file_write replaces a file entirely, so a model wanting to change one line
either rewrote the whole thing from memory -- silently dropping everything it
did not happen to recall -- or shelled out to sed. file_edit takes a unified
diff instead, and services/agent/patch.py applies it.
Four behaviours carry that module, and each exists because of how models
actually write patches rather than how the format is specified.
Fuzzy offset, exact content. A hunk header is a hint: models count from a
truncated read or from the file as it was three edits ago and get the numbers
wrong, and get the context lines right. So the hinted position is tried, then
the file is scanned outward for an exact match of the context block. One match
wins; more than one refuses, because guessing between two identical blocks is
the one failure that silently corrupts a file.
Line endings are normalised in and restored out, or every hunk on a CRLF file
fails on context that looks identical in the error message. A blank context
line that lost its leading space is read as blank, because trailing whitespace
is stripped by half the things a model's output passes through. And nothing is
written unless every hunk applies: a half-applied file is worse than a refused
one, and the model cannot tell the difference without reading it again.
It refuses a file this reply has not read, in those words. A patch written from
memory either fails on context -- the good case -- or matches something it did
not mean. AgentContext.read_paths records what was read; it lives there because
runners never see a Generation and a read path is a fact about the machine, and
it is shared with the approved copy because as_approved is dataclasses.replace,
which copies field references. It resets each reply, and that is right rather
than a limitation: tool_calls_json is never replayed, so on the next turn the
model does not have the contents either.
Writes and edits both render a git-style diff in the transcript now, escaped
like everything else there and bounded at write time -- a generated file's diff
can be larger than the file, and it sits on the row forever. That costs
file_write one extra SFTP round trip to read the old contents, on the hottest
agent operation, and it is a conscious trade: it is the difference between
seeing what an agent did and having to go and look. It earns its keep twice,
because that read also counts as having read the file.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
The approval card in Auto mode and the missing /effort were one bug. Both
selects hung their hx-patch on an empty sibling form reached by form="…",
and htmx binds a trigger to the annotated element: change fires on the
select and bubbles to its ancestors, which a sibling is not. The live rows
read agent_mode=manual and params_json={} while the browser showed Auto and
Effort: high. policy.py was never involved.
The verb moves onto the control; the empty form stays as value scoping,
which is the half of the CLAUDE.md note that was right. conftest gains
control_named so a test asserts the element carrying the name carries the
verb, rather than asserting the markup that was there throughout.
The composer's highlight was a third instance of the same carelessness in
CSS: .tok-mention is written for the transcript and scoped to nothing, so
the mirror painted its token in accent-coloured monospace over the
textarea's own text. Scoped under .msg; the mirror restates transparency
and font rather than inheriting them, and bleeds by box-shadow.
/effort is now offered before the first prompt and _new_chat reads it.
/index re-walks the project directory on demand, file_write drops the
listing it just invalidated, and the index ladder falls through to SFTP on
a host that refuses exec instead of returning nothing.
A second message during a reply is queued rather than starting a second
concurrent generation: a real Message row with queued set, so it survives a
restart and can be withdrawn. _drain hands one on at the end of a reply,
_inject takes one in at a tool-round boundary so an agent can be steered
mid-task. Stop leaves the queue undelivered. The terminal's Auto toggle
becomes off/copy/send, and send posts straight to the chat without touching
the composer.
@ now offers notes, skills, this chat's attachments and a URL to fetch; a
knowledge base attaches as a reference rather than a copy. copy_document
carries provenance, which was the one attach path that dropped it.
Also fixes an unrelated live bug: the round loop compared against the
global MAX_ROUNDS of 3 while sizing itself from the agent budget of 40, so
agent replies stopped after three rounds and reported forty.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
`plan_submit` records an ordered set of steps and ends the turn. Offered in
Plan mode and nowhere else: it stops the reply, and a model in Auto mode
proposing a plan instead of doing the work would be obeying the wrong
instinct at the worst moment.
The plan is stored on the message rather than parsed back out of the prose,
so the button sends exactly what was proposed. It gets one more request to
say what it proposed and why -- a bubble containing only a card reads as
though the model had nothing to add -- but with the tools withdrawn, so
"one more round" cannot become three rounds of it changing its mind about a
plan somebody is being asked to approve.
Carrying it out switches to Edit, never Auto. The plan was written under a
mode where every command stopped for approval, and a button that also
removed the asking is not the button anybody pressed. It goes back quoted
and attributed, not stated: a plan whose text came out of a file the model
read must not arrive in the most trusted role in the transcript wearing the
reader's authority.
Also closes the rewind gap. Editing or regenerating a turn rewinds the
transcript and not the machine, so `rewound_at` is stamped and the harness
says so. Nothing tries to undo anything out there -- the project directory
is somebody's real working tree, and deleting their work to match a rewound
transcript would be far worse than the inconsistency.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
The four tools an agent chat has -- shell_run, file_read, file_write,
file_list -- and the mode table wired into the loop that decides which of
them stop for approval. Verified end to end against a real Kali container
over SSH: the card shows the command, allowing it runs it there, and the
file it writes is visible from outside.
The mode is enforced in `_authorise`, in the generation loop, server-side,
keyed on each tool's declared risk. Not in the prompt: a model is told
which mode it is in so it behaves sensibly, but everything it reads -- a
web page, a README, the output of the last command -- is untrusted, and a
rule written only into a system message is one a poisoned file can argue
with. Within an agent chat every call goes through the table, including
the built-in ones, because notes_edit writes and Plan mode meaning "look
but do not touch" has to mean that too.
Two things this turned up.
The runners re-check the mode as a backstop, and that backstop refused the
very thing a person had just approved -- the mode says "ask", and asking
was exactly what happened. Approval is now threaded per call, on a copy of
the context, because a round runs its calls together and only some of them
were allowed.
And the harness said nothing at all, because `registry` maps an offered
tool *name* back to a family and did not know the agent tools existed. So
shell_run resolved to no family and the fragment naming the machine, the
directory and the mode was never admitted. The same omission cost custom
tools their guidance once already; there is a test for it now.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Jaroslav Beneš