write-patch

Call the obsidian-router patch_file MCP tool with arguments parsed from $ARGUMENTS.

Arguments

Required:

• path — file path relative to vault root.
• operation — append, prepend, or replace.
• targetType — heading, block, or frontmatter.
• target — the target identifier:
  • heading → the FULL heading path joined by :: (e.g. Section 1::Subsection). Just the heading name alone won't work; the parent path is required.
  • block → the block id without the leading ^ (e.g. atp-config).
  • frontmatter → the property name (e.g. status).
• content — new content. String for heading/block; for frontmatter accepts string/number/boolean/array/object (types preserved).

Optional:

• vault — omit for default.
• targetDelimiter — override the heading delimiter (default ::).
• createTargetIfMissing — create the target if absent (heading/frontmatter only).
• applyIfContentPreexists — skip if target already contains the content (idempotency).
• trimTargetWhitespace — trim whitespace around the target before applying.
• ifMatch — a contentSha256 from a prior get_file. Whole-file precondition: the patch is refused with a 409 conflict if the file changed since you read it. (The precondition is checked before patching; the patch itself is not hash-locked — this catches patching stale content, it does not make the patch atomic.)

Argument parsing from $ARGUMENTS

This tool has many parameters. If $ARGUMENTS doesn't make the intent crystal-clear, ask the user before calling. A typical bare invocation as $ARGUMENTS should be path=... operation=... targetType=... target=... content=....

Common quick patterns

• Set a frontmatter key: path=X operation=replace targetType=frontmatter target=<key> content=<value> (consider using write-frontmatter-set instead — friendlier wrapper).
• Append under a heading: path=X operation=append targetType=heading target="Section::Sub" content="...".
• Replace a block: path=X operation=replace targetType=block target=<block-id> content="...".

On failure — remediate, NEVER fall back to filesystem writes

If the call fails, do NOT silently redo it with direct-filesystem tools (Read/Edit/Write on the vault's real path):

• Connection error (ECONNREFUSED, timeout) → vault closed; list_vaults, then ask the user to open it via the openUri link and wait.
• Validation / API error (HTTP 4xx, e.g. invalid-target = heading not the FULL ::-joined path) → fix the arguments, or use a coarser router tool (write_file, append_to_file).

Rationale + message template: the default-vault-health-check convention (canonical source).

Output

After the patch, report what was patched (target type, target, operation).