1 files changed, 85 insertions, 0 deletions
diff --git a/link/pi-merge.py b/link/pi-merge.py
new file mode 100644
index 0000000..1c2f822
--- /dev/null
+++ b/link/pi-merge.py
@@ -0,0 +1,85 @@
+"""Generate one of pi's JSON files from the repo and its fragments.
+
+    pi-merge.py <key> <base|-> <fragment dir> <target>
+
+Run by link/pi.sh, for ~/.pi/agent/models.json (key "providers") and
+~/.pi/agent/mcp.json (key "mcpServers"). It lives in a file rather than a
+heredoc inside $( ): macOS ships bash 3.2, which does not skip heredoc
+content when it scans for the end of a command substitution, so an odd
+number of apostrophes in here would stop the whole script parsing -- which
+it did, on 2026-09-25.
+"""
+
+import glob, json, os, sys
+
+merge_key, base_path, frag_dir, target = sys.argv[1:5]
+
+
+def load(path):
+    with open(path) as f:
+        return json.load(f)
+
+
+# The repo's file, if there is one, then each fragment's. A fragment may add an
+# entry under merge_key or replace one of the same name; any other top-level key
+# takes the last file's value. Which entry came from where is reported: a
+# fragment quietly shadowing one the repo ships would otherwise be invisible.
+# With no repo file every entry comes from a fragment, so only a replacement --
+# one fragment shadowing another's -- is worth a note.
+paths = sorted(glob.glob(os.path.join(frag_dir, "*.json")))
+if base_path != "-":
+    paths.insert(0, base_path)
+
+# A symlink is the pre-generation state: replace it, even with no fragments, so
+# the live file is never a tracked one.
+was_link = os.path.islink(target)
+
+# Nothing to generate from, and nothing there: leave it absent rather than
+# create an empty file.
+if not paths and not was_link and not os.path.exists(target):
+    print("unchanged:")
+    sys.exit(0)
+
+desired = {}
+notes = []
+for path in paths:
+    try:
+        layer = load(path)
+    except (OSError, ValueError) as e:
+        print("error:cannot read %s: %s" % (path, e))
+        sys.exit(0)
+    for key, value in layer.items():
+        if key == merge_key:
+            entries = desired.setdefault(merge_key, {})
+            if path != base_path:
+                for name in value:
+                    if base_path == "-" and name not in entries:
+                        continue
+                    notes.append("%s %s by %s" % (
+                        name,
+                        "replaced" if name in entries else "added",
+                        os.path.basename(path),
+                    ))
+            entries.update(value)
+        else:
+            desired[key] = value
+
+try:
+    current = None if was_link else load(target)
+except (OSError, ValueError):
+    current = None
+
+for note in notes:
+    print("note:" + note)
+
+if current == desired:
+    print("unchanged:")
+elif os.environ.get("DRY_RUN"):
+    print("would-write:" + ("replacing the link" if was_link else "merged changes"))
+else:
+    tmp = target + ".dotfiles-tmp"
+    with open(tmp, "w") as f:
+        json.dump(desired, f, indent=2)
+        f.write("\n")
+    os.replace(tmp, target)
+    print("wrote:" + ("replaced the link" if was_link else "merged changes"))