diffusion uri edit prints a Python traceback for a server-side validation error

Start in phabfive/cli/diffusion.py at the uri edit apply call on line 684, then compare it with the uri create handling around lines 573-577 and inspect the other apply sites in the file. Reproduce the command with --io=read and verify rejected edits print the error on stderr, exit 1, and do not show a traceback.

Found while writing docs/diffusion-uri.md (#377, PR #392).

uri edit is the one apply path in phabfive/cli/diffusion.py that does not
catch PhabfiveDataException, so any error Conduit returns reaches the user as
an unhandled traceback.

Environment

• Python version: 3.14.7
• Phabfive version: 0.10.0 (main at c4b8e93)
• Phorge: the local k3d instance from docs/phorge-setup.md

Steps to Reproduce

Phorge validates I/O per URI: an external URI carries a remote, so it accepts
default, none, observe and mirror — not read. Ask for read on one:

phabfive diffusion uri edit uridoc377 git@github.com:dynamist/phabfive.git --io=read --yes

Any rejected edit does this; the I/O mismatch is just the easiest to trigger.
--dry-run is unaffected, since it never reaches the apply.

Expected Behavior

The same shape every other failure in this file produces:

ERROR: ERR-CONDUIT-CORE: Validation errors:
  - Value "read" is not a valid IO setting for this URI. Available types for this URI are: default, none, observe, mirror.

on stderr, exit 1.

Observed Behavior

Two chained tracebacks, ~35 lines, with the useful sentence on the last one:

Traceback (most recent call last):
  File ".../phabfive/diffusion/core.py", line 890, in apply_uri_edit
    self.phab.diffusion.uri.edit(
...
phabricator.APIError: ERR-CONDUIT-CORE: Validation errors:
  - Value "read" is not a valid IO setting for this URI. Available types for this URI are: default, none, observe, mirror.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
...
  File ".../phabfive/cli/diffusion.py", line 684, in edit
    diffusion.apply_uri_edit(object_id, transactions)
...
phabfive.exceptions.PhabfiveDataException: ERR-CONDUIT-CORE: Validation errors:
  - Value "read" is not a valid IO setting for this URI. Available types for this URI are: default, none, observe, mirror.

Cause

phabfive/cli/diffusion.py:684:

diffusion.apply_uri_edit(object_id, transactions)

bare, where uri create a few lines up (:573-577) has:

try:
    diffusion.apply_uri_create(plan)
except PhabfiveDataException as e:
    typer.echo(f"ERROR: {e}", err=True)
    raise typer.Exit(1)

core.apply_uri_edit already converts APIError to PhabfiveDataException,
so the exception arrives in the right type — nothing catches it.

Worth checking the other apply sites in the file at the same time rather than
patching this one line in isolation.

🤖 Generated with Claude Code