set fig.cap to options$label - r

Question

How can I programmatically set a figure caption in a knitr hook?
I'd like to set the figure caption, if not explicitly defined, to the chunk label. I've read the knitr docs on options, options, and hooks, and though I think I understand the mechanisms at play, I can't get it to work.
My use-case that perhaps justifies this behavior: my work-flow recently adapted to start my data and visualization exploration in Rmd files. I'll use chunks for cleaning, subsetting, etc, and then a sample chunk for each visualization. This is quick and dirty, meaning minimal markdown. When I look over the report (typically rendered into PDF), I'll look at a figure and want to go straight to the source for it. Though text before/after the figure can provide insight, due to LaTeX figure rules it is not a sure thing. Counting figure numbers is feasible, but not "easy" (and becomes problematic with many figures). Captions are always with the figure, so it'd be great if I can default to filling the caption with the chunk label. (Yes, it's a little lazy of me.)
The MWE is below.
The hook code ran just fine; the returned strings in the hook appeared correctly. However, the figure caption did not change. Exception: when there is a chunk with an undefined fig.cap, all subsequent chunks have their caption set to the first un-captioned chunk name; this doesn't surprise me due to the global nature of opts_chunk, so that's out.
I suspect it might be related to "output hooks" vice "chunk hooks," but this really is a per-chunk thing and I do not want to modify the plot, just set the caption.
MWE:
---
title: "Document Title"
author: "My Name"
output:
pdf_document:
fig_caption: yes
---
# Header
```{r setup}
knit_hooks$set(autocap = function(before, options, envir) {
if (before) {
if (is.null(options$fig.cap)) {
options$fig.cap <- options$label
knitr::opts_current$set(fig.cap = options$label)
knitr::opts_chunk$set(fig.cap = options$label) # wrong!
paste('Set: `', options$label, '`, `',
knitr::opts_current$get('fig.cap'), '`', sep = '')
} else {
paste('Kept: `', options$fig.cap, '`', sep = '')
}
}
})
opts_chunk$set(autocap = TRUE)
```
## No Plot
```{r textOnly}
1+1
```
## Caption Already Set
```{r someplot, fig.cap='someplot caption'}
plot(0)
```
## Caption Not Set
```{r anotherPlot}
plot(1)
```

Answer 1

Is it ok like this ? I simply modify the knitr internal function .img.cap function which can be found here.
```{r}
.img.cap = function(options) {
if(is.null(options$fig.cap)) options$label else options$fig.cap
}
assignInNamespace(".img.cap", .img.cap, ns="knitr")
```

Answer 2

Does it help ?
```{r}
library(knitr)
knit_hooks$set(htmlcap = function(before, options, envir) {
if(!before) {
caption <- ifelse(is.character(options$htmlcap), options$htmlcap, options$label)
paste('<p class="caption">', caption, "</p>", sep="")
}
})
```
```{r Hello, htmlcap=TRUE}
library(ggplot2)
ggplot(diamonds,aes(price,carat)) + geom_point()
```
```{r, htmlcap="Hello again"}
ggplot(diamonds,aes(price,carat)) + geom_point()
```