[SILENT] internal cron marker uses substring matching → user paste can trigger silent message loss

Severity: Low
Category: Kernel orchestration logic
Labels: bug, low

Affected files

• crates/librefang-kernel/src/kernel/agent_execution.rs:889-892, 1102

Description

if message.contains("[SILENT]") { ... }

uses a substring match against free-form user text. Real users pasting content that happens to contain a literal [SILENT] (log snippets, translation tables, internal-doc copy-paste) all trigger:

• :890 skips the LLM-side payload mutation;
• :1102 skips persistence;
• and that user turn vanishes silently.

Recommendation

Introduce a structured marker instead of a string check:

// add a field to SenderContext
pub struct SenderContext {
    ...
    pub silent: bool,
}

As a less-invasive alternative: restrict the check to is_internal_cron && message.starts_with("[SILENT]") (prefix rather than arbitrary position), and prepend a control-character prefix that user paste can never produce.