---
title: "Calculate Critical Path"
method: POST
path: "/api/v1/analysis/cpm"
tags: ["Analysis"]
---

# Calculate Critical Path

`POST /api/v1/analysis/cpm`

## Request

- Base URL: `https://api.bellatorsi.com` (the document declares no server; this is the origin it was published from)
- URL: `https://api.bellatorsi.com/api/v1/analysis/cpm`
- Auth: none declared

Calculate Critical Path Method for a schedule.

This endpoint performs two-pass CPM calculation (forward + backward pass)
to determine critical path, project duration, and task timing.

**Algorithm Steps:**
1. Dependency parsing & DAG construction
2. Forward pass (calculate early dates)
3. Backward pass (calculate late dates)
4. Float calculation (total float, free float)
5. Critical path identification

**Standards Compliance:**
- DCMA Check #12: Critical Path Test
- GAO BP-6: Maintain Valid Critical Path
- PMBOK 6.5.2.2: Critical Path Method
- AACE RP 27R-03: Schedule Flexibility

**Task Limits:**
- Minimum: 1 task
- Maximum: 10,000 tasks (synchronous processing only)
- For larger schedules, use async health score API

**Dependency Format:**
- Simple: ["T1", "T2"] (assumes FS with zero lag)
- Rich: ["T1FS+2 d", "T2SS-1 d"] (relationship type + lag)

**Response Time:**
- 1-100 tasks: <10ms
- 101-500 tasks: <25ms
- 501-1,000 tasks: <50ms
- 1,001-5,000 tasks: <200ms
- 5,001-10,000 tasks: <500ms

Args:
    request: CPM calculation request with tasks and options
    api_key: API key for authentication (injected)
    protection: Bot detection and rate limiting results

Returns:
    CPMResponse with critical path, task timing, and optional network details

Raises:
    HTTPException 400: Invalid request (malformed JSON, validation errors, cycles)
    HTTPException 401: Invalid API key
    HTTPException 429: Rate limit exceeded
    HTTPException 500: Internal server error

## Headers

- `x-api-key` string, nullable
- `authorization` string, nullable
- `x-bellator-internal-dispatch` string, nullable

## Request body

- CPMRequest: Request model for CPM calculation.
  - `tasks` Task[], required: List of tasks in the schedule
    - `id` string, required: Unique task identifier
    - `duration_days` number: Task duration in days
    - `predecessors` union[]: List of predecessor task IDs or dependency links. Supports: 'T1', 'T1FS+5 d', 'T2SS-2 d', or DependencyLink objects
      - union
        - string
        - object
        - DependencyLink: Rich dependency link with relationship type and lag/lead. Supports parsing from various scheduling tool formats including: - MS Project: "10FS+5 d", "/path/file.mpp/10FS+5 d" - Primavera P6: Similar format with XER encoding - Server-based: "<ServerFile>10FS+5 d" - Simple: "10" (defaults to FS with zero lag) Examples: >>> DependencyLink(task_id="10", relationship_type="FS", lag_days=5.0) >>> DependencyLink.from_string("10FS+5 d") >>> DependencyLink.from_string("15SS-2 d")
          - `task_id` string, required: Predecessor task ID
          - `relationship_type` 'FS' | 'SS' | 'FF' | 'SF': Task relationship types per PMBOK 6.3.2.2. Attributes: FINISH_START: Predecessor finish → successor start (most common, ~90%) START_START: Predecessor start → successor start (~5%) FINISH_FINISH: Predecessor finish → successor finish (~4%) START_FINISH: Predecessor start → successor finish (rare, ~1%)
          - `lag_days` number: Lag (positive) or lead (negative) in days
          - `is_external` boolean: True if link to external project file
          - `external_path` string, nullable: Path to external file if is_external=True
    - `name` string, nullable: Task name
    - `resource` string, nullable: Resource assigned to task
    - `resources` string[]: List of resources assigned (for multi-resource tasks)
    - `percent_complete` number: Percent complete (0-100)
    - `physical_percent_complete` number, nullable: Physical percent complete (0-100). Manual EVM entry by scheduler (MSP PhysicalPercentComplete). Authoritative for BCWP calculations. Captured separately from percent_complete on MSP imports.
    - `planned_start` string, date, nullable: Planned start date (ISO 8601)
    - `planned_finish` string, date, nullable: Planned finish date (ISO 8601)
    - `actual_start` string, date, nullable: Actual start date (ISO 8601)
    - `actual_finish` string, date, nullable: Actual finish date (ISO 8601)
    - `baseline_start` string, date, nullable: Baseline start date (ISO 8601)
    - `baseline_finish` string, date, nullable: Baseline finish date (ISO 8601)
    - `constraint_type` string, nullable: Constraint type: ASAP, ALAP, SNET, SNLT, FNET, FNLT, MSO, MFO
    - `constraint_date` string, date, nullable: Constraint date if applicable (ISO 8601)
    - `task_type` string, nullable: Task type classification. Valid values: task (default), milestone, loe, summary, schedule_margin, planning_package, slpp, schedule_visibility. Drives DCMA check exclusions per PAM 200.1 § 3.2.
    - `wbs_code` string, nullable: WBS code (e.g., '1.2.3')
    - `organization_code` string, nullable: Org/dept identifier for anomaly categorization (Progress Audit)
    - `custom_field_map` object, nullable: All WBS/OBS-pattern custom fields discovered in this MS Project file, keyed by alias (e.g., 'CWBS', 'OBS'). Null for XER imports or when no matching aliases exist.
    - `forecast_start` string, date, nullable: Current forecast start date (ISO 8601)
    - `forecast_finish` string, date, nullable: Current forecast finish date (ISO 8601)
    - `total_float_days` number, nullable: Pre-computed total float in days. Auto-computed by CPM if absent.
    - `baseline_duration_days` number, nullable: Baseline duration in days. Auto-computed from baseline dates if absent.
    - `delay_category` string, nullable: Delay attribution category. Valid values: owner, contractor, design, procurement, weather, force_majeure.
    - `earned_value` number, nullable: Earned Value (BCWP) in cost units. Requires options.include_ev_validation.
    - `budgeted_cost` number, nullable: Budgeted Cost of Work Scheduled (BCWS) in cost units.
    - `approval_required` boolean, nullable: Whether this task requires explicit approval before it can start.
    - `approval_status` string, nullable: Approval workflow state. Valid values: not_required, pending, approved, rejected.
  - `options` CPMOptions: Options for CPM calculation.
    - `include_network_details` boolean: Include network details (start/finish tasks, relationship types)
    - `relationship_types` string[], nullable: Optional relationship-type filter for network aggregation and details (FS, SS, FF, SF).

## Response `200`

Successful Response

- BellatorResponseCPMData
  - `status` 'pass' | 'fail' | 'warning' | 'info', required: Top-level result status — always present in every response.
  - `score` number, nullable
  - `grade` 'A' | 'B' | 'C' | 'D' | 'F': Letter grade derived from a 0–100 score. Null on non-scoring endpoints.
  - `summary` string, nullable
  - `breakdown` object, nullable
  - `findings` Finding[]
    - `code` string, required: Stable machine-readable identifier e.g. DCMA_CHECK_8_HIGH_DURATION
    - `severity` 'critical' | 'high' | 'medium' | 'low' | 'info', required: Severity level for findings; reused as priority level for recommendations.
    - `title` string, required: Short human-readable label
    - `description` string, required: Full explanation of the issue
    - `standard` string, nullable: Standard citation e.g. 'DCMA PAM 200.1 Check #8'
    - `affected_tasks` string[]: Task IDs implicated by this finding
    - `metric_value` number, nullable: Observed measurement e.g. 60.0 days
    - `threshold` number, nullable: Threshold that was violated e.g. 44.0 days
  - `recommendations` Recommendation[]
    - `priority` 'critical' | 'high' | 'medium' | 'low' | 'info', required: Severity level for findings; reused as priority level for recommendations.
    - `action` string, required: What to do — specific and actionable
    - `standard` string, nullable: Supporting standard citation
    - `finding_codes` string[]: Finding.code values this recommendation addresses
  - `data` CPMData: Data payload for CPM calculation response. Per CPM API Specification v1.0.0: - critical_path: Ordered list of task IDs on the critical path - project_duration: Total project duration in days - critical_path_length: Length of critical path in days (equals project_duration) - task_count: Number of tasks in the schedule - dependency_count: Total number of dependencies - tasks: Per-task timing information - network_details: Optional network structure details - processing_metadata: Processing time and algorithm version
    - `critical_path` string[], required: Task IDs on the critical path
    - `project_duration` number, required: Total project duration in days
    - `critical_path_length` number, required: Critical path length in days
    - `task_count` integer, required: Number of tasks
    - `dependency_count` integer, required: Number of dependencies
    - `relationship_type_distribution` object: Count of dependencies by relationship type (effective view)
    - `relationship_filter_applied` string[], nullable: Relationship-type filter used to aggregate dependency view
    - `tasks` object, required: Task timing information
    - `network_details` NetworkDetails: Network structure details.
      - `start_tasks` string[], required: Tasks with no predecessors
      - `finish_tasks` string[], required: Tasks with no successors
      - `relationship_types` string[], required: Relationship types used (FS, SS, FF, SF)
      - `relationship_type_distribution` object: Count of dependencies by relationship type in the effective network view
      - `relationship_filter_applied` string[], nullable: Relationship-type filter applied to network aggregation (if provided)
      - `dependency_count_filtered` integer, required: Dependency count after applying relationship-type filter
      - `dependency_count_total` integer, required: Total dependency count before applying relationship-type filter
      - `has_negative_float` boolean, required: Whether any tasks have negative float
    - `processing_metadata` AppApiV1ScheduleAnalysisCpmProcessingMetadata, required: Processing metadata.
      - `processing_time_ms` number, required: Processing time in milliseconds
      - `algorithm_version` string, required: CPM algorithm version
  - `simulation` SimulationEnvelope: Probabilistic simulation outputs for Tier 3 endpoints. Null on all Tier 1 and Tier 2 responses. When Tier 3 launches, this field transitions from null to populated without changing any other envelope field — existing consumers are unaffected.
    - `method` string, required: Simulation method: monte_carlo | latin_hypercube
    - `trial_count` integer, required
    - `duration_days` PercentileResult: Percentile distribution across simulation trials. Reserved for Tier 3 Monte Carlo / risk simulation endpoints (v0.3.0+).
      - `p10` number, required: 10th percentile outcome
      - `p50` number, required: 50th percentile (median)
      - `p80` number, required: 80th percentile — common contract delivery threshold
      - `p90` number, required: 90th percentile
      - `mean` number, required
      - `std_dev` number, required
    - `cost` PercentileResult: Percentile distribution across simulation trials. Reserved for Tier 3 Monte Carlo / risk simulation endpoints (v0.3.0+).
      - `p10` number, required: 10th percentile outcome
      - `p50` number, required: 50th percentile (median)
      - `p80` number, required: 80th percentile — common contract delivery threshold
      - `p90` number, required: 90th percentile
      - `mean` number, required
      - `std_dev` number, required
    - `completion_date` object, nullable: Map of p-value strings to ISO completion dates e.g. {'p50': '2027-04-15'}
  - `metadata` ResponseMetadata, required: Audit trail and processing context — always present, never null.
    - `task_count` integer, required: Number of tasks in the submitted schedule
    - `processing_time_ms` integer, nullable: Wall-clock processing time in milliseconds
    - `api_version` string: API version that produced this response
    - `endpoint` string, required: Endpoint path e.g. /api/v1/health/score
    - `standards_applied` string[]: Standards consulted during analysis e.g. ['DCMA PAM 200.1', 'GAO BP-2']
    - `confidence` number, nullable: Confidence in the result (0–1). Present on scoring endpoints.
    - `status_date` string, nullable: ISO date used as analysis reference point. Present on time-aware analyses.

## Other responses

- `422`: Validation Error

---

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