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>
An agent event set its label to the SSH profile's name, so the transcript read
"homeserver · ls -la" -- naming the machine rather than the thing that was done.
Built-in tools set no label at all and fell back to the function name, so a
saved memory read "memory_add". The status line said "Running shell_run…" and
the approval card had its own hand-written wording. Four places, four answers,
nothing checking that any of them agreed.
services/tool_labels.py is the one table all of them read now. Bash, Read,
Write, List, Web search, Memory saved; an icon each, instead of everything
being the sparkle.
The precedence is inverted on purpose. Tool events are persisted in
Message.tool_calls_json, so every agent row already on disk carries the profile
name -- a resolver that preferred the stored value would fix nothing for any
transcript that already exists. So a name the table knows resolves from the
table, and a name it does not -- a custom HTTP tool, an MCP tool, whose labels
are per row and cannot be tabulated -- keeps its own. One rule, both cases
correct. The machine moves to `detail`, where "where this ran" belongs.
tool_label and tool_icon are Jinja globals because a message bubble is rendered
from four handlers, and a fifth thing each of them must remember to pass is a
fifth thing one of them will forget.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
A row in custom_tools becomes a ToolDef like any built-in, offered beside
the thirteen. The registry had to stop being an import-time constant for
that: `resolve_tools` now returns the schemas *and* the runners together,
carried to the loop on the ToolContext.
That closes a hole on the way. `run_tool` looked names up in the global
REGISTRY with no reference to what had been offered, so a model naming a
tool its chat was gated out of -- a family switched off, a permission the
reader lacks -- had it run anyway. The resolved set is now authoritative.
Arguments come from a model, so an argument may fill a hole but never move
the target: the scheme and host of a URL template are literal, values are
escaped for where they land, and the origin is pinned afterwards. Every
redirect hop is checked the way services/fetch.py checks one, and the
secret is dropped if a hop leaves the origin it was issued for.
Also fixes the tool-activity block claiming every library tool had
"searched the web", which it has done since the second family landed.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Jaroslav Beneš