Inspect the shell prefix and session environment

Use Pi 1.0.4 and its built-in Bash tool. You will compare the model’s command with your own ! command. The configuration and manual commands below are an educational adaptation of the existing Chapter 9 tests; the tests remain the canonical executable evidence.

Configure a visible prefix

Merge this fragment into <project>/.pi/settings.json, then run /reload:

{
  "shellCommandPrefix": "export FROM_PREFIX=yes"
}

{
  "shellCommandPrefix": "export FROM_PREFIX=yes"
}

Pi prepends this prefix to both its built-in bash tool and user-entered ! or !! commands. It runs again before every command. On native Windows, use Git Bash; if needed set shellPath to C:\Program Files\Git\bin\bash.exe with escaped backslashes in JSON. Do not set it to an interactive profile.

Ask the model to run the inspection

Copy the entire command below and ask Pi: Run this with the built-in bash tool and show the output unchanged.

echo "prefix=$FROM_PREFIX"
echo "id=[$PI_SESSION_ID] provider=[$PI_PROVIDER] model=[$PI_MODEL]"
echo "level=[$PI_REASONING_LEVEL] file=[$PI_SESSION_FILE]"

echo "prefix=$FROM_PREFIX"
echo "id=[$PI_SESSION_ID] provider=[$PI_PROVIDER] model=[$PI_MODEL]"
echo "level=[$PI_REASONING_LEVEL] file=[$PI_SESSION_FILE]"

Compare your own command

Enter this in Pi’s editor (the leading ! belongs to Pi, not a shell script):

!echo "prefix=$FROM_PREFIX id=[$PI_SESSION_ID]"

!echo "prefix=$FROM_PREFIX id=[$PI_SESSION_ID]"

Expected outcome

Path	Prefix	Session variables
Model invokes built-in `bash`	`prefix=yes`	Pi injects the current session and selected model values
You enter `!` or `!!`	`prefix=yes`	Pi does not inject the five session variables

For a clean parent environment, the user-entered command is expected to print:

prefix=yes id=[]

prefix=yes id=[]

The model-facing output includes a non-empty session ID. Provider, model, reasoning level and persisted session path depend on your session; an ephemeral session has no session-file value. These are expected reader results, not a transcript of your machine. If your parent environment already exports a PI_* variable, a user command may inherit it; non-injection does not promise that inherited variables are absent.

Mechanism and limitations

Documented: pinned shell-aliases.md specifies the prefix and fresh non-interactive shell. environment-variables.md specifies the five variables and the distinction between tool calls and ! / !!. Observed: the canonical ch09-shell/shell.test.ts drives the real Bash tool and executeBash with a scripted provider; its assertions cover the prefix in both paths, model-facing injection, ephemeral sessions and live reasoning-level changes. These tests use Git Bash on Windows in the current verification environment.

An extension that replaces Bash controls its own setup and may bypass this prefix. Selecting PowerShell for the model does not make your ! commands use PowerShell. This example does not demonstrate real-model compliance with your request to run the inspection.

Canonical tests .

Understand this example

Copy this prompt into your AI tool. No code runs here.


Canonical example context
Chapter: Shells, Processes, and Environment Variables
https://aibussin.com/books/pi/09-chapter/
Example: Inspect the shell prefix and session environment
https://aibussin.com/examples/pi/09-chapter/


Use Pi **1.0.4** and its built-in Bash tool. You will compare the model's command
with your own `!` command. The configuration and manual commands below are an
educational adaptation of the existing Chapter 9 tests; the tests remain the
canonical executable evidence.

## Configure a visible prefix

Merge this fragment into `<project>/.pi/settings.json`, then run `/reload`:

```json
{
  "shellCommandPrefix": "export FROM_PREFIX=yes"
}
```

Pi prepends this prefix to both its built-in `bash` tool and user-entered `!` or
`!!` commands. It runs again before every command. On native Windows, use Git
Bash; if needed set `shellPath` to `C:\Program Files\Git\bin\bash.exe`
with escaped backslashes in JSON. Do not set it to an interactive profile.

## Ask the model to run the inspection

Copy the entire command below and ask Pi: **Run this with the built-in bash tool
and show the output unchanged.**

```bash
echo "prefix=$FROM_PREFIX"
echo "id=[$PI_SESSION_ID] provider=[$PI_PROVIDER] model=[$PI_MODEL]"
echo "level=[$PI_REASONING_LEVEL] file=[$PI_SESSION_FILE]"
```

## Compare your own command

Enter this in Pi's editor (the leading `!` belongs to Pi, not a shell script):

```text
!echo "prefix=$FROM_PREFIX id=[$PI_SESSION_ID]"
```

## Expected outcome

| Path | Prefix | Session variables |
|---|---|---|
| Model invokes built-in `bash` | `prefix=yes` | Pi injects the current session and selected model values |
| You enter `!` or `!!` | `prefix=yes` | Pi does not inject the five session variables |

For a clean parent environment, the user-entered command is expected to print:

```text
prefix=yes id=[]
```

The model-facing output includes a non-empty session ID. Provider, model,
reasoning level and persisted session path depend on your session; an ephemeral
session has no session-file value. **These are expected reader results, not a
transcript of your machine.** If your parent environment already exports a
`PI_*` variable, a user command may inherit it; non-injection does not promise
that inherited variables are absent.

## Mechanism and limitations

**Documented:** pinned `shell-aliases.md` specifies the prefix and fresh
non-interactive shell. `environment-variables.md` specifies the five variables
and the distinction between tool calls and `!` / `!!`. **Observed:** the canonical
`ch09-shell/shell.test.ts` drives the real Bash tool and `executeBash` with a
scripted provider; its assertions cover the prefix in both paths, model-facing
injection, ephemeral sessions and live reasoning-level changes. These tests use
Git Bash on Windows in the current verification environment.

An extension that replaces Bash controls its own setup and may bypass this
prefix. Selecting PowerShell for the model does not make your `!` commands use
PowerShell. This example does not demonstrate real-model compliance with your
request to run the inspection.

[Canonical tests](https://github.com/ernanhughes/pi/blob/main/examples/ch09-shell/shell.test.ts).
<!-- pi-source: examples/ch09-shell/shell.test.ts sha256=9a6a90ec3938bcd9ed4fe2c91b7ffdf0efba4c4ba01697713a08f15929251dbd -->
<!-- pi-source: examples/node_modules/@earendil-works/pi-coding-agent/docs/shell-aliases.md sha256=ebb55456870455b4da91cfd054ae2ac9b3a417e6ff48a009587c33e68ecd7807 -->
<!-- pi-source: examples/node_modules/@earendil-works/pi-coding-agent/docs/environment-variables.md sha256=ed17a738cf346e687d391fcad3b55e39063626081f8eebd9563f2f5e0491f542 -->


Explain how this implementation demonstrates the chapter's mechanism, its expected outcome and its limitations.
Distinguish documented behaviour, observed behaviour and proposed choices. External AI may not be able to access these URLs, especially localhost or private previews. Use the source supplied here; ask for missing material rather than inventing it.

Apply this example

Copy this prompt into your AI tool. No code runs here.


Canonical example context
Chapter: Shells, Processes, and Environment Variables
https://aibussin.com/books/pi/09-chapter/
Example: Inspect the shell prefix and session environment
https://aibussin.com/examples/pi/09-chapter/


Use Pi **1.0.4** and its built-in Bash tool. You will compare the model's command
with your own `!` command. The configuration and manual commands below are an
educational adaptation of the existing Chapter 9 tests; the tests remain the
canonical executable evidence.

## Configure a visible prefix

Merge this fragment into `<project>/.pi/settings.json`, then run `/reload`:

```json
{
  "shellCommandPrefix": "export FROM_PREFIX=yes"
}
```

Pi prepends this prefix to both its built-in `bash` tool and user-entered `!` or
`!!` commands. It runs again before every command. On native Windows, use Git
Bash; if needed set `shellPath` to `C:\Program Files\Git\bin\bash.exe`
with escaped backslashes in JSON. Do not set it to an interactive profile.

## Ask the model to run the inspection

Copy the entire command below and ask Pi: **Run this with the built-in bash tool
and show the output unchanged.**

```bash
echo "prefix=$FROM_PREFIX"
echo "id=[$PI_SESSION_ID] provider=[$PI_PROVIDER] model=[$PI_MODEL]"
echo "level=[$PI_REASONING_LEVEL] file=[$PI_SESSION_FILE]"
```

## Compare your own command

Enter this in Pi's editor (the leading `!` belongs to Pi, not a shell script):

```text
!echo "prefix=$FROM_PREFIX id=[$PI_SESSION_ID]"
```

## Expected outcome

| Path | Prefix | Session variables |
|---|---|---|
| Model invokes built-in `bash` | `prefix=yes` | Pi injects the current session and selected model values |
| You enter `!` or `!!` | `prefix=yes` | Pi does not inject the five session variables |

For a clean parent environment, the user-entered command is expected to print:

```text
prefix=yes id=[]
```

The model-facing output includes a non-empty session ID. Provider, model,
reasoning level and persisted session path depend on your session; an ephemeral
session has no session-file value. **These are expected reader results, not a
transcript of your machine.** If your parent environment already exports a
`PI_*` variable, a user command may inherit it; non-injection does not promise
that inherited variables are absent.

## Mechanism and limitations

**Documented:** pinned `shell-aliases.md` specifies the prefix and fresh
non-interactive shell. `environment-variables.md` specifies the five variables
and the distinction between tool calls and `!` / `!!`. **Observed:** the canonical
`ch09-shell/shell.test.ts` drives the real Bash tool and `executeBash` with a
scripted provider; its assertions cover the prefix in both paths, model-facing
injection, ephemeral sessions and live reasoning-level changes. These tests use
Git Bash on Windows in the current verification environment.

An extension that replaces Bash controls its own setup and may bypass this
prefix. Selecting PowerShell for the model does not make your `!` commands use
PowerShell. This example does not demonstrate real-model compliance with your
request to run the inspection.

[Canonical tests](https://github.com/ernanhughes/pi/blob/main/examples/ch09-shell/shell.test.ts).
<!-- pi-source: examples/ch09-shell/shell.test.ts sha256=9a6a90ec3938bcd9ed4fe2c91b7ffdf0efba4c4ba01697713a08f15929251dbd -->
<!-- pi-source: examples/node_modules/@earendil-works/pi-coding-agent/docs/shell-aliases.md sha256=ebb55456870455b4da91cfd054ae2ac9b3a417e6ff48a009587c33e68ecd7807 -->
<!-- pi-source: examples/node_modules/@earendil-works/pi-coding-agent/docs/environment-variables.md sha256=ed17a738cf346e687d391fcad3b55e39063626081f8eebd9563f2f5e0491f542 -->


Help me adapt this example to my project. First identify the mechanism. Ask only for project details necessary to assess applicability. Prefer the smallest useful implementation. Explain adaptations before making changes and define verification. The original example does not prove an adaptation works.
Distinguish documented behaviour, observed behaviour and proposed choices. External AI may not be able to access these URLs, especially localhost or private previews. Use the source supplied here; ask for missing material rather than inventing it.