> ## Documentation Index
> Fetch the complete documentation index at: https://docs.glidepathcpm.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Automatic Scheduling

> When and how GlidePath recalculates the CPM schedule

# Automatic Scheduling

GlidePath recalculates the entire schedule automatically every time you make a change that affects task timing. You do not need to click a "Calculate" button -- the engine runs in the background and updates dates, float values, and critical path highlighting instantly.

## Feature Spec Reference

**Module 3.4 -- Float Display and Color Coding**\
**Module 3.6 -- CPM Recalculation Triggers**

## What Triggers a Recalculation

GlidePath recalculates CPM after any of these changes:

| Change Type                                     | Recalculation Triggered |
| ----------------------------------------------- | ----------------------- |
| Task duration edited                            | Yes                     |
| Task start or finish date directly edited       | Yes                     |
| Dependency added or removed                     | Yes                     |
| Dependency type or lag changed                  | Yes                     |
| Constraint added, changed, or removed           | Yes                     |
| Task indented or outdented (WBS change)         | Yes                     |
| Task added or deleted                           | Yes                     |
| Calendar or work week changed                   | Yes                     |
| Holiday added or removed                        | Yes                     |
| Resource assignment changed (affects calendars) | Yes                     |

## What Gets Updated

After each recalculation, GlidePath updates:

* **Task bar positions** in the Gantt timeline
* **Start and Finish date columns** in the task list
* **Float/slack values** in the Float column (if visible)
* **Critical path highlighting** (red bars for zero-float tasks)
* **Dependency line colors** (red lines for critical-path links)
* **Summary task dates** (rolled up from child tasks)
* **Dashboard metrics** (SPI, CPI, schedule health indicators)

## Directly Scheduled Tasks

By default, tasks are scheduled **As-Soon-As-Possible (ASAP)**, meaning the CPM engine places them at the earliest valid date given their predecessors and constraints.

If you directly edit a task's start date (by typing in the Start column), GlidePath applies an implicit **Start No Earlier Than** constraint at that date. This pins the task to your chosen date while still allowing CPM to push it later if a predecessor causes it to start after that date.

To release a pinned task back to pure CPM scheduling:

1. Open the Task Detail Panel (double-click the task)
2. Set **Constraint Type** to **As Soon As Possible**
3. Clear the constraint date if one was set

## Float Display

Float is shown in the task list when the **Float** column is enabled. To enable it:

1. Click **Columns** in the Gantt toolbar
2. Check **Float**

Float values update instantly with every recalculation:

| Float Color  | Range    | Meaning                          |
| ------------ | -------- | -------------------------------- |
| Red (bold)   | 0 days   | Critical -- on the critical path |
| Yellow/amber | 1-3 days | Near-critical -- watch closely   |
| Green        | 4+ days  | Has scheduling flexibility       |

## Summary Task Scheduling

Summary (parent) tasks do not have their own CPM-calculated dates. Their start and finish are always derived from their children:

* **Summary Start** = earliest start date among all child tasks
* **Summary Finish** = latest finish date among all child tasks

When a child task moves, the summary task updates to match. You cannot directly edit a summary task's start or finish date -- instead, edit the child tasks.

## Performance on Large Schedules

GlidePath is optimized to recalculate CPM in under one second for schedules with up to 500 tasks. For very large schedules (500+ tasks), recalculation may take 1-3 seconds. During recalculation, a brief loading indicator appears in the toolbar.

See [Performance Tips](/reference/02-performance-tips) for guidance on keeping large schedules responsive.

***

## Next Steps

* [Constraints Deep Dive](/scheduling/04-constraints-deep-dive)
* [CPM Fundamentals](/scheduling/01-cpm-fundamentals)
* [Critical Path](/dependencies/04-critical-path)