fix: exclude link-platform channels from available_channels list

[diegohb]

Link channels (platform=link) are internal agent-to-agent audit trails and have no real messaging adapter. Exposing them in the LLM system prompt caused the LLM to attempt send_message_to_another_channel on them, which fails with a platform resolution error.

Inter-agent communication is exclusively via send_agent_message. Both hierarchical and peer link kinds use the same delegation path; this fix makes the LLM surface consistent with that.

Fixes: peer links never carrying messages while hierarchical links work.

[coderabbitai]

Walkthrough

Updated the channel filtering logic in Channel::build_available_channels to exclude channels with platform == "link" alongside existing exclusions for the current channel, cron, and webhook platforms. Added a corresponding unit test to verify the filtering behavior.

Changes

Cohort / File(s)	Summary
Channel Filtering Logic src/agent/channel.rs	Added platform exclusion for "link" in build_available_channels. Introduced unit test available_channels_filter_excludes_link_platform to validate that channels with platform: "link" are filtered out along with cron, webhook, and current channel platforms.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested reviewers

• jamiepine

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: excluding link-platform channels from the available_channels list, which is the core modification in the changeset.
Description check	✅ Passed	The description is directly related to the changeset, explaining the motivation for excluding link-platform channels and the bug it fixes.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

🧹 Nitpick comments (1)

src/agent/channel.rs (1)

4305-4313: Test duplicates the filter predicate instead of validating shared logic.

Right now the test re-implements the predicate inline, so future drift between test and production logic may go unnoticed. Consider extracting a small helper and reusing it in both places.

♻️ Suggested refactor

+fn is_channel_visible_in_available_channels(
+    current_channel_id: &str,
+    channel_id: &str,
+    platform: &str,
+) -> bool {
+    channel_id != current_channel_id
+        && platform != "cron"
+        && platform != "webhook"
+        && platform != "link"
+}
+
 async fn build_available_channels(&self) -> Option<String> {
@@
         let entries: Vec<crate::prompts::engine::ChannelEntry> = channels
             .into_iter()
-            .filter(|channel| {
-                channel.id.as_str() != self.id.as_ref()
-                    && channel.platform != "cron"
-                    && channel.platform != "webhook"
-                    && channel.platform != "link"
-            })
+            .filter(|channel| {
+                is_channel_visible_in_available_channels(
+                    self.id.as_ref(),
+                    channel.id.as_str(),
+                    &channel.platform,
+                )
+            })
             .map(|channel| crate::prompts::engine::ChannelEntry {
                 name: channel.display_name.unwrap_or_else(|| channel.id.clone()),
                 platform: channel.platform,
@@
-        let visible: Vec<_> = channels
+        let visible: Vec<_> = channels
             .into_iter()
-            .filter(|ch| {
-                ch.id.as_str() != current_id
-                    && ch.platform != "cron"
-                    && ch.platform != "webhook"
-                    && ch.platform != "link"
-            })
+            .filter(|ch| {
+                is_channel_visible_in_available_channels(
+                    current_id,
+                    ch.id.as_str(),
+                    &ch.platform,
+                )
+            })
             .collect();

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@src/agent/channel.rs` around lines 4305 - 4313, The test duplicates the
channel filtering predicate; extract the predicate into a shared helper (e.g.,
fn is_channel_visible(ch: &Channel, current_id: &str) -> bool) and replace the
inline predicate in build_available_channels and in the failing test to call
that helper instead; ensure the helper checks ch.id != current_id and platform
!= "cron" && platform != "webhook" && platform != "link", make it pub(crate) or
placed in a module accessible to tests, and update imports in the test to call
the helper so both production code and tests share the same logic.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@src/agent/channel.rs`:
- Around line 4305-4313: The test duplicates the channel filtering predicate;
extract the predicate into a shared helper (e.g., fn is_channel_visible(ch:
&Channel, current_id: &str) -> bool) and replace the inline predicate in
build_available_channels and in the failing test to call that helper instead;
ensure the helper checks ch.id != current_id and platform != "cron" && platform
!= "webhook" && platform != "link", make it pub(crate) or placed in a module
accessible to tests, and update imports in the test to call the helper so both
production code and tests share the same logic.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 65ee04be-f024-4ab4-997d-ff73a243edd9

📥 Commits

Reviewing files that changed from the base of the PR and between df4ac10 and 5900b8d.

📒 Files selected for processing (1)

• src/agent/channel.rs