOOL], result: { kind: "object", className: "%Readable" } },
+  "rl.outputFromDyn": {
+    argTypes: [DYN, BOOL],
+    result: { kind: "object", className: "%Writable" },
+  },
   "rl.cursor": { argTypes: [F64], result: F64 },
   /** readline.cursorTo / moveCursor / clearLine / clearScreenDown: rl.seq
    * [kind (0-3), the first and second numbers, whether the second is
diff --git a/packages/compiler/src/ir/runtime-features.ts b/packages/compiler/src/ir/runtime-features.ts
index 34ec76f8d..9abe15345 100644
--- a/packages/compiler/src/ir/runtime-features.ts
+++ b/packages/compiler/src/ir/runtime-features.ts
@@ -151,6 +151,8 @@ const STREAM_LIB_FNS: ReadonlySet<IrLibFn> = new Set([
   "fileHandle.createWriteStream",
   "fs.createReadStream",
   "fs.createWriteStream",
+  "rl.inputFromDyn",
+  "rl.outputFromDyn",
   "sp.finished",
   "sp.pipeline",
   "sp.pipelineStages",
@@ -356,12 +358,16 @@ const PROCESS_EVENT_LIB_FNS: ReadonlySet<IrLibFn> = new Set([
   "rl.question",
   "rl.questionAsync",
   "rl.questionAsyncSignal",
+  "rl.questionDyn",
+  "rl.questionAsyncDyn",
+  "rl.questionAsyncSignalDyn",
   "rl.close",
   "rl.pause",
   "rl.resume",
   "rl.prompt",
   "rl.promptWith",
   "rl.setPrompt",
+  "rl.setPromptDyn",
   "rl.getPrompt",
   "rl.write",
   "rl.writeKey",
@@ -378,6 +384,7 @@ const PROCESS_EVENT_LIB_FNS: ReadonlySet<IrLibFn> = new Set([
   "rl.terminal",
   "rl.line",
   "rl.isTerminal",
+  "rl.isPromises",
   "rl.cursor",
   "rl.seq",
   "rl.moves",
diff --git a/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/5876-readline-dispose-instanceof.ts.json b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/5876-readline-dispose-instanceof.ts.json
new file mode 100644
index 000000000..959c704b0
--- /dev/null
+++ b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/5876-readline-dispose-instanceof.ts.json
@@ -0,0 +1,6 @@
+{
+ "order": [
+  "<repo>/tests/corpus/5876-readline-dispose-instanceof.ts"
+ ],
+ "diags": []
+}
diff --git a/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/5877-readline-question-query.cjs.json b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/5877-readline-question-query.cjs.json
new file mode 100644
index 000000000..fe2bcfeee
--- /dev/null
+++ b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/5877-readline-question-query.cjs.json
@@ -0,0 +1,6 @@
+{
+ "order": [
+  "<repo>/tests/corpus/5877-readline-question-query.cjs"
+ ],
+ "diags": []
+}
diff --git a/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/5878-readline-dynamic-streams.mjs.json b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/5878-readline-dynamic-streams.mjs.json
new file mode 100644
index 000000000..ddd665241
--- /dev/null
+++ b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/5878-readline-dynamic-streams.mjs.json
@@ -0,0 +1,6 @@
+{
+ "order": [
+  "<repo>/tests/corpus/5878-readline-dynamic-streams.mjs"
+ ],
+ "diags": []
+}
diff --git a/packages/runtime/src/scr_readline.c b/packages/runtime/src/scr_readline.c
index e031a4e34..1bc48bbe7 100644
--- a/packages/runtime/src/scr_readline.c
+++ b/packages/runtime/src/scr_readline.c
@@ -185,11 +185,28 @@ void scr_rl_do_resume(ScrRl *rl) {
   }
 }
 
+bool scr_rl_prompt_writable(ScrRl *rl) {
+  if (!rl->prompt_value) return true;
+  scr_dyn_arg_type_fail("stringToWrite", "of type string", rl->prompt_value);
+  return false;
+}
+
 static void scr_rl_prompt_now(ScrRl *rl) {
   if (rl->paused) scr_rl_do_resume(rl);
   if (scr_exc_pending()) return;
   if (rl->tty) scr_rl_tty_ops->prompt(rl, false);
-  else scr_rl_write_out(rl, rl->prompt);
+  else if (scr_rl_prompt_writable(rl)) scr_rl_write_out(rl, rl->prompt);
+}
+
+/* setPrompt(this[kOldPrompt]) when a question is answered or cancelled */
+static void scr_rl_restore_prompt(ScrRl *rl) {
+  if (!rl->old_prompt) return;
+  scr_str_release(rl->prompt);
+  rl->prompt = rl->old_prompt;
+  rl->old_prompt = NULL;
+  if (rl->prompt_value) scr_dyn_release(rl->prompt_value);
+  rl->prompt_value = rl->old_prompt_value;
+  rl->old_prompt_value = NULL;
 }
 
 /* ── close ─────────────────────────────────────────────────────────── */
@@ -251,11 +268,7 @@ void scr_rl_on_line(ScrRl *rl, ScrStr *line) {
     ScrClosure *cb = rl->q_cb;
     ScrRlLineFn fn = rl->q_fn;
     rl->q_cb = NULL;
-    if (rl->old_prompt) {
-      scr_str_release(rl->prompt);
-      rl->prompt = rl->old_prompt;
-      rl->old_prompt = NULL;
-    }
+    scr_rl_restore_prompt(rl);
     fn(cb, line);
     scr_closure_release(cb);
     return;
@@ -619,6 +632,8 @@ static void scr_rl_cleanup_atexit(void) {
     if (rl->out) rl->io->release(rl->out);
     scr_str_release(rl->prompt);
     if (rl->old_prompt) scr_str_release(rl->old_prompt);
+    if (rl->prompt_value) scr_dyn_release(rl->prompt_value);
+    if (rl->old_prompt_value) scr_dyn_release(rl->old_prompt_value);
     free(rl->line_buf);
     free(rl->parked);
     free(rl);
@@ -748,7 +763,58 @@ void scr_rl_question(double id, ScrStr *query, ScrClosure *cb /*moves*/, ScrRlLi
     return;
   }
   rl->old_prompt = rl->prompt;
+  rl->old_prompt_value = rl->prompt_value;
   rl->prompt = scr_str_retain(query);
+  rl->prompt_value = NULL;
+  rl->q_cb = cb;
+  rl->q_fn = fn;
+  scr_rl_prompt_now(rl);
+}
+
+/* A prompt that is not a string: String(value) for a primitive, which is
+ * what the terminal's line refresh and getCursorPos concatenate. An
+ * object's valueOf/toString would run on every refresh, and a symbol
+ * throws there, so a terminal interface refuses them (false, the refusal
+ * pending); another interface only writes the prompt, which throws for
+ * any value that is not a string, so it keeps ''. +1. */
+static bool scr_rl_prompt_text(ScrRl *rl, ScrDyn *value, ScrStr **out) {
+  if (scr_rl_primitive_prompt(value)) {
+    *out = scr_dyn_string_coerce(value);
+    return true;
+  }
+  if (!rl->tty) {
+    *out = scr_str_new("", 0);
+    return true;
+  }
+  static const char m[] =
+      "a terminal readline prompt that is an object or a symbol has no lowering";
+  scr_throw_error_msg_code(SCR_ERR_ERROR, m, sizeof m - 1, "SC2020");
+  return false;
+}
+
+/* question(query, cb) with a checked-dynamic query: a string goes through
+ * scr_rl_question. Another value becomes the prompt, the callback is
+ * kept, and the prompt write throws ERR_INVALID_ARG_TYPE on an interface
+ * that is not a terminal (the question stays pending, as in Node). */
+void scr_rl_question_dyn(double id, ScrDyn *query, ScrClosure *cb /*moves*/, ScrRlLineFn fn) {
+  if (query->kind == SCR_DYN_STR) {
+    scr_rl_question(id, query->v.str, cb, fn);
+    return;
+  }
+  ScrRl *rl = scr_rl_find(id);
+  if (!rl || rl->closed || rl->q_cb) {
+    scr_rl_question(id, NULL, cb, fn); /* the closed throw, or the re-prompt */
+    return;
+  }
+  ScrStr *text;
+  if (!scr_rl_prompt_text(rl, query, &text)) {
+    scr_closure_release(cb);
+    return;
+  }
+  rl->old_prompt = rl->prompt;
+  rl->old_prompt_value = rl->prompt_value;
+  rl->prompt = text;
+  rl->prompt_value = scr_dyn_retain(query);
   rl->q_cb = cb;
   rl->q_fn = fn;
   scr_rl_prompt_now(rl);
@@ -857,11 +923,7 @@ static ScrDyn *scr_rl_ask_abort_thunk(ScrClosure *clo, ScrDyn *const *args, size
   if (rl && rl->q_cb) {
     scr_closure_release(rl->q_cb);
     rl->q_cb = NULL;
-    if (rl->old_prompt) {
-      scr_str_release(rl->prompt);
-      rl->prompt = rl->old_prompt;
-      rl->old_prompt = NULL;
-    }
+    scr_rl_restore_prompt(rl);
     if (rl->tty) {
       scr_rl_tty_ops->clear_line(rl);
     } else {
@@ -877,8 +939,11 @@ static ScrDyn *scr_rl_ask_abort_thunk(ScrClosure *clo, ScrDyn *const *args, size
 
 /* readline/promises question(query, { signal }): rejects with
  * ERR_USE_AFTER_CLOSE on a closed interface and with an AbortError when
- * the signal is (or becomes) aborted. */
-ScrPromise *scr_rl_question_promise(double id, ScrStr *query, ScrDyn *signal, ScrAbortAddFn add) {
+ * the signal is (or becomes) aborted. A checked-dynamic query (query_dyn,
+ * query NULL) that is not a string rejects with what question() throws,
+ * as Node's promise executor does. */
+static ScrPromise *scr_rl_ask(double id, ScrStr *query, ScrDyn *query_dyn, ScrDyn *signal,
+                              ScrAbortAddFn add) {
   RlAsk *a = calloc(1, sizeof *a);
   if (!a) scr_rl_oom();
   a->rc = 1;
@@ -928,10 +993,29 @@ ScrPromise *scr_rl_question_promise(double id, ScrStr *query, ScrDyn *signal, Sc
   scr_box_set_ref(cb->caps[0], a); /* the creation reference moves here */
   cb->caps[1] = scr_box_new_obj(&scr_rl_dyn_retain_v, &scr_rl_dyn_release_v, NULL);
   scr_box_set_ref(cb->caps[1], dispose); /* moves (NULL without a signal) */
-  scr_rl_question(id, query, cb, &scr_rl_ask_answer);
+  if (!query_dyn) {
+    scr_rl_question(id, query, cb, &scr_rl_ask_answer);
+    return result;
+  }
+  scr_rl_ask_retain_v(a);
+  scr_rl_question_dyn(id, query_dyn, cb, &scr_rl_ask_answer);
+  if (scr_exc_pending() && !a->settled) {
+    a->settled = true;
+    scr_promise_reject_pending(a->p);
+  }
+  scr_rl_ask_release_v(a);
   return result;
 }
 
+ScrPromise *scr_rl_question_promise(double id, ScrStr *query, ScrDyn *signal, ScrAbortAddFn add) {
+  return scr_rl_ask(id, query, NULL, signal, add);
+}
+
+ScrPromise *scr_rl_question_promise_dyn(double id, ScrDyn *query, ScrDyn *signal,
+                                        ScrAbortAddFn add) {
+  return scr_rl_ask(id, NULL, query, signal, add);
+}
+
 void scr_rl_close(double id) {
   ScrRl *rl = scr_rl_find(id);
   if (rl) scr_rl_settle_close(rl); /* twice is a no-op, like Node */
@@ -985,13 +1069,48 @@ void scr_rl_set_prompt(double id, ScrStr *prompt) {
   if (!rl) return;
   scr_str_release(rl->prompt);
   rl->prompt = scr_str_retain(prompt);
+  if (rl->prompt_value) scr_dyn_release(rl->prompt_value);
+  rl->prompt_value = NULL;
+}
+
+/* setPrompt(value) with a checked-dynamic value; borrows. */
+void scr_rl_set_prompt_dyn(double id, ScrDyn *prompt) {
+  if (prompt->kind == SCR_DYN_STR) {
+    scr_rl_set_prompt(id, prompt->v.str);
+    return;
+  }
+  ScrRl *rl = scr_rl_find(id);
+  if (!rl) return;
+  ScrStr *text;
+  if (!scr_rl_prompt_text(rl, prompt, &text)) return;
+  scr_str_release(rl->prompt);
+  rl->prompt = text;
+  if (rl->prompt_value) scr_dyn_release(rl->prompt_value);
+  rl->prompt_value = scr_dyn_retain(prompt);
 }
 
 ScrStr *scr_rl_get_prompt(double id) {
   ScrRl *rl = scr_rl_find(id);
+  if (rl && rl->prompt_value) {
+    static const char m[] = "rl.getPrompt() of a prompt that is not a string has no lowering";
+    scr_throw_error_msg_code(SCR_ERR_ERROR, m, sizeof m - 1, "SC2020");
+    return scr_str_new("", 0);
+  }
   return rl ? scr_str_retain(rl->prompt) : scr_str_new("", 0);
 }
 
+/* Called after a node:readline/promises interface opens: its Interface
+ * class is not node:readline's, which instanceof tells apart. */
+void scr_rl_mark_promises(double id) {
+  ScrRl *rl = scr_rl_find(id);
+  if (rl) rl->promises = true;
+}
+
+bool scr_rl_is_promises(double id) {
+  ScrRl *rl = scr_rl_find(id);
+  return rl && rl->promises;
+}
+
 bool scr_rl_is_terminal(double id) {
   ScrRl *rl = scr_rl_find(id);
   return rl && rl->tty;
diff --git a/packages/runtime/src/scr_readline.h b/packages/runtime/src/scr_readline.h
index 9385f6dd7..4557dcb4d 100644
--- a/packages/runtime/src/scr_readline.h
+++ b/packages/runtime/src/scr_readline.h
@@ -47,13 +47,22 @@ void scr_rl_input_error(double id, ScrError *err);
 void scr_rl_question(double id, ScrStr *query, ScrClosure *cb /*moves*/,
                       void (*fn)(ScrClosure *, ScrStr *));
 ScrPromise *scr_rl_question_promise(double id, ScrStr *query, ScrDyn *signal, ScrAbortAddFn add);
+/* The same with a checked-dynamic query (borrowed). A query that is not a
+ * string makes the prompt write throw ERR_INVALID_ARG_TYPE (the promise
+ * form rejects with it) unless the interface is a terminal; the question
+ * stays pending, as in Node. */
+void scr_rl_question_dyn(double id, ScrDyn *query, ScrClosure *cb /*moves*/,
+                         void (*fn)(ScrClosure *, ScrStr *));
+ScrPromise *scr_rl_question_promise_dyn(double id, ScrDyn *query, ScrDyn *signal,
+                                        ScrAbortAddFn add);
 void scr_rl_close(double id);
 void scr_rl_pause(double id);  /* may throw ERR_USE_AFTER_CLOSE */
 void scr_rl_resume(double id); /* may throw ERR_USE_AFTER_CLOSE */
 void scr_rl_prompt(double id); /* may throw ERR_USE_AFTER_CLOSE */
 void scr_rl_prompt_with(double id, bool preserve); /* prompt(preserveCursor); may throw */
 void scr_rl_set_prompt(double id, ScrStr *prompt);
-ScrStr *scr_rl_get_prompt(double id); /* +1 */
+void scr_rl_set_prompt_dyn(double id, ScrDyn *prompt); /* borrows; may throw */
+ScrStr *scr_rl_get_prompt(double id); /* +1; may throw (a prompt that is not a string) */
 void scr_rl_write(double id, ScrStr *data); /* may throw ERR_USE_AFTER_CLOSE */
 void scr_rl_on(double id, double ev, ScrClosure *cb /*moves*/, void *fn, bool once);
 /* createInterface's history and editing options, in Node's order: the
@@ -83,6 +92,8 @@ double scr_rl_num_prop(double id, double which);
  * when there is a completer (the inspect unit links only then). */
 void scr_rl_terminal(double id, double mode, bool on, ScrDyn *completer, bool promises,
                      ScrStr *(*inspect)(ScrDyn *, double, double));
+void scr_rl_mark_promises(double id);
+bool scr_rl_is_promises(double id);
 bool scr_rl_is_terminal(double id);
 /* readline.cursorTo / moveCursor / clearLine / clearScreenDown: the data
  * written (+1; kind 0-3), after the argument checks (may throw), and
@@ -135,6 +146,9 @@ void scr_rl_error_thunk_dyn(ScrClosure *cb, ScrError *err);
  * the input stream or NULL for process.stdin; out the output stream or
  * NULL (out_stdout picks process.stdout). Both borrowed, like prompt
  * (NULL: the default "> "). */
+/* A checked-dynamic input or output as its stream (+1; NULL for an output
+ * of null or undefined); refuses other values (may throw). */
+ScrStream *scr_stream_rl_from_dyn(const ScrDyn *value, bool output);
 double scr_stream_rl_open(ScrStream *in, ScrStream *out, bool out_stdout, double crlf_delay,
                           ScrStr *prompt, ScrDyn *signal, ScrAbortAddFn add);
 void scr_stdin_data_thunk0(ScrClosure *cb, ScrBytes *chunk);
diff --git a/packages/runtime/src/scr_readline_internal.h b/packages/runtime/src/scr_readline_internal.h
index 0fe2e2cb2..49ef42f39 100644
--- a/packages/runtime/src/scr_readline_internal.h
+++ b/packages/runtime/src/scr_readline_internal.h
@@ -56,11 +56,17 @@ typedef struct ScrRl {
   bool stdin_in; /* reads process.stdin through the shared consumer */
   bool dead;     /* stdin only: created after stdin ended */
   bool paused;
+  bool promises; /* created by node:readline/promises */
   const ScrRlIo *io; /* the stream side, for a stream input or output */
   void *in;  /* the input stream (+1), or NULL */
   void *out; /* the output stream (+1), or NULL */
   bool out_stdout;
   ScrStr *prompt, *old_prompt;
+  /* A prompt that is not a string (setPrompt or question with another
+   * value), +1, or NULL; prompt then holds String(value) for a terminal
+   * interface. Writing it the way Node's kWriteToOutput does throws
+   * ERR_INVALID_ARG_TYPE. old_prompt_value is old_prompt's. */
+  ScrDyn *prompt_value, *old_prompt_value;
   ScrClosure *q_cb; /* the pending question's callback (owned) */
   ScrRlLineFn q_fn;
   /* the last promise question (kQuestionReject), which the terminal's
@@ -114,6 +120,14 @@ ScrArr *scr_rl_history_of(ScrRl *rl); /* borrowed; created on first use */
 void scr_rl_emit(ScrRl *rl, int ev, ScrStr *line, ScrError *err);
 void scr_rl_emit_history(ScrRl *rl);
 void scr_rl_write_out(ScrRl *rl, ScrStr *text);
+/* kWriteToOutput(prompt)'s validateString: false with ERR_INVALID_ARG_TYPE
+ * pending when the prompt is not a string. */
+bool scr_rl_prompt_writable(ScrRl *rl);
+/* A prompt value whose String() the interface keeps in prompt. */
+static inline bool scr_rl_primitive_prompt(const ScrDyn *v) {
+  return v->kind == SCR_DYN_NULL || v->kind == SCR_DYN_UNDEF || v->kind == SCR_DYN_BOOL ||
+         v->kind == SCR_DYN_NUM || v->kind == SCR_DYN_BIGINT;
+}
 /* kOnLine: a pending question takes the line, else 'line'. Moves line. */
 void scr_rl_on_line(ScrRl *rl, ScrStr *line);
 void scr_rl_do_pause(ScrRl *rl);
diff --git a/packages/runtime/src/scr_readline_tty.c b/packages/runtime/src/scr_readline_tty.c
index 38271411f..1c5fcd5f6 100644
--- a/packages/runtime/src/scr_readline_tty.c
+++ b/packages/runtime/src/scr_readline_tty.c
@@ -2255,7 +2255,7 @@ static void tty_prompt(ScrRl *rl, bool preserve) {
   bool dumb = term && term->len == 4 && memcmp(term->data, "dumb", 4) == 0;
   if (term) scr_str_release(term);
   if (dumb) {
-    scr_rl_write_out(rl, rl->prompt);
+    if (scr_rl_prompt_writable(rl)) scr_rl_write_out(rl, rl->prompt);
     return;
   }
   if (!preserve) t->cursor = 0;
@@ -2333,6 +2333,12 @@ double scr_rl_cursor_pos(double id, double which) {
   if (rl->tty) {
     pos = tty_cursor_pos(rl);
   } else {
+    if (rl->prompt_value && !scr_rl_primitive_prompt(rl->prompt_value)) {
+      static const char m[] =
+          "rl.getCursorPos() with a prompt that is an object or a symbol has no lowering";
+      scr_throw_error_msg_code(SCR_ERR_ERROR, m, sizeof m - 1, "SC2020");
+      return 0;
+    }
     ScrRlTty probe = {0};
     probe.columns = INFINITY;
     rl->tty = &probe;
diff --git a/packages/runtime/src/scr_stream.c b/packages/runtime/src/scr_stream.c
index c2d27e7ce..5f0bb493d 100644
--- a/packages/runtime/src/scr_stream.c
+++ b/packages/runtime/src/scr_stream.c
@@ -4728,6 +4728,31 @@ static void scr_stream_rl_hooks_free(void) {
   }
 }
 
+/* createInterface's input or output given as a checked-dynamic value (a
+ * JavaScript function's result, an object's member): the stream (+1).
+ * An output of null or undefined is NULL (no output). A value that is
+ * not a stream with a readable (input) or writable (output) side is
+ * refused. */
+ScrStream *scr_stream_rl_from_dyn(const ScrDyn *value, bool output) {
+  if (output && (value->kind == SCR_DYN_NULL || value->kind == SCR_DYN_UNDEF)) return NULL;
+  if (value->kind == SCR_DYN_TYPED_REF && value->v.typed_ref.type_key_len > 7 &&
+      !memcmp(value->v.typed_ref.type_key, "object:", 7)) {
+    ScrStream *stream = scr_dyn_typed_ref_unbox(value);
+    const ScrVt *vt = stream->vt;
+    bool duplex = vt == &scr_duplex_vt || vt == &scr_transform_vt || vt == &scr_passthrough_vt ||
+                  scr_vt_within(vt, &scr_duplex_vt);
+    bool ok = duplex || (output ? vt == &scr_writable_vt || scr_vt_within(vt, &scr_writable_vt)
+                                : vt == &scr_readable_vt || scr_vt_within(vt, &scr_readable_vt));
+    if (ok) return stream;
+    value->v.typed_ref.release(stream);
+  }
+  static const char in_m[] = "createInterface with an input that is not a readable stream has no lowering";
+  static const char out_m[] = "createInterface with an output that is not a writable stream has no lowering";
+  if (output) scr_throw_error_msg_code(SCR_ERR_ERROR, out_m, sizeof out_m - 1, "SC2020");
+  else scr_throw_error_msg_code(SCR_ERR_ERROR, in_m, sizeof in_m - 1, "SC2020");
+  return NULL;
+}
+
 double scr_stream_rl_open(ScrStream *in, ScrStream *out, bool out_stdout, double crlf_delay,
                           ScrStr *prompt, ScrDyn *signal, ScrAbortAddFn add) {
   double id = scr_rl_open(&scr_stream_rl_io, in ? scr_stream_retain(in) : NULL,
diff --git a/tests/corpus/5876-readline-dispose-instanceof.ts b/tests/corpus/5876-readline-dispose-instanceof.ts
new file mode 100644
index 000000000..63f058e9b
--- /dev/null
+++ b/tests/corpus/5876-readline-dispose-instanceof.ts
@@ -0,0 +1,28 @@
+// rl[Symbol.dispose]() closes the interface as close() does, and a second
+// call does nothing. instanceof tells node:readline's Interface from
+// node:readline/promises' one.
+import * as readline from "node:readline";
+import * as readlinePromises from "node:readline/promises";
+import { PassThrough } from "node:stream";
+
+const rl = readline.createInterface({ input: new PassThrough() });
+rl.on("close", () => console.log("close 1"));
+rl[Symbol.dispose]();
+console.log("disposed");
+rl[Symbol.dispose]();
+rl.close();
+console.log("after second dispose");
+
+const prl = readlinePromises.createInterface({ input: new PassThrough() });
+prl.on("close", () => console.log("close 2"));
+console.log(rl instanceof readline.Interface, rl instanceof readlinePromises.Interface);
+console.log(prl instanceof readline.Interface, prl instanceof readlinePromises.Interface);
+prl[Symbol.dispose]();
+
+function make(): readline.Interface {
+  return readline.createInterface({ input: new PassThrough() });
+}
+const made = make();
+made.on("close", () => console.log("close 3"));
+made[Symbol.dispose]();
+console.log("done");
diff --git a/tests/corpus/5877-readline-question-query.cjs b/tests/corpus/5877-readline-question-query.cjs
new file mode 100644
index 000000000..734311b16
--- /dev/null
+++ b/tests/corpus/5877-readline-question-query.cjs
@@ -0,0 +1,51 @@
+// question() with a query that is not a string: a non-terminal interface
+// throws (callback form) or rejects (readline/promises) with Node's
+// ERR_INVALID_ARG_TYPE from the output write, and the question stays
+// pending; a terminal interface writes the query as a string.
+const readline = require("readline");
+const readlinePromises = require("readline/promises");
+const { PassThrough } = require("stream");
+
+function capture(name) {
+  const output = new PassThrough();
+  output.on("data", (d) => console.log(name, JSON.stringify(String(d))));
+  return output;
+}
+
+async function main() {
+  const input = new PassThrough();
+  const rl = readline.createInterface({ input, output: capture("out") });
+  rl.on("line", (line) => console.log("line", line));
+  try {
+    rl.question(42, (answer) => console.log("answer", answer));
+  } catch (e) {
+    console.log(e.name, e.code, e.message);
+  }
+  try {
+    rl.prompt();
+  } catch (e) {
+    console.log("prompt", e.code, e.message);
+  }
+  input.write("first\nsecond\n");
+  await new Promise((resolve) => setImmediate(resolve));
+  console.log("prompt after", JSON.stringify(rl.getPrompt()));
+  rl.close();
+
+  for (const query of [undefined, null, { a: 1 }, [1, 2], true]) {
+    const prl = readlinePromises.createInterface({ input: new PassThrough() });
+    try {
+      await prl.question(query);
+    } catch (e) {
+      console.log("rejected", e.code, e.message);
+    }
+    prl.close();
+  }
+
+  const tin = new PassThrough();
+  const trl = readline.createInterface({ input: tin, output: capture("tty"), terminal: true });
+  trl.question(7, (answer) => console.log("tty answer", answer));
+  tin.write("x\r");
+  await new Promise((resolve) => setImmediate(resolve));
+  trl.close();
+}
+main();
diff --git a/tests/corpus/5878-readline-dynamic-streams.mjs b/tests/corpus/5878-readline-dynamic-streams.mjs
new file mode 100644
index 000000000..b1b9f4ee5
--- /dev/null
+++ b/tests/corpus/5878-readline-dynamic-streams.mjs
@@ -0,0 +1,41 @@
+// createInterface over an input or output that is a function's result,
+// an object's member or an array element.
+import * as readline from "node:readline";
+import * as readlinePromises from "node:readline/promises";
+import { PassThrough, Readable, Writable } from "node:stream";
+
+function source(lines) {
+  return Readable.from([lines.join("\n") + "\n"]);
+}
+const streams = { input: source(["a", "b"]), output: new PassThrough() };
+streams.output.on("data", (d) => console.log("out", JSON.stringify(String(d))));
+
+const rl1 = readline.createInterface({ input: source(["one", "two"]) });
+for await (const line of rl1) console.log("rl1", line);
+
+const rl2 = readline.createInterface({ input: streams.input, output: streams.output, prompt: "? " });
+rl2.prompt();
+for await (const line of rl2) console.log("rl2", line);
+
+const inputs = [source(["x"]), source(["y"])];
+for (const [i, input] of inputs.entries()) {
+  const rl = readline.createInterface(input);
+  rl.on("line", (line) => console.log("rl3", i, line));
+  await new Promise((resolve) => {
+    rl.on("close", () => resolve(undefined));
+  });
+}
+
+const sink = new Writable({
+  write(chunk, _encoding, callback) {
+    console.log("sink", JSON.stringify(String(chunk)));
+    callback();
+  },
+});
+const make = () => ({ input: new PassThrough(), output: sink });
+const opts = make();
+const prl = readlinePromises.createInterface(opts.input, opts.output);
+const answer = prl.question("name? ");
+opts.input.write("ada\n");
+console.log("answer", await answer);
+prl.close();
diff --git a/tests/harness/corpus-costs.json b/tests/harness/corpus-costs.json
index 30899d72b..b18e2ab28 100644
--- a/tests/harness/corpus-costs.json
+++ b/tests/harness/corpus-costs.json
@@ -2129,6 +2129,9 @@
     "5873-readline-promises-namespace.cjs": 2023,
     "5874-worker-stdio-streams.ts": 2839,
     "5875-worker-stdout-pipe.cjs": 2740,
+    "5876-readline-dispose-instanceof.ts": 2465,
+    "5877-readline-question-query.cjs": 3233,
+    "5878-readline-dynamic-streams.mjs": 2925,
     "5879-worker-stdin.ts": 3158,
     "5880-emitter-leak-warning-delivery.ts": 3418,
     "5881-inspect-weak-collections.ts": 2615,
@@ -5223,6 +5226,9 @@
     "5873-readline-promises-namespace.cjs": 3811,
     "5874-worker-stdio-streams.ts": 27801,
     "5875-worker-stdout-pipe.cjs": 31391,
+    "5876-readline-dispose-instanceof.ts": 29361,
+    "5877-readline-question-query.cjs": 170940,
+    "5878-readline-dynamic-streams.mjs": 25503,
     "5879-worker-stdin.ts": 33232,
     "5880-emitter-leak-warning-delivery.ts": 4319,
     "5881-inspect-weak-collections.ts": 2915,