Codex ஆர்க்கெஸ்ட்ரேஷனுக்கான ஓப்பன்-சோர்ஸ் விவரக்குறிப்பு: Symphony

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# Symphony Service Specification
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Status: Draft v1 (language-agnostic)
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Purpose: Define a service that orchestrates coding agents to get project work done.
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## 1. Problem Statement
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Symphony is a long-running automation service that continuously reads work from an issue tracker
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(Linear in this specification version), creates an isolated workspace for each issue, and runs a
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coding agent session for that issue inside the workspace.
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The service solves four operational problems:
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- It turns issue execution into a repeatable daemon workflow instead of manual scripts.
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- It isolates agent execution in per-issue workspaces so agent commands run only inside per-issue
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  workspace directories.
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- It keeps the workflow policy in-repo (`WORKFLOW.md`) so teams version the agent prompt and runtime
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  settings with their code.
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- It provides enough observability to operate and debug multiple concurrent agent runs.
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Implementations are expected to document their trust and safety posture explicitly. This
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specification does not require a single approval, sandbox, or operator-confirmation policy; some
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implementations may target trusted environments with a high-trust configuration, while others may
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require stricter approvals or sandboxing.
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Important boundary:
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- Symphony is a scheduler/runner and tracker reader.
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- Ticket writes (state transitions, comments, PR links) are typically performed by the coding agent
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  using tools available in the workflow/runtime environment.
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- A successful run may end at a workflow-defined handoff state (for example `Human Review`), not
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  necessarily `Done`.
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## 2. Goals and Non-Goals
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### 2.1 Goals
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- Poll the issue tracker on a fixed cadence and dispatch work with bounded concurrency.
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- Maintain a single authoritative orchestrator state for dispatch, retries, and reconciliation.
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- Create deterministic per-issue workspaces and preserve them across runs.
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- Stop active runs when issue state changes make them ineligible.
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- Recover from transient failures with exponential backoff.
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- Load runtime behavior from a repository-owned `WORKFLOW.md` contract.
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- Expose operator-visible observability (at minimum structured logs).
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- Support restart recovery without requiring a persistent database.
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### 2.2 Non-Goals
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- Rich web UI or multi-tenant control plane.
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- Prescribing a specific dashboard or terminal UI implementation.
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- General-purpose workflow engine or distributed job scheduler.
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- Built-in business logic for how to edit tickets, PRs, or comments. (That logic lives in the
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  workflow prompt and agent tooling.)
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- Mandating strong sandbox controls beyond what the coding agent and host OS provide.
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- Mandating a single default approval, sandbox, or operator-confirmation posture for all
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  implementations.
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## 3. System Overview
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### 3.1 Main Components
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1. `Workflow Loader`
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   - Reads `WORKFLOW.md`.
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   - Parses YAML front matter and prompt body.
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   - Returns `{config, prompt_template}`.
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2. `Config Layer`
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   - Exposes typed getters for workflow config values.
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   - Applies defaults and environment variable indirection.
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   - Performs validation used by the orchestrator before dispatch.
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3. `Issue Tracker Client`
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   - Fetches candidate issues in active states.
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   - Fetches current states for specific issue IDs (reconciliation).
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   - Fetches terminal-state issues during startup cleanup.
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   - Normalizes tracker payloads into a stable issue model.
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4. `Orchestrator`
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   - Owns the poll tick.
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   - Owns the in-memory runtime state.
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   - Decides which issues to dispatch, retry, stop, or release.
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   - Tracks session metrics and retry queue state.
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5. `Workspace Manager`
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   - Maps issue identifiers to workspace paths.
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   - Ensures per-issue workspace directories exist.
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   - Runs workspace lifecycle hooks.
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   - Cleans workspaces for terminal issues.
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6. `Agent Runner`
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   - Creates workspace.
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   - Builds prompt from issue + workflow template.
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   - Launches the coding agent app-server client.
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   - Streams agent updates back to the orchestrator.
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7. `Status Surface` (optional)
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   - Presents human-readable runtime status (for example terminal output, dashboard, or other
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     operator-facing view).
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8. `Logging`
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   - Emits structured runtime logs to one or more configured sinks.
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### 3.2 Abstraction Levels
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Symphony is easiest to port when kept in these layers:
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1. `Policy Layer` (repo-defined)
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   - `WORKFLOW.md` prompt body.
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   - Team-specific rules for ticket handling, validation, and handoff.
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2. `Configuration Layer` (typed getters)
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   - Parses front matter into typed runtime settings.
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   - Handles defaults, environment tokens, and path normalization.
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3. `Coordination Layer` (orchestrator)
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   - Polling loop, issue eligibility, concurrency, retries, reconciliation.
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4. `Execution Layer` (workspace + agent subprocess)
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   - Filesystem lifecycle, workspace preparation, coding-agent protocol.
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5. `Integration Layer` (Linear adapter)
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   - API calls and normalization for tracker data.
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6. `Observability Layer` (logs + optional status surface)
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   - Operator visibility into orchestrator and agent behavior.
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### 3.3 External Dependencies
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- Issue tracker API (Linear for `tracker.kind: linear` in this specification version).
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- Local filesystem for workspaces and logs.
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- Optional workspace population tooling (for example Git CLI, if used).
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- Coding-agent executable that supports JSON-RPC-like app-server mode over stdio.
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- Host environment authentication for the issue tracker and coding agent.
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## 4. Core Domain Model
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### 4.1 Entities
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#### 4.1.1 Issue
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Normalized issue record used by orchestration, prompt rendering, and observability output.
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Fields:
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- `id` (string)
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  - Stable tracker-internal ID.
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- `identifier` (string)
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  - Human-readable ticket key (example: `ABC-123`).
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- `title` (string)
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- `description` (string or null)
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- `priority` (integer or null)
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  - Lower numbers are higher priority in dispatch sorting.
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- `state` (string)
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  - Current tracker state name.
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- `branch_name` (string or null)
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  - Tracker-provided branch metadata if available.
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- `url` (string or null)
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- `labels` (list of strings)
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  - Normalized to lowercase.
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- `blocked_by` (list of blocker refs)
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  - Each blocker ref contains:
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    - `id` (string or null)
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    - `identifier` (string or null)
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    - `state` (string or null)
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- `created_at` (timestamp or null)
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- `updated_at` (timestamp or null)
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#### 4.1.2 Workflow Definition
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Parsed `WORKFLOW.md` payload:
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- `config` (map)
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  - YAML front matter root object.
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- `prompt_template` (string)
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  - Markdown body after front matter, trimmed.
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#### 4.1.3 Service Config (Typed View)
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Typed runtime values derived from `WorkflowDefinition.config` plus environment resolution.
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Examples:
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- poll interval
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- workspace root
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- active and terminal issue states
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- concurrency limits
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- coding-agent executable/args/timeouts
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- workspace hooks
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#### 4.1.4 Workspace
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Filesystem workspace assigned to one issue identifier.
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Fields (logical):
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- `path` (workspace path; current runtime typically uses absolute paths, but relative roots are
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  possible if configured without path separators)
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- `workspace_key` (sanitized issue identifier)
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- `created_now` (boolean, used to gate `after_create` hook)
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#### 4.1.5 Run Attempt
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One execution attempt for one issue.
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Fields (logical):
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- `issue_id`
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- `issue_identifier`
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- `attempt` (integer or null, `null` for first run, `>=1` for retries/continuation)
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- `workspace_path`
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- `started_at`
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- `status`
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- `error` (optional)
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#### 4.1.6 Live Session (Agent Session Metadata)
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State tracked while a coding-agent subprocess is running.
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Fields:
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- `session_id` (string, `<thread_id>-<turn_id>`)
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- `thread_id` (string)
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- `turn_id` (string)
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- `codex_app_server_pid` (string or null)
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- `last_codex_event` (string/enum or null)
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- `last_codex_timestamp` (timestamp or null)
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- `last_codex_message` (summarized payload)
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- `codex_input_tokens` (integer)
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- `codex_output_tokens` (integer)
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- `codex_total_tokens` (integer)
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- `last_reported_input_tokens` (integer)
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- `last_reported_output_tokens` (integer)
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- `last_reported_total_tokens` (integer)
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- `turn_count` (integer)
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  - Number of coding-agent turns started within the current worker lifetime.
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#### 4.1.7 Retry Entry
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Scheduled retry state for an issue.
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Fields:
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- `issue_id`
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- `identifier` (best-effort human ID for status surfaces/logs)
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- `attempt` (integer, 1-based for retry queue)
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- `due_at_ms` (monotonic clock timestamp)
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- `timer_handle` (runtime-specific timer reference)
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- `error` (string or null)
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#### 4.1.8 Orchestrator Runtime State
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Single authoritative in-memory state owned by the orchestrator.
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Fields:
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- `poll_interval_ms` (current effective poll interval)
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- `max_concurrent_agents` (current effective global concurrency limit)
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- `running` (map `issue_id -> running entry`)
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- `claimed` (set of issue IDs reserved/running/retrying)
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- `retry_attempts` (map `issue_id -> RetryEntry`)
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- `completed` (set of issue IDs; bookkeeping only, not dispatch gating)
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- `codex_totals` (aggregate tokens + runtime seconds)
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- `codex_rate_limits` (latest rate-limit snapshot from agent events)
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### 4.2 Stable Identifiers and Normalization Rules
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- `Issue ID`
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  - Use for tracker lookups and internal map keys.
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- `Issue Identifier`
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  - Use for human-readable logs and workspace naming.
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- `Workspace Key`
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  - Derive from `issue.identifier` by replacing any character not in `[A-Za-z0-9._-]` with `_`.
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  - Use the sanitized value for the workspace directory name.
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- `Normalized Issue State`
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  - Compare states after `lowercase`.
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- `Session ID`
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  - Compose from coding-agent `thread_id` and `turn_id` as `<thread_id>-<turn_id>`.
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## 5. Workflow Specification (Repository Contract)
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### 5.1 File Discovery and Path Resolution
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Workflow file path precedence:
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1. Explicit application/runtime setting (set by CLI startup path).
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2. Default: `WORKFLOW.md` in the current process working directory.
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Loader behavior:
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- If the file cannot be read, return `missing_workflow_file` error.
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- The workflow file is expected to be repository-owned and version-controlled.
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### 5.2 File Format
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`WORKFLOW.md` is a Markdown file with optional YAML front matter.
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Design note:
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- `WORKFLOW.md` should be self-contained enough to describe and run different workflows (prompt,
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  runtime settings, hooks, and tracker selection/config) without requiring out-of-band
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  service-specific configuration.
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Parsing rules:
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- If file starts with `---`, parse lines until the next `---` as YAML front matter.
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- Remaining lines become the prompt body.
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- If front matter is absent, treat the entire file as prompt body and use an empty config map.
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- YAML front matter must decode to a map/object; non-map YAML is an error.
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- Prompt body is trimmed before use.
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Returned workflow object:
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- `config`: front matter root object (not nested under a `config` key).
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- `prompt_template`: trimmed Markdown body.
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### 5.3 Front Matter Schema
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Top-level keys:
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- `tracker`
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- `polling`
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- `workspace`
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- `hooks`
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- `agent`
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- `codex`
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Unknown keys should be ignored for forward compatibility.
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Note:
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- The workflow front matter is extensible. Optional extensions may define additional top-level keys
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  (for example `server`) without changing the core schema above.
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- Extensions should document their field schema, defaults, validation rules, and whether changes
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  apply dynamically or require restart.
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- Common extension: `server.port` (integer) enables the optional HTTP server described in Section
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  13.7.
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#### 5.3.1 `tracker` (object)
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Fields:
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- `kind` (string)
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  - Required for dispatch.
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  - Current supported value: `linear`
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- `endpoint` (string)
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  - Default for `tracker.kind == "linear"`: `https://api.linear.app/graphql`
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- `api_key` (string)
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  - May be a literal token or `$VAR_NAME`.
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  - Canonical environment variable for `tracker.kind == "linear"`: `LINEAR_API_KEY`.
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  - If `$VAR_NAME` resolves to an empty string, treat the key as missing.
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- `project_slug` (string)
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  - Required for dispatch when `tracker.kind == "linear"`.
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- `active_states` (list of strings)
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  - Default: `Todo`, `In Progress`
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- `terminal_states` (list of strings)
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  - Default: `Closed`, `Cancelled`, `Canceled`, `Duplicate`, `Done`
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#### 5.3.2 `polling` (object)
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Fields:
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- `interval_ms` (integer or string integer)
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  - Default: `30000`
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  - Changes should be re-applied at runtime and affect future tick scheduling without restart.
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#### 5.3.3 `workspace` (object)
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Fields:
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- `root` (path string or `$VAR`)
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  - Default: `<system-temp>/symphony_workspaces`
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  - `~` and strings containing path separators are expanded.
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  - Bare strings without path separators are preserved as-is (relative roots are allowed but
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    discouraged).
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#### 5.3.4 `hooks` (object)
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Fields:
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- `after_create` (multiline shell script string, optional)
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  - Runs only when a workspace directory is newly created.
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  - Failure aborts workspace creation.
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- `before_run` (multiline shell script string, optional)
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  - Runs before each agent attempt after workspace preparation and before launching the coding
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    agent.
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  - Failure aborts the current attempt.
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- `after_run` (multiline shell script string, optional)
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  - Runs after each agent attempt (success, failure, timeout, or cancellation) once the workspace
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    exists.
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  - Failure is logged but ignored.
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- `before_remove` (multiline shell script string, optional)
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  - Runs before workspace deletion if the directory exists.
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  - Failure is logged but ignored; cleanup still proceeds.
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- `timeout_ms` (integer, optional)
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  - Default: `60000`
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  - Applies to all workspace hooks.
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  - Non-positive values should be treated as invalid and fall back to the default.
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  - Changes should be re-applied at runtime for future hook executions.
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#### 5.3.5 `agent` (object)
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Fields:
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- `max_concurrent_agents` (integer or string integer)
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  - Default: `10`
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  - Changes should be re-applied at runtime and affect subsequent dispatch decisions.
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- `max_retry_backoff_ms` (integer or string integer)
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  - Default: `300000` (5 minutes)
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  - Changes should be re-applied at runtime and affect future retry scheduling.
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- `max_concurrent_agents_by_state` (map `state_name -> positive integer`)
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  - Default: empty map.
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  - State keys are normalized (`lowercase`) for lookup.
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  - Invalid entries (non-positive or non-numeric) are ignored.
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#### 5.3.6 `codex` (object)
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Fields:
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For Codex-owned config values such as `approval_policy`, `thread_sandbox`, and
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`turn_sandbox_policy`, supported values are defined by the targeted Codex app-server version.
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Implementors should treat them as pass-through Codex config values rather than relying on a
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hand-maintained enum in this spec. To inspect the installed Codex schema, run
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`codex app-server generate-json-schema --out <dir>` and inspect the relevant definitions referenced
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by `v2/ThreadStartParams.json` and `v2/TurnStartParams.json`. Implementations may validate these
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fields locally if they want stricter startup checks.
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- `command` (string shell command)
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  - Default: `codex app-server`
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  - The runtime launches this command via `bash -lc` in the workspace directory.
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  - The launched process must speak a compatible app-server protocol over stdio.
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- `approval_policy` (Codex `AskForApproval` value)
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  - Default: implementation-defined.
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- `thread_sandbox` (Codex `SandboxMode` value)
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  - Default: implementation-defined.
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- `turn_sandbox_policy` (Codex `SandboxPolicy` value)
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  - Default: implementation-defined.
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- `turn_timeout_ms` (integer)
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  - Default: `3600000` (1 hour)
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- `read_timeout_ms` (integer)
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  - Default: `5000`
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- `stall_timeout_ms` (integer)
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  - Default: `300000` (5 minutes)
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  - If `<= 0`, stall detection is disabled.
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### 5.4 Prompt Template Contract
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The Markdown body of `WORKFLOW.md` is the per-issue prompt template.
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Rendering requirements:
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- Use a strict template engine (Liquid-compatible semantics are sufficient).
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- Unknown variables must fail rendering.
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- Unknown filters must fail rendering.
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Template input variables:
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- `issue` (object)
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  - Includes all normalized issue fields, including labels and blockers.
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- `attempt` (integer or null)
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  - `null`/absent on first attempt.
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  - Integer on retry or continuation run.
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Fallback prompt behavior:
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- If the workflow prompt body is empty, the runtime may use a minimal default prompt
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  (`You are working on an issue from Linear.`).
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- Workflow file read/parse failures are configuration/validation errors and should not silently fall
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  back to a prompt.
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### 5.5 Workflow Validation and Error Surface
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Error classes:
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- `missing_workflow_file`
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- `workflow_parse_error`
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- `workflow_front_matter_not_a_map`
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- `template_parse_error` (during prompt rendering)
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- `template_render_error` (unknown variable/filter, invalid interpolation)
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Dispatch gating behavior:
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- Workflow file read/YAML errors block new dispatches until fixed.
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- Template errors fail only the affected run attempt.
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## 6. Configuration Specification
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### 6.1 Source Precedence and Resolution Semantics
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Configuration precedence:
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1. Workflow file path selection (runtime setting -> cwd default).
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2. YAML front matter values.
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3. Environment indirection via `$VAR_NAME` inside selected YAML values.
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4. Built-in defaults.
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Value coercion semantics:
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- Path/command fields support:
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  - `~` home expansion
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  - `$VAR` expansion for env-backed path values
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  - Apply expansion only to values intended to be local filesystem paths; do not rewrite URIs or
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    arbitrary shell command strings.
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### 6.2 Dynamic Reload Semantics
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Dynamic reload is required:
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- The software should watch `WORKFLOW.md` for changes.
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- On change, it should re-read and re-apply workflow config and prompt template without restart.
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- The software should attempt to adjust live behavior to the new config (for example polling
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  cadence, concurrency limits, active/terminal states, codex settings, workspace paths/hooks, and
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  prompt content for future runs).
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- Reloaded config applies to future dispatch, retry scheduling, reconciliation decisions, hook
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  execution, and agent launches.
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- Implementations are not required to restart in-flight agent sessions automatically when config
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  changes.
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- Extensions that manage their own listeners/resources (for example an HTTP server port change) may
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  require restart unless the implementation explicitly supports live rebind.
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- Implementations should also re-validate/reload defensively during runtime operations (for example
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  before dispatch) in case filesystem watch events are missed.
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- Invalid reloads should not crash the service; keep operating with the last known good effective
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  configuration and emit an operator-visible error.
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### 6.3 Dispatch Preflight Validation
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This validation is a scheduler preflight run before attempting to dispatch new work. It validates
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the workflow/config needed to poll and launch workers, not a full audit of all possible workflow
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behavior.
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Startup validation:
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- Validate configuration before starting the scheduling loop.
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- If startup validation fails, fail startup and emit an operator-visible error.
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Per-tick dispatch validation:
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- Re-validate before each dispatch cycle.
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- If validation fails, skip dispatch for that tick, keep reconciliation active, and emit an
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  operator-visible error.
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Validation checks:
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- Workflow file can be loaded and parsed.
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- `tracker.kind` is present and supported.
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- `tracker.api_key` is present after `$` resolution.
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- `tracker.project_slug` is present when required by the selected tracker kind.
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- `codex.command` is present and non-empty.
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### 6.4 Config Fields Summary (Cheat Sheet)
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This section is intentionally redundant so a coding agent can implement the config layer quickly.
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- `tracker.kind`: string, required, currently `linear`
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- `tracker.endpoint`: string, default `https://api.linear.app/graphql` when `tracker.kind=linear`
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- `tracker.api_key`: string or `$VAR`, canonical env `LINEAR_API_KEY` when `tracker.kind=linear`
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- `tracker.project_slug`: string, required when `tracker.kind=linear`
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- `tracker.active_states`: list of strings, default `["Todo", "In Progress"]`
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- `tracker.terminal_states`: list of strings, default `["Closed", "Cancelled", "Canceled", "Duplicate", "Done"]`
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- `polling.interval_ms`: integer, default `30000`
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- `workspace.root`: path, default `<system-temp>/symphony_workspaces`
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- `worker.ssh_hosts` (extension): list of SSH host strings, optional; when omitted, work runs
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  locally
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- `worker.max_concurrent_agents_per_host` (extension): positive integer, optional; shared per-host
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  cap applied across configured SSH hosts
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- `hooks.after_create`: shell script or null
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- `hooks.before_run`: shell script or null
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- `hooks.after_run`: shell script or null
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- `hooks.before_remove`: shell script or null
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- `hooks.timeout_ms`: integer, default `60000`
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- `agent.max_concurrent_agents`: integer, default `10`
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- `agent.max_turns`: integer, default `20`
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- `agent.max_retry_backoff_ms`: integer, default `300000` (5m)
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- `agent.max_concurrent_agents_by_state`: map of positive integers, default `{}`
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- `codex.command`: shell command string, default `codex app-server`
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- `codex.approval_policy`: Codex `AskForApproval` value, default implementation-defined
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- `codex.thread_sandbox`: Codex `SandboxMode` value, default implementation-defined
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- `codex.turn_sandbox_policy`: Codex `SandboxPolicy` value, default implementation-defined
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- `codex.turn_timeout_ms`: integer, default `3600000`
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- `codex.read_timeout_ms`: integer, default `5000`
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- `codex.stall_timeout_ms`: integer, default `300000`
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- `server.port` (extension): integer, optional; enables the optional HTTP server, `0` may be used
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  for ephemeral local bind, and CLI `--port` overrides it
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## 7. Orchestration State Machine
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The orchestrator is the only component that mutates scheduling state. All worker outcomes are
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reported back to it and converted into explicit state transitions.
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### 7.1 Issue Orchestration States
591

592
This is not the same as tracker states (`Todo`, `In Progress`, etc.). This is the service's internal
593
claim state.
594

595
1. `Unclaimed`
596
   - Issue is not running and has no retry scheduled.
597

598
2. `Claimed`
599
   - Orchestrator has reserved the issue to prevent duplicate dispatch.
600
   - In practice, claimed issues are either `Running` or `RetryQueued`.
601

602
3. `Running`
603
   - Worker task exists and the issue is tracked in `running` map.
604

605
4. `RetryQueued`
606
   - Worker is not running, but a retry timer exists in `retry_attempts`.
607

608
5. `Released`
609
   - Claim removed because issue is terminal, non-active, missing, or retry path completed without
610
     re-dispatch.
611
612
Important nuance:
613

614
- A successful worker exit does not mean the issue is done forever.
615
- The worker may continue through multiple back-to-back coding-agent turns before it exits.
616
- After each normal turn completion, the worker re-checks the tracker issue state.
617
- If the issue is still in an active state, the worker should start another turn on the same live
618
  coding-agent thread in the same workspace, up to `agent.max_turns`.
619
- The first turn should use the full rendered task prompt.
620
- Continuation turns should send only continuation guidance to the existing thread, not resend the
621
  original task prompt that is already present in thread history.
622
- Once the worker exits normally, the orchestrator still schedules a short continuation retry
623
  (about 1 second) so it can re-check whether the issue remains active and needs another worker
624
  session.
625

626
### 7.2 Run Attempt Lifecycle
627

628
A run attempt transitions through these phases:
629

630
1. `PreparingWorkspace`
631
2. `BuildingPrompt`
632
3. `LaunchingAgentProcess`
633
4. `InitializingSession`
634
5. `StreamingTurn`
635
6. `Finishing`
636
7. `Succeeded`
637
8. `Failed`
638
9. `TimedOut`
639
10. `Stalled`
640
11. `CanceledByReconciliation`
641

642
Distinct terminal reasons are important because retry logic and logs differ.
643

644
### 7.3 Transition Triggers
645

646
- `Poll Tick`
647
  - Reconcile active runs.
648
  - Validate config.
649
  - Fetch candidate issues.
650
  - Dispatch until slots are exhausted.
651

652
- `Worker Exit (normal)`
653
  - Remove running entry.
654
  - Update aggregate runtime totals.
655
  - Schedule continuation retry (attempt `1`) after the worker exhausts or finishes its in-process
656
    turn loop.
657
658
- `Worker Exit (abnormal)`
659
  - Remove running entry.
660
  - Update aggregate runtime totals.
661
  - Schedule exponential-backoff retry.
662

663
- `Codex Update Event`
664
  - Update live session fields, token counters, and rate limits.
665

666
- `Retry Timer Fired`
667
  - Re-fetch active candidates and attempt re-dispatch, or release claim if no longer eligible.
668

669
- `Reconciliation State Refresh`
670
  - Stop runs whose issue states are terminal or no longer active.
671

672
- `Stall Timeout`
673
  - Kill worker and schedule retry.
674

675
### 7.4 Idempotency and Recovery Rules
676

677
- The orchestrator serializes state mutations through one authority to avoid duplicate dispatch.
678
- `claimed` and `running` checks are required before launching any worker.
679
- Reconciliation runs before dispatch on every tick.
680
- Restart recovery is tracker-driven and filesystem-driven (no durable orchestrator DB required).
681
- Startup terminal cleanup removes stale workspaces for issues already in terminal states.
682

683
## 8. Polling, Scheduling, and Reconciliation
684

685
### 8.1 Poll Loop
686

687
At startup, the service validates config, performs startup cleanup, schedules an immediate tick, and
688
then repeats every `polling.interval_ms`.
689

690
The effective poll interval should be updated when workflow config changes are re-applied.
691

692
Tick sequence:
693

694
1. Reconcile running issues.
695
2. Run dispatch preflight validation.
696
3. Fetch candidate issues from tracker using active states.
697
4. Sort issues by dispatch priority.
698
5. Dispatch eligible issues while slots remain.
699
6. Notify observability/status consumers of state changes.
700

701
If per-tick validation fails, dispatch is skipped for that tick, but reconciliation still happens
702
first.
703

704
### 8.2 Candidate Selection Rules
705

706
An issue is dispatch-eligible only if all are true:
707

708
- It has `id`, `identifier`, `title`, and `state`.
709
- Its state is in `active_states` and not in `terminal_states`.
710
- It is not already in `running`.
711
- It is not already in `claimed`.
712
- Global concurrency slots are available.
713
- Per-state concurrency slots are available.
714
- Blocker rule for `Todo` state passes:
715
  - If the issue state is `Todo`, do not dispatch when any blocker is non-terminal.
716

717
Sorting order (stable intent):
718

719
1. `priority` ascending (1..4 are preferred; null/unknown sorts last)
720
2. `created_at` oldest first
721
3. `identifier` lexicographic tie-breaker
722

723
### 8.3 Concurrency Control
724

725
Global limit:
726

727
- `available_slots = max(max_concurrent_agents - running_count, 0)`
728

729
Per-state limit:
730

731
- `max_concurrent_agents_by_state[state]` if present (state key normalized)
732
- otherwise fallback to global limit
733

734
The runtime counts issues by their current tracked state in the `running` map.
735

736
Optional SSH host limit:
737

738
- When `worker.max_concurrent_agents_per_host` is set, each configured SSH host may run at most
739
  that many concurrent agents at once.
740
- Hosts at that cap are skipped for new dispatch until capacity frees up.
741

742
### 8.4 Retry and Backoff
743

744
Retry entry creation:
745

746
- Cancel any existing retry timer for the same issue.
747
- Store `attempt`, `identifier`, `error`, `due_at_ms`, and new timer handle.
748

749
Backoff formula:
750

751
- Normal continuation retries after a clean worker exit use a short fixed delay of `1000` ms.
752
- Failure-driven retries use `delay = min(10000 * 2^(attempt - 1), agent.max_retry_backoff_ms)`.
753
- Power is capped by the configured max retry backoff (default `300000` / 5m).
754

755
Retry handling behavior:
756

757
1. Fetch active candidate issues (not all issues).
758
2. Find the specific issue by `issue_id`.
759
3. If not found, release claim.
760
4. If found and still candidate-eligible:
761
   - Dispatch if slots are available.
762
   - Otherwise requeue with error `no available orchestrator slots`.
763
5. If found but no longer active, release claim.
764

765
Note:
766

767
- Terminal-state workspace cleanup is handled by startup cleanup and active-run reconciliation
768
  (including terminal transitions for currently running issues).
769
- Retry handling mainly operates on active candidates and releases claims when the issue is absent,
770
  rather than performing terminal cleanup itself.
771

772
### 8.5 Active Run Reconciliation
773

774
Reconciliation runs every tick and has two parts.
775

776
Part A: Stall detection
777

778
- For each running issue, compute `elapsed_ms` since:
779
  - `last_codex_timestamp` if any event has been seen, else
780
  - `started_at`
781
- If `elapsed_ms > codex.stall_timeout_ms`, terminate the worker and queue a retry.
782
- If `stall_timeout_ms <= 0`, skip stall detection entirely.
783

784
Part B: Tracker state refresh
785

786
- Fetch current issue states for all running issue IDs.
787
- For each running issue:
788
  - If tracker state is terminal: terminate worker and clean workspace.
789
  - If tracker state is still active: update the in-memory issue snapshot.
790
  - If tracker state is neither active nor terminal: terminate worker without workspace cleanup.
791
- If state refresh fails, keep workers running and try again on the next tick.
792

793
### 8.6 Startup Terminal Workspace Cleanup
794

795
When the service starts:
796

797
1. Query tracker for issues in terminal states.
798
2. For each returned issue identifier, remove the corresponding workspace directory.
799
3. If the terminal-issues fetch fails, log a warning and continue startup.
800

801
This prevents stale terminal workspaces from accumulating after restarts.
802

803
## 9. Workspace Management and Safety
804

805
### 9.1 Workspace Layout
806

807
Workspace root:
808

809
- `workspace.root` (normalized path; the current config layer expands path-like values and preserves
810
  bare relative names)
811

812
Per-issue workspace path:
813

814
- `<workspace.root>/<sanitized_issue_identifier>`
815

816
Workspace persistence:
817

818
- Workspaces are reused across runs for the same issue.
819
- Successful runs do not auto-delete workspaces.
820

821
### 9.2 Workspace Creation and Reuse
822

823
Input: `issue.identifier`
824

825
Algorithm summary:
826

827
1. Sanitize identifier to `workspace_key`.
828
2. Compute workspace path under workspace root.
829
3. Ensure the workspace path exists as a directory.
830
4. Mark `created_now=true` only if the directory was created during this call; otherwise
831
   `created_now=false`.
832
5. If `created_now=true`, run `after_create` hook if configured.
833

834
Notes:
835

836
- This section does not assume any specific repository/VCS workflow.
837
- Workspace preparation beyond directory creation (for example dependency bootstrap, checkout/sync,
838
  code generation) is implementation-defined and is typically handled via hooks.
839

840
### 9.3 Optional Workspace Population (Implementation-Defined)
841

842
The spec does not require any built-in VCS or repository bootstrap behavior.
843

844
Implementations may populate or synchronize the workspace using implementation-defined logic and/or
845
hooks (for example `after_create` and/or `before_run`).
846

847
Failure handling:
848

849
- Workspace population/synchronization failures return an error for the current attempt.
850
- If failure happens while creating a brand-new workspace, implementations may remove the partially
851
  prepared directory.
852
- Reused workspaces should not be destructively reset on population failure unless that policy is
853
  explicitly chosen and documented.
854

855
### 9.4 Workspace Hooks
856

857
Supported hooks:
858

859
- `hooks.after_create`
860
- `hooks.before_run`
861
- `hooks.after_run`
862
- `hooks.before_remove`
863

864
Execution contract:
865

866
- Execute in a local shell context appropriate to the host OS, with the workspace directory as
867
  `cwd`.
868
- On POSIX systems, `sh -lc <script>` (or a stricter equivalent such as `bash -lc <script>`) is a
869
  conforming default.
870
- Hook timeout uses `hooks.timeout_ms`; default: `60000 ms`.
871
- Log hook start, failures, and timeouts.
872

873
Failure semantics:
874

875
- `after_create` failure or timeout is fatal to workspace creation.
876
- `before_run` failure or timeout is fatal to the current run attempt.
877
- `after_run` failure or timeout is logged and ignored.
878
- `before_remove` failure or timeout is logged and ignored.
879

880
### 9.5 Safety Invariants
881

882
This is the most important portability constraint.
883

884
Invariant 1: Run the coding agent only in the per-issue workspace path.
885

886
- Before launching the coding-agent subprocess, validate:
887
  - `cwd == workspace_path`
888

889
Invariant 2: Workspace path must stay inside workspace root.
890

891
- Normalize both paths to absolute.
892
- Require `workspace_path` to have `workspace_root` as a prefix directory.
893
- Reject any path outside the workspace root.
894

895
Invariant 3: Workspace key is sanitized.
896

897
- Only `[A-Za-z0-9._-]` allowed in workspace directory names.
898
- Replace all other characters with `_`.
899

900
## 10. Agent Runner Protocol (Coding Agent Integration)
901

902
This section defines the language-neutral contract for integrating a coding agent app-server.
903

904
Compatibility profile:
905

906
- The normative contract is message ordering, required behaviors, and the logical fields that must
907
  be extracted (for example session IDs, completion state, approval handling, and usage/rate-limit
908
  telemetry).
909
- Exact JSON field names may vary slightly across compatible app-server versions.
910
- Implementations should tolerate equivalent payload shapes when they carry the same logical
911
  meaning, especially for nested IDs, approval requests, user-input-required signals, and
912
  token/rate-limit metadata.
913

914
### 10.1 Launch Contract
915

916
Subprocess launch parameters:
917

918
- Command: `codex.command`
919
- Invocation: `bash -lc <codex.command>`
920
- Working directory: workspace path
921
- Stdout/stderr: separate streams
922
- Framing: line-delimited protocol messages on stdout (JSON-RPC-like JSON per line)
923

924
Notes:
925

926
- The default command is `codex app-server`.
927
- Approval policy, cwd, and prompt are expressed in the protocol messages in Section 10.2.
928

929
Recommended additional process settings:
930

931
- Max line size: 10 MB (for safe buffering)
932

933
### 10.2 Session Startup Handshake
934

935
Reference: https://developers.openai.com/codex/app-server/
936

937
The client must send these protocol messages in order:
938

939
Illustrative startup transcript (equivalent payload shapes are acceptable if they preserve the same
940
semantics):
941

942
```json
943
{"id":1,"method":"initialize","params":{"clientInfo":{"name":"symphony","version":"1.0"},"capabilities":{}}}
944
{"method":"initialized","params":{}}
945
{"id":2,"method":"thread/start","params":{"approvalPolicy":"<implementation-defined>","sandbox":"<implementation-defined>","cwd":"/abs/workspace"}}
946
{"id":3,"method":"turn/start","params":{"threadId":"<thread-id>","input":[{"type":"text","text":"<rendered prompt-or-continuation-guidance>"}],"cwd":"/abs/workspace","title":"ABC-123: Example","approvalPolicy":"<implementation-defined>","sandboxPolicy":{"type":"<implementation-defined>"}}}
947
```
948

949
1. `initialize` request
950
   - Params include:
951
     - `clientInfo` object (for example `{name, version}`)
952
     - `capabilities` object (may be empty)
953
   - If the targeted Codex app-server requires capability negotiation for dynamic tools, include the
954
     necessary capability flag(s) here.
955
   - Wait for response (`read_timeout_ms`)
956
2. `initialized` notification
957
3. `thread/start` request
958
   - Params include:
959
     - `approvalPolicy` = implementation-defined session approval policy value
960
     - `sandbox` = implementation-defined session sandbox value
961
     - `cwd` = absolute workspace path
962
     - If optional client-side tools are implemented, include their advertised tool specs using the
963
       protocol mechanism supported by the targeted Codex app-server version.
964
4. `turn/start` request
965
   - Params include:
966
     - `threadId`
967
     - `input` = single text item containing rendered prompt for the first turn, or continuation
968
       guidance for later turns on the same thread
969
     - `cwd`
970
     - `title` = `<issue.identifier>: <issue.title>`
971
     - `approvalPolicy` = implementation-defined turn approval policy value
972
     - `sandboxPolicy` = implementation-defined object-form sandbox policy payload when required by
973
       the targeted app-server version
974
975
Session identifiers:
976

977
- Read `thread_id` from `thread/start` result `result.thread.id`
978
- Read `turn_id` from each `turn/start` result `result.turn.id`
979
- Emit `session_id = "<thread_id>-<turn_id>"`
980
- Reuse the same `thread_id` for all continuation turns inside one worker run
981

982
### 10.3 Streaming Turn Processing
983

984
The client reads line-delimited messages until the turn terminates.
985

986
Completion conditions:
987

988
- `turn/completed` -> success
989
- `turn/failed` -> failure
990
- `turn/cancelled` -> failure
991
- turn timeout (`turn_timeout_ms`) -> failure
992
- subprocess exit -> failure
993

994
Continuation processing:
995

996
- If the worker decides to continue after a successful turn, it should issue another `turn/start`
997
  on the same live `threadId`.
998
- The app-server subprocess should remain alive across those continuation turns and be stopped only
999
  when the worker run is ending.
1000

1001
Line handling requirements:
1002

1003
- Read protocol messages from stdout only.
1004
- Buffer partial stdout lines until newline arrives.
1005
- Attempt JSON parse on complete stdout lines.
1006
- Stderr is not part of the protocol stream:
1007
  - ignore it or log it as diagnostics
1008
  - do not attempt protocol JSON parsing on stderr
1009

1010
### 10.4 Emitted Runtime Events (Upstream to Orchestrator)
1011

1012
The app-server client emits structured events to the orchestrator callback. Each event should
1013
include:
1014

1015
- `event` (enum/string)
1016
- `timestamp` (UTC timestamp)
1017
- `codex_app_server_pid` (if available)
1018
- optional `usage` map (token counts)
1019
- payload fields as needed
1020

1021
Important emitted events may include:
1022

1023
- `session_started`
1024
- `startup_failed`
1025
- `turn_completed`
1026
- `turn_failed`
1027
- `turn_cancelled`
1028
- `turn_ended_with_error`
1029
- `turn_input_required`
1030
- `approval_auto_approved`
1031
- `unsupported_tool_call`
1032
- `notification`
1033
- `other_message`
1034
- `malformed`
1035

1036
### 10.5 Approval, Tool Calls, and User Input Policy
1037

1038
Approval, sandbox, and user-input behavior is implementation-defined.
1039

1040
Policy requirements:
1041

1042
- Each implementation should document its chosen approval, sandbox, and operator-confirmation
1043
  posture.
1044
- Approval requests and user-input-required events must not leave a run stalled indefinitely. An
1045
  implementation should either satisfy them, surface them to an operator, auto-resolve them, or
1046
  fail the run according to its documented policy.
1047

1048
Example high-trust behavior:
1049

1050
- Auto-approve command execution approvals for the session.
1051
- Auto-approve file-change approvals for the session.
1052
- Treat user-input-required turns as hard failure.
1053

1054
Unsupported dynamic tool calls:
1055

1056
- Supported dynamic tool calls that are explicitly implemented and advertised by the runtime should
1057
  be handled according to their extension contract.
1058
- If the agent requests a dynamic tool call (`item/tool/call`) that is not supported, return a tool
1059
  failure response and continue the session.
1060
- This prevents the session from stalling on unsupported tool execution paths.
1061

1062
Optional client-side tool extension:
1063

1064
- An implementation may expose a limited set of client-side tools to the app-server session.
1065
- Current optional standardized tool: `linear_graphql`.
1066
- If implemented, supported tools should be advertised to the app-server session during startup
1067
  using the protocol mechanism supported by the targeted Codex app-server version.
1068
- Unsupported tool names should still return a failure result and continue the session.
1069

1070
`linear_graphql` extension contract:
1071

1072
- Purpose: execute a raw GraphQL query or mutation against Linear using Symphony's configured
1073
  tracker auth for the current session.
1074
- Availability: only meaningful when `tracker.kind == "linear"` and valid Linear auth is configured.
1075
- Preferred input shape:
1076

1077
  ```json
1078
  {
1079
    "query": "single GraphQL query or mutation document",
1080
    "variables": {
1081
      "optional": "graphql variables object"
1082
    }
1083
  }
1084
  ```
1085

1086
- `query` must be a non-empty string.
1087
- `query` must contain exactly one GraphQL operation.
1088
- `variables` is optional and, when present, must be a JSON object.
1089
- Implementations may additionally accept a raw GraphQL query string as shorthand input.
1090
- Execute one GraphQL operation per tool call.
1091
- If the provided document contains multiple operations, reject the tool call as invalid input.
1092
- `operationName` selection is intentionally out of scope for this extension.
1093
- Reuse the configured Linear endpoint and auth from the active Symphony workflow/runtime config; do
1094
  not require the coding agent to read raw tokens from disk.
1095
- Tool result semantics:
1096
  - transport success + no top-level GraphQL `errors` -> `success=true`
1097
  - top-level GraphQL `errors` present -> `success=false`, but preserve the GraphQL response body
1098
    for debugging
1099
  - invalid input, missing auth, or transport failure -> `success=false` with an error payload
1100
- Return the GraphQL response or error payload as structured tool output that the model can inspect
1101
  in-session.
1102
1103
Illustrative responses (equivalent payload shapes are acceptable if they preserve the same outcome):
1104

1105
```json
1106
{"id":"<approval-id>","result":{"approved":true}}
1107
{"id":"<tool-call-id>","result":{"success":false,"error":"unsupported_tool_call"}}
1108
```
1109

1110
Hard failure on user input requirement:
1111

1112
- If the agent requests user input, fail the run attempt immediately.
1113
- The client detects this via:
1114
  - explicit method (`item/tool/requestUserInput`), or
1115
  - turn methods/flags indicating input is required.
1116

1117
### 10.6 Timeouts and Error Mapping
1118

1119
Timeouts:
1120

1121
- `codex.read_timeout_ms`: request/response timeout during startup and sync requests
1122
- `codex.turn_timeout_ms`: total turn stream timeout
1123
- `codex.stall_timeout_ms`: enforced by orchestrator based on event inactivity
1124

1125
Error mapping (recommended normalized categories):
1126

1127
- `codex_not_found`
1128
- `invalid_workspace_cwd`
1129
- `response_timeout`
1130
- `turn_timeout`
1131
- `port_exit`
1132
- `response_error`
1133
- `turn_failed`
1134
- `turn_cancelled`
1135
- `turn_input_required`
1136

1137
### 10.7 Agent Runner Contract
1138

1139
The `Agent Runner` wraps workspace + prompt + app-server client.
1140

1141
Behavior:
1142

1143
1. Create/reuse workspace for issue.
1144
2. Build prompt from workflow template.
1145
3. Start app-server session.
1146
4. Forward app-server events to orchestrator.
1147
5. On any error, fail the worker attempt (the orchestrator will retry).
1148

1149
Note:
1150

1151
- Workspaces are intentionally preserved after successful runs.
1152

1153
## 11. Issue Tracker Integration Contract (Linear-Compatible)
1154

1155
### 11.1 Required Operations
1156

1157
An implementation must support these tracker adapter operations:
1158

1159
1. `fetch_candidate_issues()`
1160
   - Return issues in configured active states for a configured project.
1161

1162
2. `fetch_issues_by_states(state_names)`
1163
   - Used for startup terminal cleanup.
1164

1165
3. `fetch_issue_states_by_ids(issue_ids)`
1166
   - Used for active-run reconciliation.
1167

1168
### 11.2 Query Semantics (Linear)
1169

1170
Linear-specific requirements for `tracker.kind == "linear"`:
1171

1172
- `tracker.kind == "linear"`
1173
- GraphQL endpoint (default `https://api.linear.app/graphql`)
1174
- Auth token sent in `Authorization` header
1175
- `tracker.project_slug` maps to Linear project `slugId`
1176
- Candidate issue query filters project using `project: { slugId: { eq: $projectSlug } }`
1177
- Issue-state refresh query uses GraphQL issue IDs with variable type `[ID!]`
1178
- Pagination required for candidate issues
1179
- Page size default: `50`
1180
- Network timeout: `30000 ms`
1181

1182
Important:
1183

1184
- Linear GraphQL schema details can drift. Keep query construction isolated and test the exact query
1185
  fields/types required by this specification.
1186

1187
A non-Linear implementation may change transport details, but the normalized outputs must match the
1188
domain model in Section 4.
1189

1190
### 11.3 Normalization Rules
1191

1192
Candidate issue normalization should produce fields listed in Section 4.1.1.
1193

1194
Additional normalization details:
1195

1196
- `labels` -> lowercase strings
1197
- `blocked_by` -> derived from inverse relations where relation type is `blocks`
1198
- `priority` -> integer only (non-integers become null)
1199
- `created_at` and `updated_at` -> parse ISO-8601 timestamps
1200

1201
### 11.4 Error Handling Contract
1202

1203
Recommended error categories:
1204

1205
- `unsupported_tracker_kind`
1206
- `missing_tracker_api_key`
1207
- `missing_tracker_project_slug`
1208
- `linear_api_request` (transport failures)
1209
- `linear_api_status` (non-200 HTTP)
1210
- `linear_graphql_errors`
1211
- `linear_unknown_payload`
1212
- `linear_missing_end_cursor` (pagination integrity error)
1213

1214
Orchestrator behavior on tracker errors:
1215

1216
- Candidate fetch failure: log and skip dispatch for this tick.
1217
- Running-state refresh failure: log and keep active workers running.
1218
- Startup terminal cleanup failure: log warning and continue startup.
1219

1220
### 11.5 Tracker Writes (Important Boundary)
1221

1222
Symphony does not require first-class tracker write APIs in the orchestrator.
1223

1224
- Ticket mutations (state transitions, comments, PR metadata) are typically handled by the coding
1225
  agent using tools defined by the workflow prompt.
1226
- The service remains a scheduler/runner and tracker reader.
1227
- Workflow-specific success often means "reached the next handoff state" (for example
1228
  `Human Review`) rather than tracker terminal state `Done`.
1229
- If the optional `linear_graphql` client-side tool extension is implemented, it is still part of
1230
  the agent toolchain rather than orchestrator business logic.
1231

1232
## 12. Prompt Construction and Context Assembly
1233

1234
### 12.1 Inputs
1235

1236
Inputs to prompt rendering:
1237

1238
- `workflow.prompt_template`
1239
- normalized `issue` object
1240
- optional `attempt` integer (retry/continuation metadata)
1241

1242
### 12.2 Rendering Rules
1243

1244
- Render with strict variable checking.
1245
- Render with strict filter checking.
1246
- Convert issue object keys to strings for template compatibility.
1247
- Preserve nested arrays/maps (labels, blockers) so templates can iterate.
1248

1249
### 12.3 Retry/Continuation Semantics
1250

1251
`attempt` should be passed to the template because the workflow prompt may provide different
1252
instructions for:
1253

1254
- first run (`attempt` null or absent)
1255
- continuation run after a successful prior session
1256
- retry after error/timeout/stall
1257

1258
### 12.4 Failure Semantics
1259

1260
If prompt rendering fails:
1261

1262
- Fail the run attempt immediately.
1263
- Let the orchestrator treat it like any other worker failure and decide retry behavior.
1264

1265
## 13. Logging, Status, and Observability
1266

1267
### 13.1 Logging Conventions
1268

1269
Required context fields for issue-related logs:
1270

1271
- `issue_id`
1272
- `issue_identifier`
1273

1274
Required context for coding-agent session lifecycle logs:
1275

1276
- `session_id`
1277

1278
Message formatting requirements:
1279

1280
- Use stable `key=value` phrasing.
1281
- Include action outcome (`completed`, `failed`, `retrying`, etc.).
1282
- Include concise failure reason when present.
1283
- Avoid logging large raw payloads unless necessary.
1284

1285
### 13.2 Logging Outputs and Sinks
1286

1287
The spec does not prescribe where logs must go (stderr, file, remote sink, etc.).
1288

1289
Requirements:
1290

1291
- Operators must be able to see startup/validation/dispatch failures without attaching a debugger.
1292
- Implementations may write to one or more sinks.
1293
- If a configured log sink fails, the service should continue running when possible and emit an
1294
  operator-visible warning through any remaining sink.
1295

1296
### 13.3 Runtime Snapshot / Monitoring Interface (Optional but Recommended)
1297

1298
If the implementation exposes a synchronous runtime snapshot (for dashboards or monitoring), it
1299
should return:
1300

1301
- `running` (list of running session rows)
1302
- each running row should include `turn_count`
1303
- `retrying` (list of retry queue rows)
1304
- `codex_totals`
1305
  - `input_tokens`
1306
  - `output_tokens`
1307
  - `total_tokens`
1308
  - `seconds_running` (aggregate runtime seconds as of snapshot time, including active sessions)
1309
- `rate_limits` (latest coding-agent rate limit payload, if available)
1310

1311
Recommended snapshot error modes:
1312

1313
- `timeout`
1314
- `unavailable`
1315

1316
### 13.4 Optional Human-Readable Status Surface
1317

1318
A human-readable status surface (terminal output, dashboard, etc.) is optional and
1319
implementation-defined.
1320

1321
If present, it should draw from orchestrator state/metrics only and must not be required for
1322
correctness.
1323

1324
### 13.5 Session Metrics and Token Accounting
1325

1326
Token accounting rules:
1327

1328
- Agent events may include token counts in multiple payload shapes.
1329
- Prefer absolute thread totals when available, such as:
1330
  - `thread/tokenUsage/updated` payloads
1331
  - `total_token_usage` within token-count wrapper events
1332
- Ignore delta-style payloads such as `last_token_usage` for dashboard/API totals.
1333
- Extract input/output/total token counts leniently from common field names within the selected
1334
  payload.
1335
- For absolute totals, track deltas relative to last reported totals to avoid double-counting.
1336
- Do not treat generic `usage` maps as cumulative totals unless the event type defines them that
1337
  way.
1338
- Accumulate aggregate totals in orchestrator state.
1339

1340
Runtime accounting:
1341

1342
- Runtime should be reported as a live aggregate at snapshot/render time.
1343
- Implementations may maintain a cumulative counter for ended sessions and add active-session
1344
  elapsed time derived from `running` entries (for example `started_at`) when producing a
1345
  snapshot/status view.
1346
- Add run duration seconds to the cumulative ended-session runtime when a session ends (normal exit
1347
  or cancellation/termination).
1348
- Continuous background ticking of runtime totals is not required.
1349

1350
Rate-limit tracking:
1351

1352
- Track the latest rate-limit payload seen in any agent update.
1353
- Any human-readable presentation of rate-limit data is implementation-defined.
1354

1355
### 13.6 Humanized Agent Event Summaries (Optional)
1356

1357
Humanized summaries of raw agent protocol events are optional.
1358

1359
If implemented:
1360

1361
- Treat them as observability-only output.
1362
- Do not make orchestrator logic depend on humanized strings.
1363