diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 54c9e2109..6cb61196e 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -4,7 +4,7 @@
 
 ### Fixed
 
-- Narrowed the `history://` contract in the system prompt to match the implementation: it serves agents in the current session's tree (including their persisted unregistered/released/resumed subagents), not independent top-level OMP sessions whose files persist under the same session directory ([#5839](https://github.com/can1357/oh-my-pi/issues/5839)).
+- Narrowed the `history://` contract in the system prompt to match the implementation: it serves registered agents process-wide plus persisted subagents discoverable from their artifact trees, but does not discover unregistered top-level sessions solely from persisted session files ([#5839](https://github.com/can1357/oh-my-pi/issues/5839)).
 
 ## [17.0.2] - 2026-07-17
 
diff --git a/packages/coding-agent/src/prompts/system/system-prompt.md b/packages/coding-agent/src/prompts/system/system-prompt.md
index 7ef8431be..2fea8f221 100644
--- a/packages/coding-agent/src/prompts/system/system-prompt.md
+++ b/packages/coding-agent/src/prompts/system/system-prompt.md
@@ -57,7 +57,7 @@ Special URLs for internal resources; with most FS/bash tools they auto-resolve t
 - `memory://root`: project memory summary
   {{/if}}
 - `agent://<id>`: agent output artifact; `/<child>` reads a nested subagent's output, else `/<path>` extracts a JSON field
-- `history://<id>`: read-only markdown transcript of an agent (live, parked, or released); bare `history://` lists all agents. Serves agents in the current session's tree, including their persisted subagents whose files remain on disk (unregistered, released, or resumed) — not independent top-level OMP sessions.
+- `history://<id>`: read-only markdown transcript of an agent (live, parked, or released); bare `history://` lists all agents. Serves registered agents process-wide plus persisted subagents discoverable from their artifact trees; does not discover unregistered top-level sessions solely from their persisted session files.
 - `artifact://<id>`: artifact content
 - `local://<name>.md`: plan artifacts or shared content for subagents
 {{#if hasObsidian}}