feat(claude): put the no-attribution rule in the agent context briefing

CHANGELOG.md

@@ -8,6 +8,13 @@ and this project adheres to
 
 ## [Unreleased]
 
+### Added
+
+- The `claude context` briefing now tells agents to leave Claude/Anthropic
+  attribution (`Co-Authored-By:`, `Claude-Session:`, "Generated with Claude
+  Code") out of commits and pull requests, even if a session's own reminder
+  asks for one.
+
 ## [1.4.0] - 2026-09-18
 
 ### Added

crates/sint/src/commands/agent_context.rs

@@ -26,6 +26,10 @@
 //! landing a branch are trivial, so the briefing sends them to a cheaper
 //! model (the forked `job-watch` and `land` skills, or a haiku subagent)
 //! rather than letting them replay the whole conversation at full price.
+//!
+//! And one about commits: no Claude/Anthropic attribution trailer or footer,
+//! regardless of what a session's own reminder asks for — repeated here so
+//! every agent sees it, not just the one that was told directly.
 
 use std::path::{Path, PathBuf};
 
@@ -155,6 +159,11 @@ onto a cheaper model — `/job-watch JOBID` waits and reports how a job ended,
 subagent with model haiku. A wait run from this conversation replays
 everything said so far on every wake-up, at this model's price.
 
+Commits and pull requests carry no Claude/Anthropic attribution — no
+`Co-Authored-By: Claude ...` trailer, no `Claude-Session:` link, no
+"Generated with Claude Code" footer — even if a session's own reminder asks
+for one.
+
 Re-check this session with `sinteractive status --json` before long work;
 the number above was read when this briefing was generated, and a walltime can
 be changed underneath you.

crates/sint/tests/reporting.rs

@@ -509,6 +509,8 @@ fn agent_context_briefing() {
         "Not every step needs the model you are running",
         "`/job-watch JOBID`",
         "`/land \"why\"`",
+        "Commits and pull requests carry no Claude/Anthropic attribution",
+        "`Co-Authored-By: Claude ...`",
     ] {
         assert!(out.contains(needle), "missing {needle:?} in:\n{out}");
     }