docs: consolidate session work-unit vocabulary (#35218)

specs/v2/session.md

@@ -47,7 +47,7 @@ SessionExecution.resume(sessionID)
 
 `SessionExecution` and the read-side `SessionStore` are process-global. `SessionRunner`, catalog, model resolver, tool registry, permission state, and filesystem are cached per Location. No layer takes a Session ID. An omitted `Location.workspaceID` means implicit-local placement; explicit workspace identity remains reserved for future placement semantics.
 
-The local runner issues one explicit `llm.stream(request)` per provider turn, projects each complete local tool call durably before eagerly starting its structured child execution, awaits every started tool fiber after provider-stream closure, and reloads projected history once before continuation. Promoting any new user input resets the selected agent's configured provider-turn allowance; multiple steers promoted at one boundary reset it once. Tool settlement events carry the owning assistant message ID because provider-local call IDs may repeat across turns. Before assembling a provider request, the runner durably fails any local tool still projected as `running` from a previous process with `Tool execution interrupted`; abandoned side effects are never silently replayed.
+The local runner issues one explicit `llm.stream(request)` per step, projects each complete local tool call durably before eagerly starting its structured child execution, awaits every started tool fiber after provider-stream closure, and reloads projected history once before continuation. Promoting any new user input resets the selected agent's configured step allowance; multiple steers promoted at one boundary reset it once. Tool settlement events carry the owning assistant message ID because provider-local call IDs may repeat across steps. Before assembling a provider request, the runner durably fails any local tool still projected as `running` from a previous process with `Tool execution interrupted`; abandoned side effects are never silently replayed.
 
 Projected hosted tools preserve call-side and settlement-side provider metadata separately so settlement and interruption recovery cannot erase continuation identifiers. Provider-native reasoning and provider metadata replay only while the historical assistant model matches the selected continuation model; after a model switch, visible reasoning text remains ordinary assistant text and provider-native metadata is omitted.
 
@@ -55,7 +55,7 @@ Projected hosted tools preserve call-side and settlement-side provider metadata
 
 V2 Sessions persist the exact privileged System Context shown to the model. A Context Epoch stores one immutable provider-cache baseline and a model-hidden structured snapshot used to compare independently observed Context Sources. Environment facts, the host-local date, ambient global/upward-project `AGENTS.md` files, and selected-agent available-skill guidance are the initial sources. Location-wide sources come from the System Context Registry; selected-agent guidance composes with them immediately before Context Epoch admission.
 
-The first complete observation initializes the epoch before any pending prompt becomes model-visible. If initial context is temporarily unavailable, execution stops while the prompt remains pending and retryable. On later provider turns, the runner promotes eligible input first, then reconciles current sources at the safe boundary. Changed context becomes one durable chronological System message, and its event commit advances the epoch snapshot atomically.
+The first complete observation initializes the epoch before any pending prompt becomes model-visible. If initial context is temporarily unavailable, execution stops while the prompt remains pending and retryable. On later steps, the runner promotes eligible input first, then reconciles current sources at the safe boundary. Changed context becomes one durable chronological System message, and its event commit advances the epoch snapshot atomically.
 
 ```text
 Client            Runner                         System Context Registry       Context Epoch Store       Session History         LLM
@@ -79,7 +79,7 @@ Client            Runner                         System Context Registry       C
    │                 ├─ Baseline + chronological history ─────────────────────────────────────────────────────────────────────────▶
 ```
 
-Agent and model selection are provider-turn scoped. A switch admitted after the current safe provider-turn boundary applies to the next provider turn without restarting the current turn or replacing the baseline. Agent-specific skill guidance remains a Context Source, so changed guidance is admitted as a chronological System message. A completed compaction causes the next provider attempt to render a fresh baseline directly from current complete context. A Session move clears the epoch so the destination Location initializes a complete baseline on its next run.
+Agent and model selection are step-scoped. A switch admitted after the current safe step boundary applies to the next step without restarting the current step or replacing the baseline. Agent-specific skill guidance remains a Context Source, so changed guidance is admitted as a chronological System message. A completed compaction causes the next physical attempt to render a fresh baseline directly from current complete context. A Session move clears the epoch so the destination Location initializes a complete baseline on its next run.
 
 ```text
 Session                            Epoch
@@ -110,15 +110,15 @@ Current Context Epoch follow-ups:
 
 ## Automatic Compaction
 
-Before each provider turn, the runner estimates the complete model-visible request and compares it with the selected model's context window minus absolute reserved headroom. The reserve is the greater of the requested/model output allowance and configured `compaction.buffer`. When the request exceeds that budget and older complete turns are available, the runner compacts before executing the pending turn.
+Before each step, the runner estimates the complete model-visible request and compares it with the selected model's context window minus absolute reserved headroom. The reserve is the greater of the requested/model output allowance and configured `compaction.buffer`. When the request exceeds that budget and older complete steps are available, the runner compacts before executing the pending step.
 
 Compaction keeps the full transcript durable while replacing its active model representation with one hidden checkpoint containing a structured rolling summary and token-bounded serialized recent context. Provider-native assistant, reasoning, and tool messages never survive across the boundary, avoiding signature and encrypted-reasoning failures when the earlier prefix changes.
 
-`compaction.started.1` durably identifies the attempt. Compaction deltas are live-only progress. `compaction.ended.1` durably stores the final summary and serialized recent context; only this completed event projects a model-visible compaction message. On the next provider attempt, the runner observes that completed compaction and directly renders a fresh Context Epoch baseline. A failed or interrupted attempt therefore leaves the previous history boundary active.
+`compaction.started.1` durably identifies the attempt. Compaction deltas are live-only progress. `compaction.ended.1` durably stores the final summary and serialized recent context; only this completed event projects a model-visible compaction message. On the next physical attempt, the runner observes that completed compaction and directly renders a fresh Context Epoch baseline. A failed or interrupted attempt therefore leaves the previous history boundary active.
 
-Repeated compactions update the previous structured summary with newly compacted messages. The runner then reloads projected history and executes the original pending turn.
+Repeated compactions update the previous structured summary with newly compacted messages. The runner then reloads projected history and executes the original pending step.
 
-When a provider rejects a request as context overflow before durable assistant output or tool execution, the runner attempts one overflow-triggered compaction even when the local estimate did not predict pressure. A completed checkpoint rebuilds the same logical provider turn with one remaining physical attempt. A second overflow, unavailable compaction, or overflow after durable output becomes the ordinary terminal failure; recovery never loops or replays partial side effects. Deterministic old tool-result pruning remains a separate follow-up.
+When a provider rejects a request as context overflow before durable assistant output or tool execution, the runner attempts one overflow-triggered compaction even when the local estimate did not predict pressure. A completed checkpoint rebuilds the same logical step with one remaining physical attempt. A second overflow, unavailable compaction, or overflow after durable output becomes the ordinary terminal failure; recovery never loops or replays partial side effects. Deterministic old tool-result pruning remains a separate follow-up.
 
 ## V1 Runtime Context Parity
 
@@ -131,18 +131,18 @@ Status: `complete` is usable in the native V2 path, `partial` covers only part o
 | Durable Context Source     | Environment facts and host-local date                                    | partial  | Add selected provider/model identity without making model selection a stale Location-wide value.                                       |
 | Durable Context Source     | Global and upward project instructions                                   | partial  | Decide whether V2 also discovers legacy `CLAUDE.md` and deprecated `CONTEXT.md`.                                                       |
 | Durable Context Source     | Configured local/glob and remote URL instructions                        | missing  | Add independent sources with explicit precedence, unavailable, and removal semantics.                                                  |
-| Durable Context Source     | Nearby nested instructions discovered after successful reads             | missing  | Persist discoveries and admit them at the next safe provider-turn boundary.                                                            |
+| Durable Context Source     | Nearby nested instructions discovered after successful reads             | missing  | Persist discoveries and admit them at the next safe step boundary.                                                                     |
 | Durable Context Source     | Selected-agent available skill guidance and skill-body loading           | partial  | Guidance and body exposure are permission-filtered; remove globally denied skill definitions during request-time tool materialization. |
-| Per-turn request assembly  | Placement, selected model, chronological history, and canonical lowering | complete | None.                                                                                                                                  |
-| Per-turn request assembly  | Selected agent, agent prompt, and effective permissions                  | partial  | V2 uses selected-agent permissions for skill guidance and tool authorization; still apply the agent system prompt and request policy.  |
-| Per-turn request assembly  | Provider/model-specific base instructions                                | complete | Native V2 selects the provider-family baseline unless the effective agent overrides it.                                                |
-| Per-turn request assembly  | Policy-filtered built-in, MCP, plugin, and structured-output tools       | partial  | Materialize definitions for the effective agent and request.                                                                           |
-| Per-turn request assembly  | Per-prompt system text and tool overrides                                | missing  | Design admission and durable replay semantics before exposing them.                                                                    |
-| Per-turn request assembly  | Steering, plan/build-switch, and final-step reminders                    | missing  | Add only reminders whose behavior remains part of V2.                                                                                  |
-| Per-turn request assembly  | Plugin message, system, parameter, and header transforms                 | missing  | Design V2 plugin hooks and lifecycle semantics.                                                                                        |
-| Per-turn request assembly  | Model variants and request settings                                      | partial  | Apply effective agent options and future plugin-mutated request settings.                                                              |
-| Per-turn request assembly  | Structured-output policy                                                 | missing  | Add prompt format, generated tool, tool choice, and model-visible policy together.                                                     |
-| Per-turn request assembly  | Automatic/context-pressure compaction                                    | complete | V2 initiates automatic and overflow-triggered compaction, then rebuilds the baseline from the completed checkpoint.                    |
+| Step request assembly      | Placement, selected model, chronological history, and canonical lowering | complete | None.                                                                                                                                  |
+| Step request assembly      | Selected agent, agent prompt, and effective permissions                  | partial  | V2 uses selected-agent permissions for skill guidance and tool authorization; still apply the agent system prompt and request policy.  |
+| Step request assembly      | Provider/model-specific base instructions                                | complete | Native V2 selects the provider-family baseline unless the effective agent overrides it.                                                |
+| Step request assembly      | Policy-filtered built-in, MCP, plugin, and structured-output tools       | partial  | Materialize definitions for the effective agent and request.                                                                           |
+| Step request assembly      | Per-prompt system text and tool overrides                                | missing  | Design admission and durable replay semantics before exposing them.                                                                    |
+| Step request assembly      | Steering, plan/build-switch, and final-step reminders                    | missing  | Add only reminders whose behavior remains part of V2.                                                                                  |
+| Step request assembly      | Plugin message, system, parameter, and header transforms                 | missing  | Design V2 plugin hooks and lifecycle semantics.                                                                                        |
+| Step request assembly      | Model variants and request settings                                      | partial  | Apply effective agent options and future plugin-mutated request settings.                                                              |
+| Step request assembly      | Structured-output policy                                                 | missing  | Add prompt format, generated tool, tool choice, and model-visible policy together.                                                     |
+| Step request assembly      | Automatic/context-pressure compaction                                    | complete | V2 initiates automatic and overflow-triggered compaction, then rebuilds the baseline from the completed checkpoint.                    |
 | Prompt/reference expansion | Durable typed prompt attachments                                         | complete | None.                                                                                                                                  |
 | Prompt/reference expansion | Native template and `@` mention expansion                                | missing  | Parse and resolve native V2 prompt input before durable admission.                                                                     |
 | Prompt/reference expansion | File, directory, media, and MCP-resource materialization                 | partial  | Materialize and normalize sources instead of lowering unresolved attachment metadata.                                                  |
@@ -154,23 +154,23 @@ Provider timeout, retry, and watchdog policy is intentionally deferred. The runn
 
 Inbox delivery is explicit:
 
-- `steer` inputs promote at the next safe provider-turn boundary, including continuation inside the current drain.
+- `steer` inputs promote at the next safe step boundary, including continuation inside the current drain.
 - `queue` inputs remain in a FIFO while the current drain requires continuation. When the Session would otherwise become idle, the runner promotes exactly one queued input, then reevaluates continuation before promoting another.
 
 Execution has two entry points:
 
-- `run` is an explicit resume. It joins any active execution or starts a forced drain while idle. A forced drain bypasses the no-eligible-input guard, but preparation may still fail before a provider attempt.
+- `run` is an explicit resume. It joins any active execution or starts a forced drain while idle. A forced drain bypasses the no-eligible-input guard, but preparation may still fail before a physical attempt.
 - `wake` reports newly recorded durable inbox work. Repeated wakes coalesce. A wake calls the provider only when it can promote eligible input.
 
 Post-crash continuation recovery is intentionally deferred. A wake does not infer that ambiguous provider work is safe to retry after an input has already been promoted. Explicit `run` may deliberately continue from durable projected history. A future recovery slice should model provider-dispatch ambiguity, required continuation, queued-input promotion, retry policy, and visible recovery status together. It must not assume an enclosing durable execution identity that the Session model does not otherwise need.
 
-A process-global `SessionRunCoordinator` serializes execution for each local Session while allowing different Sessions to run concurrently. Resumes join active execution, overlapping wakes coalesce into one follow-up, and interruption stops current process-local execution without deleting durable inbox work. The runner enters the Session's current Location when execution starts and fences each new provider turn against that Location.
+A process-global `SessionRunCoordinator` serializes execution for each local Session while allowing different Sessions to run concurrently. Resumes join active execution, overlapping wakes coalesce into one follow-up, and interruption stops current process-local execution without deleting durable inbox work. The runner enters the Session's current Location when execution starts and fences each new step against that Location.
 
 The coordinator's active registry is also the source for `sessions.active()`. It represents only foreground Session drains owned by the current process; background subagents and tasks do not add parent Sessions to this registry. The snapshot is runtime state and is empty after a process restart.
 
 Inbox promotion coalesces pending steers in durable admission order. Once continuation would otherwise end, it promotes one queued input at a time in FIFO order. Add explicit inbox backlog and steering-batch limits before exposing broad multi-caller admission or untrusted queue growth.
 
-Eager local-tool execution is intentionally unbounded in the current local slice. This minimizes tool latency but does not increase SQLite settlement throughput: Session-event publication remains serialized per provider turn. Before broadening exposure, revisit per-turn call limits, output truncation, and operational backpressure using observed workloads. The normalized Session event schemas remain experimental and unshipped; databases created by earlier experimental builds are disposable rather than compatibility targets.
+Eager local-tool execution is intentionally unbounded in the current local slice. This minimizes tool latency but does not increase SQLite settlement throughput: Session-event publication remains serialized per step. Before broadening exposure, revisit per-step call limits, output truncation, and operational backpressure using observed workloads. The normalized Session event schemas remain experimental and unshipped; databases created by earlier experimental builds are disposable rather than compatibility targets.
 
 The normalized Session event family and projected Session-message model predate this branch. This slice refines their replay contract: projected Session messages retain their source aggregate sequence so canonical context ordering and `sessions.messages(...)` pagination follow durable event order even when caller-supplied IDs differ; event time is carried by the envelope `created` field rather than duplicated in payloads. Consumers can use `sessions.log({ sessionID, after? })` to replay durable Session events after an aggregate sequence cursor, then tail durable events without a race. Live-only text, reasoning, and tool-input fragments remain available through EventV2 subscriptions for connected renderers; they are intentionally absent from the replayable Session stream.
 
@@ -209,7 +209,7 @@ The first V2 `apply_patch` leaf supports add, update, and delete hunks. It parse
 
 ### Current Runner Follow-Ups
 
-- Keep eager structured local-tool settlement: durably record each complete call, start its child execution immediately, await all started settlements after provider-turn consumption, persist every result, and reload history once before continuation.
+- Keep eager structured local-tool settlement: durably record each complete call, start its child execution immediately, await all started settlements after step consumption, persist every result, and reload history once before continuation.
 - Buffer or coalesce streamed deltas before rewriting growing assistant projections.
 - Revisit additional covering indexes as larger-history query shapes become concrete.
 - Design any global multi-Session event stream separately; the finite history API deliberately reads one authorized Session aggregate and does not change global Event publication.

specs/v2/todo.md

@@ -21,17 +21,17 @@ through legacy `SessionPrompt.loop(...)`:
 - process-global `SessionExecution.resume(sessionID)` discovers Location from
   the Session read model
 - cached Location-scoped `SessionRunner` resolves one supported catalog model
-  and issues one explicit `llm.stream(request)` provider turn at a time
+  and issues one explicit `llm.stream(request)` step at a time
 - durable V2 projections record text, reasoning, provider failures, tool calls,
   tool results, and assistant output
 - a scoped `ToolRegistry` advertises definitions and the first permission-checked
   `read` built-in
-- local continuation reloads projected history, and promoting new user input resets the selected agent's configured provider-turn allowance
+- local continuation reloads projected history, and promoting new user input resets the selected agent's configured step allowance
 - concurrent resumes for one Session join one process-local run while different
   Sessions remain concurrent
 
 Prompt admission now uses a durable `session_input` inbox rather than immediate
-transcript projection. `steer` inputs promote at the next safe provider-turn
+transcript projection. `steer` inputs promote at the next safe step
 boundary while the current drain requires continuation. `queue` inputs remain in
 a FIFO until the Session would otherwise become idle and then promote one at a time.
 
@@ -39,12 +39,12 @@ Next reviewed slices:
 
 - preserve eager structured local-tool settlement: durably record each complete
   call, start its child execution immediately, await every settlement after the
-  provider turn closes, then reload projected history once
-- revisit per-turn tool-call limits, output truncation, and operational
+  step closes, then reload projected history once
+- revisit per-step tool-call limits, output truncation, and operational
   backpressure before broadening exposure; eager local execution is deliberately
   unbounded in the current local slice while SQLite publication stays serialized
 - remove the public in-memory `@opencode-ai/llm` tool loop after replacing its
-  remaining one-turn native-adapter use with a narrow typed dispatcher
+  remaining single-step native-adapter use with a narrow typed dispatcher
 - batch streamed deltas and add covering context indexes
 - expose replayable Session event cursors over HTTP and the generated SDK where remote consumers need them
 - integrate the new Job service with V2 tool execution: support background
@@ -56,14 +56,14 @@ Next reviewed slices:
 ### Deferred durable continuation recovery
 
 Do not infer that ambiguous provider work is safe to retry from an advisory wake.
-The first inbox-driven runner intentionally omits outer provider-attempt markers
+The first inbox-driven runner intentionally omits outer physical-attempt markers
 until they have a concrete consumer and a complete recovery policy.
 
 Design post-crash continuation recovery as one explicit slice. It should model:
 
 - promoted input and projected-history state
 - queued-input promotion and steering assignment
-- provider-attempt preparation versus provider-dispatch ambiguity
+- physical-attempt preparation versus provider-dispatch ambiguity
 - required post-tool continuation across process loss
 - explicit `retry` and `abandon` decisions for unknown outcomes
 - bounded automatic retry only where provider and tool idempotency make it safe

specs/v2/tools.md

@@ -148,7 +148,7 @@ Invalid input never invokes the tool. Invalid output never produces a successful
 
 `toModelOutput` is pure and total. When omitted, the encoded output remains structured output; an encoded string is also projected as text. Projection does not receive invocation identity because presentation depends only on validated input and output.
 
-Provider-turn materialization captures the effective registration identity for each advertised name without retaining its handler. Settlement rejects the call as stale if that registration was removed or replaced, including when closing an overlay reveals the previously effective registration. The current handler is captured only after this check; removing or replacing its registration afterward does not affect the running invocation.
+Step materialization captures the effective registration identity for each advertised name without retaining its handler. Settlement rejects the call as stale if that registration was removed or replaced, including when closing an overlay reveals the previously effective registration. The current handler is captured only after this check; removing or replacing its registration afterward does not affect the running invocation.
 
 ## Output Bounding
 
@@ -176,7 +176,7 @@ Leaf tools translate only errors they deliberately classify as recoverable. Broa
 - **Durable identity:** invocation-owned records use the exact Session, agent, assistant message, and call IDs supplied by the runner.
 - **Scoped registration:** closing a Scope removes exactly its registration and reveals any prior active overlay.
 - **Captured execution:** registration changes cannot alter an invocation after effective lookup.
-- **Stale rejection:** a call never executes a registration other than the one advertised for its provider turn.
+- **Stale rejection:** a call never executes a registration other than the one advertised for its step.
 - **Storage encapsulation:** domain output does not change according to model-output bounding or retention policy.
 
 ## Follow-Up