feat(identity): petname -- mesh-wide deterministic node label

src/macula_py/petname.py

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+"""Petnames: a deterministic, human-readable label for a mesh node id —
+Docker's adjective_color_animal convention with a four-digit suffix
+(e.g. "happy_green_rabbit_4831"). A pure function of the node id
+itself, not random per process: the same identity gets the same
+petname across restarts, across every tool that shows it, and on every
+other agent's roster too.
+
+The suffix exists because the mesh is expected to host THOUSANDS of
+agents: the word trio alone (64,000 combinations) collides visibly
+under the birthday problem at a few hundred identities; the trio plus
+a 4-digit hash group (640,000,000 combinations) stays effectively
+collision-free at fleet scale while remaining scannable.
+
+The word lists and derivation are shared verbatim with macula-mcp's
+petname.ts, macula-rust's petname() and macula-go's identity.Petname:
+same sha256 of the lowercased hex id, same 16-bit reads modulo the
+list lengths, plus the suffix group.
+"""
+
+import hashlib
+
+ADJECTIVES_A = [
+    "bold", "bouncy", "brave", "breezy", "calm", "cheerful", "clever", "curious",
+    "daring", "eager", "elegant", "fierce", "gentle", "graceful", "humble", "jolly",
+    "jovial", "keen", "kind", "lively", "lucky", "mellow", "merry", "nimble",
+    "noble", "plucky", "proud", "quiet", "quirky", "radiant", "silly", "sleepy",
+    "spry", "sturdy", "tranquil", "upbeat", "vivid", "wise", "witty", "zealous",
+]
+
+ADJECTIVES_B = [
+    "amber", "azure", "bronze", "coral", "crimson", "cyan", "emerald", "golden",
+    "green", "indigo", "ivory", "jade", "lavender", "lilac", "magenta", "maroon",
+    "mauve", "navy", "olive", "orange", "peach", "pink", "plum", "purple",
+    "red", "rust", "ruby", "sage", "salmon", "scarlet", "sienna", "silver",
+    "slate", "tan", "teal", "turquoise", "violet", "yellow", "blue", "copper",
+]
+
+NOUNS = [
+    "antelope", "badger", "beetle", "bison", "cricket", "dolphin", "eagle", "elk",
+    "falcon", "ferret", "flamingo", "fox", "gazelle", "gecko", "hare", "heron",
+    "ibex", "iguana", "lynx", "marten", "mongoose", "moose", "narwhal", "orca",
+    "otter", "owl", "panther", "pelican", "penguin", "rabbit", "raven", "salamander",
+    "seal", "sparrow", "tiger", "toucan", "walrus", "weasel", "wolf", "wombat",
+]
+
+
+def petname(node_id: str) -> str:
+    """The stable "adjective_color_animal_0000" label for a node id:
+    same input, same output, on every tool and every machine."""
+    digest = hashlib.sha256(node_id.lower().encode("utf-8")).digest()
+    a = ADJECTIVES_A[int.from_bytes(digest[0:2], "big") % len(ADJECTIVES_A)]
+    b = ADJECTIVES_B[int.from_bytes(digest[2:4], "big") % len(ADJECTIVES_B)]
+    n = NOUNS[int.from_bytes(digest[4:6], "big") % len(NOUNS)]
+    suffix = int.from_bytes(digest[6:8], "big") % 10_000
+    return f"{a}_{b}_{n}_{suffix:04d}"

tests/test_petname.py

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+from macula_py.petname import petname
+
+
+def test_petname_deterministic_and_shaped():
+    nid = "7374b0cfab4eea68e271c3815a0f78e21e913397f67345f337ddba7a3a88ab3a"
+    first = petname(nid)
+    assert petname(nid) == first
+    parts = first.split("_")
+    assert len(parts) == 4
+    assert len(parts[3]) == 4
+    assert parts[3].isdigit()
+
+
+def test_petname_matches_reference():
+    # Shared fixtures across the SDKs: one label everywhere. The second
+    # is proven against the live roster (gentle_maroon_flamingo before
+    # the suffix shipped).
+    assert (
+        petname("7374b0cfab4eea68e271c3815a0f78e21e913397f67345f337ddba7a3a88ab3a")
+        == "calm_navy_narwhal_3381"
+    )
+    assert (
+        petname("d4b24382f4e033ad9e895070c914c8125c315f243c5a3713183352f65c322b03")
+        == "gentle_maroon_flamingo_3490"
+    )