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fix: robust context engine interface — config selection, plugin discovery, ABC completeness

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Follow-up fixes for the context engine plugin slot (PR #5700):

- Enhance ContextEngine ABC: add threshold_percent, protect_first_n,
  protect_last_n as class attributes; complete update_model() default
  with threshold recalculation; clarify on_session_end() lifecycle docs
- Add ContextCompressor.update_model() override for model/provider/
  base_url/api_key updates
- Replace all direct compressor internal access in run_agent.py with
  ABC interface: switch_model(), fallback restore, context probing
  all use update_model() now; _context_probed guarded with getattr/
  hasattr for plugin engine compatibility
- Create plugins/context_engine/ directory with discovery module
  (mirrors plugins/memory/ pattern) — discover_context_engines(),
  load_context_engine()
- Add context.engine config key to DEFAULT_CONFIG (default: compressor)
- Config-driven engine selection in run_agent.__init__: checks config,
  then plugins/context_engine/<name>/, then general plugin system,
  falls back to built-in ContextCompressor
- Wire on_session_end() in shutdown_memory_provider() at real session
  boundaries (CLI exit, /reset, gateway expiry)
This commit is contained in:
Teknium
2026-04-08 04:16:58 -07:00
committed by Teknium
parent 5d8dd622bc
commit 3fe6938176
5 changed files with 388 additions and 64 deletions
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175
run_agent.py
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@@ -1268,18 +1268,54 @@ class AIAgent:
pass
break
# Check if a plugin registered a custom context engine (e.g. LCM)
_plugin_engine = None
# Select context engine: config-driven (like memory providers).
# 1. Check config.yaml context.engine setting
# 2. Check plugins/context_engine/<name>/ directory (repo-shipped)
# 3. Check general plugin system (user-installed plugins)
# 4. Fall back to built-in ContextCompressor
_selected_engine = None
_engine_name = "compressor" # default
try:
from hermes_cli.plugins import get_plugin_context_engine
_plugin_engine = get_plugin_context_engine()
_ctx_cfg = _agent_cfg.get("context", {}) if isinstance(_agent_cfg, dict) else {}
_engine_name = _ctx_cfg.get("engine", "compressor") or "compressor"
except Exception:
pass
if _plugin_engine is not None:
self.context_compressor = _plugin_engine
if _engine_name != "compressor":
# Try loading from plugins/context_engine/<name>/
try:
from plugins.context_engine import load_context_engine
_selected_engine = load_context_engine(_engine_name)
except Exception as _ce_load_err:
logger.debug("Context engine load from plugins/context_engine/: %s", _ce_load_err)
# Try general plugin system as fallback
if _selected_engine is None:
try:
from hermes_cli.plugins import get_plugin_context_engine
_candidate = get_plugin_context_engine()
if _candidate and _candidate.name == _engine_name:
_selected_engine = _candidate
except Exception:
pass
if _selected_engine is None:
logger.warning(
"Context engine '%s' not found — falling back to built-in compressor",
_engine_name,
)
else:
# Even with default config, check if a plugin registered one
try:
from hermes_cli.plugins import get_plugin_context_engine
_selected_engine = get_plugin_context_engine()
except Exception:
pass
if _selected_engine is not None:
self.context_compressor = _selected_engine
if not self.quiet_mode:
logger.info("Using plugin context engine: %s", _plugin_engine.name)
logger.info("Using context engine: %s", _selected_engine.name)
else:
self.context_compressor = ContextCompressor(
model=self.model,
@@ -1385,11 +1421,13 @@ class AIAgent:
"api_key": getattr(self, "api_key", ""),
"client_kwargs": dict(self._client_kwargs),
"use_prompt_caching": self._use_prompt_caching,
# Compressor state that _try_activate_fallback() overwrites
"compressor_model": _cc.model,
"compressor_base_url": _cc.base_url,
# Context engine state that _try_activate_fallback() overwrites.
# Use getattr for model/base_url/api_key/provider since plugin
# engines may not have these (they're ContextCompressor-specific).
"compressor_model": getattr(_cc, "model", self.model),
"compressor_base_url": getattr(_cc, "base_url", self.base_url),
"compressor_api_key": getattr(_cc, "api_key", ""),
"compressor_provider": _cc.provider,
"compressor_provider": getattr(_cc, "provider", self.provider),
"compressor_context_length": _cc.context_length,
"compressor_threshold_tokens": _cc.threshold_tokens,
}
@@ -1518,13 +1556,12 @@ class AIAgent:
provider=self.provider,
config_context_length=getattr(self, "_config_context_length", None),
)
self.context_compressor.model = self.model
self.context_compressor.base_url = self.base_url
self.context_compressor.api_key = self.api_key
self.context_compressor.provider = self.provider
self.context_compressor.context_length = new_context_length
self.context_compressor.threshold_tokens = int(
new_context_length * self.context_compressor.threshold_percent
self.context_compressor.update_model(
model=self.model,
context_length=new_context_length,
base_url=self.base_url,
api_key=getattr(self, "api_key", ""),
provider=self.provider,
)
# ── Invalidate cached system prompt so it rebuilds next turn ──
@@ -1540,10 +1577,10 @@ class AIAgent:
"api_key": getattr(self, "api_key", ""),
"client_kwargs": dict(self._client_kwargs),
"use_prompt_caching": self._use_prompt_caching,
"compressor_model": _cc.model if _cc else self.model,
"compressor_base_url": _cc.base_url if _cc else self.base_url,
"compressor_model": getattr(_cc, "model", self.model) if _cc else self.model,
"compressor_base_url": getattr(_cc, "base_url", self.base_url) if _cc else self.base_url,
"compressor_api_key": getattr(_cc, "api_key", "") if _cc else "",
"compressor_provider": _cc.provider if _cc else self.provider,
"compressor_provider": getattr(_cc, "provider", self.provider) if _cc else self.provider,
"compressor_context_length": _cc.context_length if _cc else 0,
"compressor_threshold_tokens": _cc.threshold_tokens if _cc else 0,
}
@@ -2740,10 +2777,11 @@ class AIAgent:
}
def shutdown_memory_provider(self, messages: list = None) -> None:
"""Shut down the memory provider — call at actual session boundaries.
"""Shut down the memory provider and context engine — call at actual session boundaries.
This calls on_session_end() then shutdown_all() on the memory
manager. NOT called per-turn — only at CLI exit, /reset, gateway
manager, and on_session_end() on the context engine.
NOT called per-turn — only at CLI exit, /reset, gateway
session expiry, etc.
"""
if self._memory_manager:
@@ -2755,6 +2793,15 @@ class AIAgent:
self._memory_manager.shutdown_all()
except Exception:
pass
# Notify context engine of session end (flush DAG, close DBs, etc.)
if hasattr(self, "context_compressor") and self.context_compressor:
try:
self.context_compressor.on_session_end(
self.session_id or "",
messages or [],
)
except Exception:
pass
def close(self) -> None:
"""Release all resources held by this agent instance.
@@ -5272,13 +5319,12 @@ class AIAgent:
self.model, base_url=self.base_url,
api_key=self.api_key, provider=self.provider,
)
self.context_compressor.model = self.model
self.context_compressor.base_url = self.base_url
self.context_compressor.api_key = self.api_key
self.context_compressor.provider = self.provider
self.context_compressor.context_length = fb_context_length
self.context_compressor.threshold_tokens = int(
fb_context_length * self.context_compressor.threshold_percent
self.context_compressor.update_model(
model=self.model,
context_length=fb_context_length,
base_url=self.base_url,
api_key=getattr(self, "api_key", ""),
provider=self.provider,
)
self._emit_status(
@@ -5338,14 +5384,15 @@ class AIAgent:
shared=True,
)
# ── Restore context compressor state ──
# ── Restore context engine state ──
cc = self.context_compressor
cc.model = rt["compressor_model"]
cc.base_url = rt["compressor_base_url"]
cc.api_key = rt["compressor_api_key"]
cc.provider = rt["compressor_provider"]
cc.context_length = rt["compressor_context_length"]
cc.threshold_tokens = rt["compressor_threshold_tokens"]
cc.update_model(
model=rt["compressor_model"],
context_length=rt["compressor_context_length"],
base_url=rt["compressor_base_url"],
api_key=rt["compressor_api_key"],
provider=rt["compressor_provider"],
)
# ── Reset fallback chain for the new turn ──
self._fallback_activated = False
@@ -8247,7 +8294,7 @@ class AIAgent:
# Cache discovered context length after successful call.
# Only persist limits confirmed by the provider (parsed
# from the error message), not guessed probe tiers.
if self.context_compressor._context_probed:
if getattr(self.context_compressor, "_context_probed", False):
ctx = self.context_compressor.context_length
if getattr(self.context_compressor, "_context_probe_persistable", False):
save_context_length(self.model, self.base_url, ctx)
@@ -8586,16 +8633,22 @@ class AIAgent:
compressor = self.context_compressor
old_ctx = compressor.context_length
if old_ctx > _reduced_ctx:
compressor.context_length = _reduced_ctx
compressor.threshold_tokens = int(
_reduced_ctx * compressor.threshold_percent
compressor.update_model(
model=self.model,
context_length=_reduced_ctx,
base_url=self.base_url,
api_key=getattr(self, "api_key", ""),
provider=self.provider,
)
compressor._context_probed = True
# Don't persist — this is a subscription-tier
# limitation, not a model capability. If the user
# later enables extra usage the 1M limit should
# come back automatically.
compressor._context_probe_persistable = False
# Context probing flags — only set on built-in
# compressor (plugin engines manage their own).
if hasattr(compressor, "_context_probed"):
compressor._context_probed = True
# Don't persist — this is a subscription-tier
# limitation, not a model capability. If the
# user later enables extra usage the 1M limit
# should come back automatically.
compressor._context_probe_persistable = False
self._vprint(
f"{self.log_prefix}⚠️ Anthropic long-context tier "
f"requires extra usage — reducing context: "
@@ -8759,17 +8812,25 @@ class AIAgent:
new_ctx = get_next_probe_tier(old_ctx)
if new_ctx and new_ctx < old_ctx:
compressor.context_length = new_ctx
compressor.threshold_tokens = int(new_ctx * compressor.threshold_percent)
compressor._context_probed = True
# Only persist limits parsed from the provider's
# error message (a real number). Guessed fallback
# tiers from get_next_probe_tier() should stay
# in-memory only — persisting them pollutes the
# cache with wrong values.
compressor._context_probe_persistable = bool(
parsed_limit and parsed_limit == new_ctx
compressor.update_model(
model=self.model,
context_length=new_ctx,
base_url=self.base_url,
api_key=getattr(self, "api_key", ""),
provider=self.provider,
)
# Context probing flags — only set on built-in
# compressor (plugin engines manage their own).
if hasattr(compressor, "_context_probed"):
compressor._context_probed = True
# Only persist limits parsed from the provider's
# error message (a real number). Guessed fallback
# tiers from get_next_probe_tier() should stay
# in-memory only — persisting them pollutes the
# cache with wrong values.
compressor._context_probe_persistable = bool(
parsed_limit and parsed_limit == new_ctx
)
self._vprint(f"{self.log_prefix}⚠️ Context length exceeded — stepping down: {old_ctx:,} → {new_ctx:,} tokens", force=True)
else:
self._vprint(f"{self.log_prefix}⚠️ Context length exceeded at minimum tier — attempting compression...", force=True)