fix(action): allow forward sync from trailer commits

docs/adr/005-git-trailer-loop-prevention.md

@@ -17,7 +17,7 @@ Bidirectional sync creates an infinite loop risk: forward sync pushes commit A t
 
 ## Decision
 
-All bot commits include a git trailer with a configurable key (default: `Josh-Sync-Origin`). Both sync directions filter out commits containing this trailer.
+All bot commits include a git trailer with a configurable key (default: `Josh-Sync-Origin`). Reverse sync filters out commits containing this trailer so bot-generated forward-sync commits are not proposed back to the monorepo.
 
 ### Format
 
@@ -32,7 +32,7 @@ The trailer value encodes: direction, branch, and timestamp. This aids debugging
 ### Filtering
 
 - **Reverse sync**: `git log --invert-grep --grep="^${BOT_TRAILER}:"` excludes all commits with the trailer
-- **CI loop guard**: The composite action checks if HEAD commit has the trailer before running sync at all
+- **Forward sync**: the composite action still runs even when HEAD has the trailer; forward sync uses tree comparison, sync state, and merge checks to decide whether to push
 
 ### Configuration
 
@@ -44,7 +44,7 @@ The trailer key is set in `.josh-sync.yml` under `bot.trailer`. This allows mult
 - Reliable loop prevention — trailer is part of the immutable commit object
 - Configurable key avoids conflicts between multiple sync bots
 - Human-readable — `git log` shows the trailer in commit messages
-- CI loop guard prevents unnecessary sync runs entirely
+- Repositories can act as middle hops, receiving a sync commit from one relationship and forwarding relevant changes to another
 
 **Negative:**
 - Commits with manually-added trailers matching the key would be incorrectly filtered