Tianyi Cui
5717726835
Drop SubprocessSpawnSpec.dshEnv and splitEnvChannels(); childEnv() is now scrubbed-base + explicit entries with no namespace validation. The invariant dropped is the reserved-namespace check on explicit entries (DSH_* rejected from env, non-DSH_* rejected from dshEnv). Explicit-entry trust already covers it: an explicit credential-shaped entry has always merged after the scrub as a deliberate caller opt-in, and an explicit DSH_* entry is the same deliberate act — the staleness invariant lives entirely in scrubbedParentEnv dropping AMBIENT credential-shaped and DSH_* names, which stays. The validation's only observed effect was rejecting legitimate explicit entries: both recent CI breakages (DSH_GATE_CONCURRENCY exported into every job crashing lsp specs, DSH_PERMISSION_MODE in acp config.env crashing the child spawn) were this check firing on values a caller meant to pass, each fixed by routing around the bureaucracy the seam itself imposed. The bash seam keeps its own request/spec dshEnv field: that is bash-owned trusted-plugin vocabulary (the ctx.bashEnv collected overlay) whose merge-last position guarantees a caller env entry cannot displace a managed fact; bash-local now flattens ENV_OVERRIDES -> spec.env -> spec.dshEnv into the seam's one env map. subagent-acp and lsp-local pass their single config env map straight through. DshEnvironment/DshEnvironmentKey/DSH_ENV_PREFIX stay on the subprocess seam as the namespace vocabulary (bash re-exports them; scrubbedParentEnv filters on the prefix). Tests: the two channel-rejection specs and the splitEnvChannels partition spec are deleted; one spawn spec now proves an explicit DSH_* env entry reaches the child while an ambient one is scrubbed; the acp/lsp forwarding specs keep their MOCK_ECHO_ENV / LSP_FAKE_ECHO_ENV assertions with the split comments rewritten to merge-after-scrub. Docs (en+zh, re-recorded) and the owning Agent Notes updated; cordis api/services catalogs regenerated.
88 lines
9.9 KiB
Markdown
88 lines
9.9 KiB
Markdown
# Agent Note: Expose agent session identity and JSONL location to tools and hooks
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Status: implemented
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English | [中文](2026-07-10-agent-session-identity-and-log-location.zh.md)
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## Problem
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An agent can identify its workspace through `session.header.cwd`, but a model using bash cannot reliably identify the session that owns the call or the durable transcript that records it. Searching `./.sessions` guesses deployment config and JSONL layout; custom roots, alternate persistence backends, resume, forks, and concurrent parent/child agents make that guess unreliable. Hooks have the same need for transcript location, while future plugins may need to expose other harness-owned environment facts to shell commands.
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The boundary must preserve two properties: the owner of a fact decides how to resolve it, and every child receives a per-execution snapshot rather than process-global mutable state. In particular, a nested harness must not leak its ambient `DSH_*` values into a child whose current agent, persistence backend, or configuration differs.
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## Decision
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Extend the [`SessionPersistence`](../architecture/2026-06-14-session-persistence.md) seam with a synchronous, side-effect-free location query:
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```ts
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import type { SessionHeader } from '@deepseek-ai/dsh-session'
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interface SessionLocation {
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readonly kind: string
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readonly path: string
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}
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interface SessionPersistence {
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locate(meta: SessionHeader): SessionLocation | undefined
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}
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```
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`path` is an absolute local path to the backend's dedicated log for `meta`; `kind` identifies the representation. JSONL returns `{ kind: 'jsonl', path }` using its resolved root and path helpers. SQLite and any backend without an honest local per-session artifact return `undefined`. The query creates and flushes nothing, so it can report a lazy target path before that file exists.
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The model-facing bash package owns a `ctx.bashEnv` registry. A contributor declares its stable name, every `DSH_*` key it may return, a description for each key, and `resolve(execution: ToolExecution)`. Duplicate contributor names, duplicate key ownership, reserved keys, malformed declarations, undeclared runtime output, and non-string output fail loudly. Registration is a Cordis effect and is removed with the contributing plugin fiber. `list()` exposes declarations without running resolvers, keeping the environment surface enumerable for diagnostics and future prompt/UI consumers.
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The registry rebuilds a trusted overlay for every foreground and background bash `ToolExecution`:
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- `DSH_HOME` is always the absolute configured Harness home. The standalone [`@deepseek-ai/dsh-paths`](../../../../packages/util/paths/README.md) utility owns its precedence: explicit `dshHome`, then ambient `$DSH_HOME`, then `~/.dsh`.
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- `DSH_SHELL=1` is always present and identifies a model bash child managed by DeepSeek Harness.
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- `DSH_SESSION_ID` is present when the execution has an agent and equals `agent.session.header.id`.
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- The built-in persistence translator contributes `DSH_SESSION_JSONL` only when `ctx.sessionPersistence.locate(header)` returns `kind: 'jsonl'`.
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Session persistence remains the fact owner: JSONL does not depend on tool-bash or register shell variables itself, and hooks continue to consume `locate()` directly. Tool-bash is the translation layer from the persistence fact into a shell convention. Other plugins that need shell-visible facts depend on the registry and register their own keys; they do not modify `process.env`.
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The bash seam exports `DSH_ENV_PREFIX` as the single namespace source and derives `DshEnvironmentKey` from its `typeof`. Tool-bash derives built-in names and model guidance from that constant, while executors use it for ambient filtering. The seam carries the managed overlay separately as `BashExecRequest.dshEnv` / `BashExecSpec.dshEnv`: ordinary `env` remains the general in-process plugin surface used by hooks, while `dshEnv` is typed to managed keys. The local executor removes every inherited ambient managed key, applies its ordinary scrub/terminal environment/explicit `env`, and finally merges the trusted `dshEnv` snapshot, so an `env` entry can never displace a managed value. This guarantees that a missing value means absent now rather than inherited from an outer or previous harness. The model-facing tool still ignores model-supplied `env`/`stdin` arguments.
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The bash tool description teaches only the durable convention: current harness environment facts are available through managed `$DSH_*` variables and may be inspected when needed. It does not enumerate persistence-specific keys or add a permanent system-prompt section. Tool schemas are already logged in request headers and tool output is logged as `tool/result`, so no new session event is required.
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The [Claude Code and Codex hook bridges](2026-06-30-hook-bridges.md) resolve transcript location from the same persistence seam when constructing payloads. Codex uses `transcript_path: string | null`; Claude Code preserves its string field and falls back to `''`. Hook lookup neither materializes nor flushes a session.
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## Peer product findings
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Peer products separate stable identity from physical storage. Codex injects stable `CODEX_THREAD_ID` into spawned shells while recorder and hook surfaces own transcript paths. Claude Code supplies `session_id` and `transcript_path` as structured hook/status input. OpenCode carries identity in structured tool context; Kimi Code expands a session placeholder; Reasonix keeps the active session path on its controller. The portable rule is to inject identity at the invocation boundary, let storage resolve location, and never use a process-global current-session variable in a concurrent harness.
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## Lifecycle and persistence semantics
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A fresh session receives its id before the first turn, so its first bash call can read `DSH_SESSION_ID` and a JSONL target. The JSONL file may still be absent until the first successful turn-end checkpoint, and during an open turn it contains only the last flushed prefix. `DSH_SESSION_JSONL` is a location hint, not an authorization credential or freshness guarantee.
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Resume reuses the loaded header and therefore the same id and location. Fork and spawn create new session ids and locations. Parent and child calls resolve from their own `ToolExecution.agent`; each command receives an immutable snapshot even when calls overlap. A persistence service replacement affects later collections because the translator queries `ctx.get('sessionPersistence')` at execution time; the registry itself is effect-scoped and HMR-safe.
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`dshHome` is session-independent deployment context. Agent-core resolves one value through `@deepseek-ai/dsh-paths` and routes it to both tool-bash and local skill discovery; standalone consumers call the same resolver. If top-level `dshHome` and `skills.local.dshHome` are both supplied and resolve differently, composition fails instead of exposing contradictory homes. Persistence may change independently without freezing its facts into the session prefix.
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## Testing
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Unit coverage pins registry declaration validation, effect disposal, per-execution collection, the `dshHome` precedence, and the local executor's `DSH_*` scrub/rebuild order. Request-recording tests cover foreground/background snapshots, no-agent calls, absent/JSONL persistence, ignored model `env`, and parent/child isolation. JSONL/SQLite locator contract tests and both hook bridge suites pin available and unavailable transcript dialects.
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A keyless full-loop integration drives the real agent loop, JSONL persistence, tool-bash, and bash-local on the first turn. The child prints `DSH_HOME`, `DSH_SHELL`, session id, JSONL target, and an inherited stale sentinel; the test verifies current values, absence of the stale variable, pre-flush file absence, and the eventual persisted header. Snapshot coverage pins the generic bash description in the recorded request header. No with-key test is required because the contract is deterministic local execution rather than model choice.
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## Alternatives considered
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**Only an id plus `find`.** Search cannot know a custom root or backend layout and races under multiple sessions.
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**Only an absolute path.** A path can be unavailable, lazy, or representation-specific and is not stable session identity.
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**Global `process.env`.** Concurrent agents would overwrite one another and nested harnesses would inherit stale current-session values.
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**Put persistence instructions in the session prefix.** A session prefix is frozen while the active service can change across HMR or future backend switching; persistence-specific guidance would become stale.
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**A typed waterfall event.** Listeners cannot declare ownership without running, and later listeners can silently overwrite keys. A registry detects key conflicts at registration and remains enumerable.
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**Have each persistence backend register bash env directly.** That reverses the dependency from storage into one consumer and forces bash into deployments that do not use it. `locate()` is also still required by hooks.
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**A model-facing `session_info` tool.** It adds schema and another call while bash already supplies the query surface; the registry generalizes to future environment facts without one tool per fact.
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## Consequences
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Every model bash child receives current Harness home and shell identity, and agent calls additionally receive stable session identity. JSONL-backed calls get an optional target path; non-file persistence omits it honestly. The managed `DSH_*` facts inside these children come from the harness: ambient values are removed, current trusted values are re-added last, and an ordinary caller's `env` entry cannot displace them.
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The namespace is discoverable but not secret. Paths can reveal configured roots, lazy targets can be absent or stale, and a command can override variables inside its own shell syntax. Consumers treat them as correlation and environment facts, verify transcript metadata when attribution matters, and rely on sandbox/filesystem policy rather than variable secrecy for authorization.
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