diff --git a/src/dispatch.rs b/src/dispatch.rs
new file mode 100644
index 0000000..512558c
--- /dev/null
+++ b/src/dispatch.rs
@@ -0,0 +1,77 @@
+//! Text-level codec dispatch: parse a harness's native session text into the
+//! canonical model, or render the canonical model back to native text, keyed
+//! by a runtime [`HarnessId`].
+//!
+//! No filesystem, no `SQLite`, no subprocess: this is the codec layer alone
+//! (see [`TextCodec`]), so it is available on every target, WASM included. The
+//! WASM bindings and [`fidelity`](crate::fidelity) both route through it.
+
+use crate::harness::{
+    amp, antigravity, campfire, chatgpt, claude_chat, claude_code, codex, cowork, cowork_remote,
+    cursor, cursor_desktop, fx, grok, grok_bot, hermes, opencode, pi, simple,
+};
+use crate::transcript::{Codec, Common, HarnessId, TextCodec, Transcript};
+
+/// Parse `harness`'s native session text into the canonical model.
+///
+/// # Errors
+/// When the text is not that harness's session format.
+pub fn parse_to_common(harness: HarnessId, text: &str) -> crate::Result<Transcript<Common>> {
+    fn go<H: TextCodec + Codec>(text: &str) -> crate::Result<Transcript<Common>> {
+        H::to_common(&H::from_text(text)?)
+    }
+    match harness {
+        HarnessId::ClaudeCode => go::<claude_code::ClaudeCode>(text),
+        HarnessId::ClaudeChat => go::<claude_chat::ClaudeChat>(text),
+        HarnessId::CoworkRemote => go::<cowork_remote::CoworkRemote>(text),
+        HarnessId::ChatGpt => go::<chatgpt::ChatGpt>(text),
+        HarnessId::Codex => go::<codex::Codex>(text),
+        HarnessId::OpenCode => go::<opencode::OpenCode>(text),
+        HarnessId::Pi => go::<pi::Pi>(text),
+        HarnessId::Campfire => go::<campfire::Campfire>(text),
+        HarnessId::Cursor => go::<cursor::Cursor>(text),
+        HarnessId::CursorDesktop => go::<cursor_desktop::CursorDesktop>(text),
+        HarnessId::Grok => go::<grok::Grok>(text),
+        HarnessId::GrokBot => go::<grok_bot::GrokBot>(text),
+        HarnessId::Fx => go::<fx::Fx>(text),
+        HarnessId::Hermes => go::<hermes::Hermes>(text),
+        HarnessId::Amp => go::<amp::Amp>(text),
+        HarnessId::Antigravity => go::<antigravity::Antigravity>(text),
+        HarnessId::Simple => go::<simple::Simple>(text),
+        HarnessId::Cowork => go::<cowork::Cowork>(text),
+    }
+}
+
+/// Render the canonical model as `harness`'s native session text.
+///
+/// # Errors
+/// When the harness cannot represent the transcript (the live read-only
+/// sources, for one).
+pub fn render_from_common(
+    harness: HarnessId,
+    common: &Transcript<Common>,
+) -> crate::Result<String> {
+    fn go<H: TextCodec + Codec>(common: &Transcript<Common>) -> crate::Result<String> {
+        H::to_text(&H::from_common(common)?)
+    }
+    match harness {
+        HarnessId::ClaudeCode => go::<claude_code::ClaudeCode>(common),
+        HarnessId::ClaudeChat => go::<claude_chat::ClaudeChat>(common),
+        HarnessId::CoworkRemote => go::<cowork_remote::CoworkRemote>(common),
+        HarnessId::ChatGpt => go::<chatgpt::ChatGpt>(common),
+        HarnessId::Codex => go::<codex::Codex>(common),
+        HarnessId::OpenCode => go::<opencode::OpenCode>(common),
+        HarnessId::Pi => go::<pi::Pi>(common),
+        HarnessId::Campfire => go::<campfire::Campfire>(common),
+        HarnessId::Cursor => go::<cursor::Cursor>(common),
+        HarnessId::CursorDesktop => go::<cursor_desktop::CursorDesktop>(common),
+        HarnessId::Grok => go::<grok::Grok>(common),
+        HarnessId::GrokBot => go::<grok_bot::GrokBot>(common),
+        HarnessId::Fx => go::<fx::Fx>(common),
+        HarnessId::Hermes => go::<hermes::Hermes>(common),
+        HarnessId::Amp => go::<amp::Amp>(common),
+        HarnessId::Antigravity => go::<antigravity::Antigravity>(common),
+        HarnessId::Simple => go::<simple::Simple>(common),
+        HarnessId::Cowork => go::<cowork::Cowork>(common),
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index a340523..3dd58da 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -17,8 +17,11 @@
 //! - [`Transcript`], [`Harness`], [`Codec`], [`Store`] — the generic type and
 //!   the traits over it.
 //! - [`harness`] — one module per implemented harness.
+//! - [`dispatch`] — parse or render a harness's native text, chosen by
+//!   [`HarnessId`] at run time.
 
 pub mod common;
+pub mod dispatch;
 pub mod error;
 pub mod harness;
 #[cfg(not(target_arch = "wasm32"))]
diff --git a/src/wasm.rs b/src/wasm.rs
index e1bbb6f..2417b07 100644
--- a/src/wasm.rs
+++ b/src/wasm.rs
@@ -13,11 +13,8 @@ use serde::{Deserialize, Serialize};
 use wasm_bindgen::prelude::*;
 
 use crate::common;
-use crate::harness::{
-    amp, antigravity, campfire, chatgpt, claude_chat, claude_code, codex, cowork, cowork_remote,
-    cursor, cursor_desktop, fx, grok, grok_bot, hermes, opencode, pi, simple,
-};
-use crate::transcript::{Codec, Common, HarnessId, TextCodec, Transcript};
+use crate::dispatch::{parse_to_common, render_from_common};
+use crate::transcript::{HarnessId, Transcript};
 
 /// Continue/convert a session from one harness's native text into another's.
 ///
@@ -194,58 +191,6 @@ struct CommonJson {
     messages: Vec<common::Message>,
 }
 
-fn parse_to_common(harness: HarnessId, text: &str) -> crate::Result<Transcript<Common>> {
-    fn go<H: TextCodec + Codec>(text: &str) -> crate::Result<Transcript<Common>> {
-        H::to_common(&H::from_text(text)?)
-    }
-    match harness {
-        HarnessId::ClaudeCode => go::<claude_code::ClaudeCode>(text),
-        HarnessId::ClaudeChat => go::<claude_chat::ClaudeChat>(text),
-        HarnessId::CoworkRemote => go::<cowork_remote::CoworkRemote>(text),
-        HarnessId::ChatGpt => go::<chatgpt::ChatGpt>(text),
-        HarnessId::Codex => go::<codex::Codex>(text),
-        HarnessId::OpenCode => go::<opencode::OpenCode>(text),
-        HarnessId::Pi => go::<pi::Pi>(text),
-        HarnessId::Campfire => go::<campfire::Campfire>(text),
-        HarnessId::Cursor => go::<cursor::Cursor>(text),
-        HarnessId::CursorDesktop => go::<cursor_desktop::CursorDesktop>(text),
-        HarnessId::Grok => go::<grok::Grok>(text),
-        HarnessId::GrokBot => go::<grok_bot::GrokBot>(text),
-        HarnessId::Fx => go::<fx::Fx>(text),
-        HarnessId::Hermes => go::<hermes::Hermes>(text),
-        HarnessId::Amp => go::<amp::Amp>(text),
-        HarnessId::Antigravity => go::<antigravity::Antigravity>(text),
-        HarnessId::Simple => go::<simple::Simple>(text),
-        HarnessId::Cowork => go::<cowork::Cowork>(text),
-    }
-}
-
-fn render_from_common(harness: HarnessId, common: &Transcript<Common>) -> crate::Result<String> {
-    fn go<H: TextCodec + Codec>(common: &Transcript<Common>) -> crate::Result<String> {
-        H::to_text(&H::from_common(common)?)
-    }
-    match harness {
-        HarnessId::ClaudeCode => go::<claude_code::ClaudeCode>(common),
-        HarnessId::ClaudeChat => go::<claude_chat::ClaudeChat>(common),
-        HarnessId::CoworkRemote => go::<cowork_remote::CoworkRemote>(common),
-        HarnessId::ChatGpt => go::<chatgpt::ChatGpt>(common),
-        HarnessId::Codex => go::<codex::Codex>(common),
-        HarnessId::OpenCode => go::<opencode::OpenCode>(common),
-        HarnessId::Pi => go::<pi::Pi>(common),
-        HarnessId::Campfire => go::<campfire::Campfire>(common),
-        HarnessId::Cursor => go::<cursor::Cursor>(common),
-        HarnessId::CursorDesktop => go::<cursor_desktop::CursorDesktop>(common),
-        HarnessId::Grok => go::<grok::Grok>(common),
-        HarnessId::GrokBot => go::<grok_bot::GrokBot>(common),
-        HarnessId::Fx => go::<fx::Fx>(common),
-        HarnessId::Hermes => go::<hermes::Hermes>(common),
-        HarnessId::Amp => go::<amp::Amp>(common),
-        HarnessId::Antigravity => go::<antigravity::Antigravity>(common),
-        HarnessId::Simple => go::<simple::Simple>(common),
-        HarnessId::Cowork => go::<cowork::Cowork>(common),
-    }
-}
-
 fn parse_harness(name: &str) -> Result<HarnessId, JsError> {
     name.parse().map_err(js)
 }