Use `md5` hashed shm keys for macOS compat

Shorten SHM buffer key names to fit Darwin's 31
char filename limit by hashing the `fqme`/content
portion with `md5` and truncating to 8 hex chars.

Deats,
- `.fsp._api`: replace `piker.{actor}[{uuid}].{sym}`
  format with `{uuid[:8]}_{hash}.fsp`
- `.tsp._history`: add `platform.system()` check to
  conditionally shorten `.hist`/`.rt` keys on Darwin
  while keeping the full key format on Linux

(this commit msg was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code

NOTE that this patch was orig by @dnks and broken out from a larger
commit which added unnecessary/out-of-scope changes we didn't end up
requiring.

piker/fsp/_api.py

@@ -200,9 +200,13 @@ def maybe_mk_fsp_shm(
     )
 
     # (attempt to) uniquely key the fsp shm buffers
+    # Use hash for macOS compatibility (31 char limit)
+    import hashlib
     actor_name, uuid = tractor.current_actor().uid
-    uuid_snip: str = uuid[:16]
-    key: str = f'piker.{actor_name}[{uuid_snip}].{sym}.{target.name}'
+    # Create short hash of sym and target name
+    content = f'{sym}.{target.name}'
+    content_hash = hashlib.md5(content.encode()).hexdigest()[:8]
+    key: str = f'{uuid[:8]}_{content_hash}.fsp'
 
     shm, opened = maybe_open_shm_array(
         key,

piker/tsp/_history.py

@@ -32,6 +32,7 @@ from __future__ import annotations
 from datetime import datetime
 from functools import partial
 from pathlib import Path
+import platform
 from pprint import pformat
 from types import ModuleType
 from typing import (
@@ -1380,13 +1381,20 @@ async def manage_history(
     service: str = name.rstrip(f'.{mod.name}')
     fqme: str = mkt.get_fqme(delim_char='')
 
+    key: str = f'piker.{service}[{uuid[:16]}].{fqme}'
+    # use a short hash of the `fqme` to deal with macOS
+    # file-name-len limit..
+    if platform.system() == 'Darwin':
+        import hashlib
+        fqme_hash: str = hashlib.md5(fqme.encode()).hexdigest()[:8]
+        key: str = f'{uuid[:8]}_{fqme_hash}'
+
     # (maybe) allocate shm array for this broker/symbol which will
     # be used for fast near-term history capture and processing.
     hist_shm, opened = maybe_open_shm_array(
         size=_default_hist_size,
         append_start_index=_hist_buffer_start,
-
-        key=f'piker.{service}[{uuid[:16]}].{fqme}.hist',
+        key=f'{key}.hist',
 
         # use any broker defined ohlc dtype:
         dtype=getattr(mod, '_ohlc_dtype', def_iohlcv_fields),
@@ -1405,7 +1413,7 @@ async def manage_history(
     rt_shm, opened = maybe_open_shm_array(
         size=_default_rt_size,
         append_start_index=_rt_buffer_start,
-        key=f'piker.{service}[{uuid[:16]}].{fqme}.rt',
+        key=f'{key}.rt',
 
         # use any broker defined ohlc dtype:
         dtype=getattr(mod, '_ohlc_dtype', def_iohlcv_fields),