init_agent (2711 LOC) becomes a ~280-line ordered orchestrator over
_resolve_api_mode / _finalize_routing / _init_* / _build_client /
_load_tools / _parse_compression_config -> CompressionSettings /
_resolve_context_length / _build_context_engine / ... phase helpers.
_build_client is further split per wire mode (_init_anthropic_client,
_init_moa_client, _init_bedrock_client, _init_openai_client with
_explicit_client_kwargs / _routed_client_kwargs). Statement order and
every side effect on the agent are preserved (AST body-parity checked
against origin/main).
Dedupe/dead code: drop _relay_moa_reference_event/_moa_reference_output_allowed
(zero callers; only their own test) and their test file; alias
_normalize_route_base_url; _parse_config_int replaces three copies of the
strict int parser; _cfg_flag replaces four inline truthy-set checks;
_client_kwargs_from_routed + _fallback_entries replace duplicated
routed-client/fallback-entry blocks; _warn_invalid_config_int unifies the
three log+stderr invalid-int warnings (byte-identical text);
_bedrock_region_from_url; _memory_provider_init_kwargs; the
host->default_headers if/elif chain becomes the _HOST_DEFAULT_HEADERS
dispatch table; callback params assigned from _CALLBACK_PARAMS.
Comments/docstrings hand-compacted to their rationale (invariants,
ordering, failure modes kept; issue numbers and narrative dropped).
test_pre_compress_checkpoint_contract source-check repointed at the
CompressionSettings field names.
Verified: tests/run_agent (2066 passed) + all agent_init-referencing tests
(1134 passed), get_tool_definitions() byte-identical vs origin/main, import
smokes for cli/run_agent/gateway.run/hermes_cli.main/agent.conversation_loop/
tui_gateway.server.
Hardening on top of @Soju06's forwarding fix: v2 providers written against
the original docs example (def on_pre_compress(self, messages)) must not
TypeError when the host forwards require_checkpoint — inspect the signature
and fall back to the legacy call shape. Docs example updated to advertise
the keyword.
MemoryManager.on_pre_compress() detects checkpoint API v2 providers,
selects the normalized evidence list for them, and re-raises their
failures under require_checkpoint — but it never tells the provider
that a checkpoint is required: the call passes only the messages.
A v2 provider therefore runs in its default best-effort mode, swallows
durable-write failures, and returns normally; the host then treats the
checkpoint as succeeded and lossy compression proceeds. With
compression.checkpoint_required: true this silently defeats the
guarantee the option exists to provide.
Forward require_checkpoint only to providers advertising the requested
checkpoint API version. Legacy providers keep the strict one-argument
on_pre_compress(self, messages) contract, so bundled v1 providers
(honcho, mem0, supermemory, ...) are unaffected.
Regression tests cover required and best-effort signaling, legacy
signature compatibility, and required-mode failure propagation.
Independent review caught a compaction authority the gate missed:
post-turn micro-compaction (turn_finalizer -> _micro_compact) absorbs the
oldest exchanges into a rolling summary with no pre-compress checkpoint
hook in its path, and both compression.checkpoint_required and
compression.micro_compact could be enabled together — assistant evidence
could vanish into a summary the checkpoint filter later excludes, without
ever reaching the durable provider.
- agent_init: checkpoint_required forces micro-compaction off (warned),
mirroring the native-compaction suppression
- turn_finalizer: defense-in-depth guard at the call site (attribute is
plain mutable state a future path could flip on a live agent)
- behavioral regression test with a sabotage control (gate off proves the
harness reaches the call site; gate armed proves zero calls)
- docs + config example mention the suppression; stale v1 test header fixed
Per review: existing providers should not be retroactively re-versioned or
handed a changed payload. Version 1 is now the implicit historical
on_pre_compress() contract (best-effort, raw message list) that every
pre-existing provider is already on; the fail-closed checkpoint contract
becomes version 2. MemoryManager routes the raw transcript to v1 providers
unchanged and hands the host-normalized evidence list only to v2+ checkpoint
providers, so the plugin surface contract for shipped providers is
byte-identical with the gate off.
The fail-closed gate lived only in compress_context(), but two native
lossy owners compact without ever crossing it (review on #93996):
- codex app-server: in "native"/"off" auto-compaction mode (native is the
default) Hermes preflight is skipped and the codex agent compacts its
own thread inside run_turn() — the compress_context() rejection was
unreachable. init_agent now refuses checkpoint_required together with
api_mode=codex_app_server (BLOCKED_MISSING_PREREQUISITE, extracted as a
testable guard), and run_codex_app_server_turn() fails closed as
defense in depth before a turn can reach the codex-owned boundary.
- Responses server-side native compaction:
native_compaction_context_management() now returns None while the gate
is armed, so context_management never goes on the wire and the
checkpoint-aware Hermes compressor stays authoritative. The suppression
is logged once per process, not silently applied.
Regressions: checkpoint_required + app-server raises before run_turn()
(the session is never created); checkpoint_required keeps
context_management off the wire while the plain configuration still
produces it; the init guard refuses exactly the incompatible pair. Docs
and cli-config.yaml.example describe both bindings.
Refs #93986
Addresses the review on #93996:
- gateway: hygiene and manual /compress load the memory provider only when
compression.checkpoint_required is enabled (skip_memory=not required).
The historical fast path — no provider init, no best-effort hook — is
back for everyone who did not opt in, so default behavior is truly
unchanged.
- conversation_compression: assistant messages carrying both prose and
tool_calls keep their prose in the checkpoint evidence (the tool_calls
payload is stripped, the original message is not mutated); pure
tool-call wrappers without prose are still dropped.
- tests: legacy-database regression proving the _compressed_summary column
is added by the declarative _reconcile_columns() path on a plain reopen
(no version-gated migration needed — append_message works right after),
plus coverage for the prose-preserving filter.
- docs: providers must implement idempotent, content-keyed checkpoint
writes — a fail-closed block means the next attempt re-runs
on_pre_compress over largely the same transcript.
Refs #93986
Context compression is intentionally lossy. Deployments that archive
transcript evidence to an external durable store before compaction had no
way to guarantee the archive actually happened: MemoryManager.on_pre_compress
swallows provider failures by design, so a failed archive silently degraded
into data loss.
This adds an opt-in, provider-agnostic checkpoint contract:
- memory_provider: PRE_COMPRESS_CHECKPOINT_API_VERSION = 1; providers opt in
by advertising pre_compress_checkpoint_api_version. Version 0 keeps the
historical best-effort hook semantics.
- memory_manager: supports_pre_compress_checkpoint() capability probe;
on_pre_compress(require_checkpoint=True) propagates checkpoint-provider
failures and raises when no capable provider completed the checkpoint.
- conversation_compression: new compression.checkpoint_required config key
(default false, documented in cli-config.yaml.example). When enabled,
compaction fails closed with BLOCKED_MISSING_PREREQUISITE (the
uncompressed transcript is preserved) unless a checkpoint-capable provider
confirms the durable checkpoint. Providers receive normalized direct
user/assistant evidence: tool rows, system messages, tool-call wrappers,
and prior compaction summaries are filtered host-side into one stable
contract. codex_app_server compaction is rejected under the gate because
it exposes no truthful pre-compaction transcript boundary.
- hermes_state: persistent _compressed_summary column (declarative schema
migration via _reconcile_columns) so summary provenance survives process
restarts; only the resume model history carries the marker, keeping
get_messages_as_conversation on its existing contract.
- gateway: the lossy hygiene/auto-compact paths load the memory provider
(skip_memory=False) so a required checkpoint also guards those rewrites.
The gate arms only on an explicit boolean True (bare-MagicMock agents in
existing tests have truthy auto-attributes). Default behavior is unchanged:
checkpoint_required=false preserves best-effort semantics for all existing
providers. Contract tests, including a restart round-trip of the summary
marker, in tests/agent/test_pre_compress_checkpoint_contract.py.
Refs #93986
Teknium